JP2002237680A - Printed circuit board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed circuit board capable of forming a blind hole having sure conductivity, without causing damages to an inner layer conductor circuit due to laser beam, and to provide a method or manufacturing the same. SOLUTION: The printed circuit board comprises two or more insulating layers 511 to 515 on an inner layer conductor circuit 562, and a via hole 503 metal plated and arriving at the conductor circuit 562 via the two or more layers 511 to 515 from the uppermost surface of the insulating layers. The circuit board further comprises a reinforcing annular dummy land 504, having an opening hole including the same diameter as that of the via hole at a boundary part, in which the two or more layers 511 to 515 mutually face each other and are joined to a via hole inner wall metal plating film 521.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board in which a via hole is formed using a laser beam, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG. 61, for example, as shown in FIG. 61, a printed wiring board has a plurality of insulating layers 91 to 93 stacked therein, inner layer conductor circuits 95 and 97 provided between the respective layers, and outermost outer conductor circuits 94. Are electrically connected by a metal plating film 96 provided in the via holes 99a and 99b. As the insulating layers 91 to 93, a resin substrate such as a glass-epoxy substrate is used. Via hole 99a,
99b is a blind via hole one of which is covered and the other is opened.

[0003] Methods for drilling the via holes include a method using a drill and a method using a laser beam. However, the above-described drilling method causes unevenness in depth accuracy. In recent years, the density of wiring patterns has been increased, and the diameter of via holes has been required to be smaller and smaller.

[0004] Therefore, drilling with a laser beam has been proposed (Japanese Patent Laid-Open No. 62-216297, Japanese Patent Laid-Open No.
No. 65594).

According to this method, as shown in FIG.
Utilizing the property that the laser beam 81 reflects on the inner conductor circuits 95 and 97 made of metal such as a copper foil and a metal plating film, the via holes 99a and 99b are formed from the outermost surface to the inner conductor circuit inside the multilayer board. Can be drilled.

[0006]

However, as shown in FIG. 62, in a printed wiring board, a via hole 99a whose via hole reaches an inner layer conductor circuit 95 near the outermost surface of the printed wiring board, and an inner layer conductor farther from the outermost surface. A relatively deep via hole 99b reaching the circuit 97 is mixed.

For this reason, when the drilling process is performed by the laser beam 81, as shown in FIG.
9b is not damaged, but the inner conductor circuit 95 at the bottom of the shallow via hole 99b is not damaged.
May be torn at its center and cause damage 98 such as swelling.

When such damage occurs, the inner layer conductor circuit 9
5, When a metal plating film is formed between each surface of the via hole 99a and the external conductor circuit, a broken piece 98a of the inner conductor circuit generated by the damage 98 remains in the via hole 99a, so that the metal plating film cannot be formed sufficiently. Sometimes. Such an insufficient metal plating film causes the inner conductor circuit 95
Adversely affects the electrical continuity between the printed circuit board and the external conductor circuit 94, and sometimes the printed wiring board itself is rejected.

As described above, the reason why the inner conductor circuit 95 is damaged is as shown in FIG. 62, in the case of the shallow via hole 99a and the case of the deep via hole 99b.
This is for irradiating the laser beam 81 with an intensity necessary for drilling the deep via hole 99b.

Therefore, it is conceivable to irradiate a laser beam having an intensity corresponding to the processing depth of each via hole. However, the number of via holes provided in one printed wiring board is large, for example, 500 to 10000, and adjusting the intensity of laser light for each via hole is complicated and requires an expensive control device. I do.

Further, a blackening film is provided on the surfaces of the inner conductor circuits 95 and 97 in order to secure adhesion to the insulating layers 91 and 92. Since the blackening film has a high energy absorption of laser light, the inner conductor circuit provided with the blackening film on its surface may melt and expand, causing breakage or damage.

Further, since the insulating layer made of resin or the like is exposed in the via hole, it is difficult to form a metal plating film. Therefore, the bonding property between the inner wall of the via hole and the metal plating film is low, and the metal plating film may be peeled off or fall off, which may adversely affect the electrical conduction of the via hole.

Further, the formation of a metal plating film in a via hole is carried out while flowing an electroplating solution inside and outside the via hole. However, as the inner diameter of the hole becomes smaller, the flow of the electroplating solution becomes more difficult and the plating film is formed. The via holes may become non-uniform and the electrical conduction of the via holes may be insufficient.

In addition, instead of the metal plating film, the via hole is filled with solder to provide conduction, but in this case, the bonding strength between the inner wall of the via hole and the solder is low, and the external pressure is reduced. May cause the solder to come off.

Further, it is required to use a hole formed by laser beam irradiation in addition to the above-described formation of a via hole.

In view of the above problems, the present invention can form a via hole having reliable conductivity without causing damage to an inner conductor circuit by laser light, and can realize a new circuit formation by laser light. An object of the present invention is to provide a printed wiring board and a method for manufacturing the same.

[0017]

The present invention has two or more insulating layers on an inner conductor circuit, and penetrates the two or more insulating layers from the outermost surface of the insulating layer to reach the inner conductor circuit. A printed wiring board having a via hole, and an internal metal plating film for electrically connecting the inner layer conductor circuit and the outer layer conductor circuit formed on the outermost surface in the via hole; A reinforcing annular dummy land having an opening around the via hole is provided at a boundary portion where the insulating layers face each other, and the annular dummy land is joined to the internal metal plating film. Printed wiring board.

In the printed wiring board, an inner layer conductor circuit may be provided at the boundary portion. The annular dummy land is provided separately so as not to conduct with the inner layer conductor circuit. It is. The annular dummy land is preferably made of a metal such as copper or nickel.

The operation of the present invention will be described. In the printed wiring board according to the present invention, an annular dummy land for reinforcement is provided around the via hole, and the annular dummy land is joined to the internal metal plating film in the via hole. The inner metal plating film is hardly bonded to the exposed portion of the insulating layer in the via hole, but can be strongly bonded to the side surface of the annular dummy land. Therefore, the internal metal plating film can be strongly bonded in the via hole. Therefore, peeling and falling off of the internal metal plating film can be prevented.

In some cases, an inner layer conductor circuit is provided at the boundary portion. If a via hole is formed in a portion where the inner layer conductor circuit does not exist, the peripheral edge of the opening of the via hole becomes an inner layer conductor circuit at the boundary portion. Is thinner by the thickness of the inner-layer conductor circuit than at the location where. For this reason, a dent corresponding to the thickness of the inner-layer conductor circuit is formed around the opening of the via hole. This is particularly likely to occur in via holes provided through four or more insulating layers (FIG. 3).
3). By providing the above annular dummy land,
The dent at the periphery of the via hole opening can be prevented.

As described above, according to the present invention, it is possible to provide a printed wiring board in which the internal metal plating film is strongly bonded to the inside of the via hole.

Further, the printed wiring board obtained in the present invention can be used for, for example, a memory module, a multi-chip module, a mother board, a daughter board, a plastic package, etc., which require high connection reliability.

It is preferable that the annular dummy land has an outer diameter larger than the diameter of the via hole and has an opening having the same diameter as the diameter of the via hole. Thereby, the annular dummy land can be arranged more stably and the reinforcing effect can be further enhanced.

As a method of manufacturing the printed wiring board, two or more insulating layers are provided on the inner conductor circuit, and the inner layer is formed by penetrating the two or more insulating layers from the outermost surface of the insulating layer. A via hole reaching the conductor circuit, and an internal metal plating film for electrically connecting the inner layer conductor circuit and the outer layer conductor circuit formed on the outermost surface is provided in the via hole; A reinforcing annular dummy land having an opening around the via hole is provided at a boundary portion where two or more insulating layers face each other, and the annular dummy land is connected to the internal metal plating film by a printed dummy land. In the method for manufacturing a wiring board, the via hole is formed by irradiating a laser beam from the outermost surface toward the inner-layer conductor circuit. Through the opening hole of Mirando allowed to reach the inner layer conductor circuit, there is a method for manufacturing a printed wiring board, which comprises subsequently forming the inner metal plated film.

According to this manufacturing method, similarly to the above-described printed wiring board, a printed wiring board in which the inside of the via hole and the internal metal plating film are strongly bonded can be obtained. Also,
Since the via hole is formed by laser light irradiation, a very small via hole having a diameter of 300 μm or less can be easily obtained.

As described above, according to this manufacturing method, it is possible to easily manufacture a printed wiring board having an inner metal plating film strongly bonded to the inside of a via hole and having a small diameter via hole.

The formation of a via hole by laser light is performed by irradiating a laser light to a portion where a via hole is to be formed. As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no thermal effect. The formation of the via hole by the laser beam irradiation is such that the insulating layer is vaporized and removed by the high energy, and a hole is sequentially formed in the printed wiring board. When the tip of the laser beam reaches the inner conductor circuit, the laser beam is reflected by the metal inner conductor circuit. Therefore, the laser beam irradiation is stopped here.

It is preferable that the annular dummy land has an outer diameter larger than the diameter of the via hole and has an opening having the same diameter as the diameter of the via hole. Thus, similarly to the above, the annular dummy lands can be arranged more stably and the reinforcing effect can be further enhanced.

Next, at least two insulating layers made of synthetic resin, an inner conductor circuit provided between the insulating layers, and a blind via hole provided from the outermost surface of the insulating layer toward the inner conductor circuit. In manufacturing a printed wiring board having the following, an opening hole is previously provided in the center portion of the inner conductor circuit located at the bottom of the blind via hole, and then laser light is irradiated from the outermost surface of the insulating layer. Then, it is preferable to perform a manufacturing method in which the blind via hole is formed, and then a metal plating film is formed on the surface of the inner layer conductor circuit and the blind via hole.

In the preferred manufacturing method, the most remarkable point is that the inner conductor circuit is provided with an opening in the center thereof in advance.

Next, the operation and effect of the preferred manufacturing method will be described. In the above preferred manufacturing method, a laser beam is irradiated to a portion where a blind via hole is to be formed, thereby forming a blind via hole extending from the outermost surface of the printed wiring board to the inner conductor circuit. At this time, the laser light vaporizes and removes the insulating layer of the printed wiring board by its high energy, and sequentially drills holes inward of the printed wiring board. When the tip of the laser beam reaches the inner conductor circuit, the laser beam is reflected by the metal inner conductor circuit. for that reason,
Here, the irradiation of the laser beam is stopped. This completes the blind via hole drilling process.

What is important here is that, in forming a large number of blind via holes, for example, a laser beam is applied to each of the holes one by one in a spot-like manner to perform the drilling process. On the other hand, the irradiation time or energy required for drilling differs between a shallow blind via hole and a deep blind via hole. However, since irradiation is performed sequentially and continuously as described above, the time and energy are set for each hole to ensure that a deep blind via hole is formed. Process.

In the preferred manufacturing method, the opening is formed in the inner conductor circuit of the shallow blind via hole. Therefore, when a shallow blind via hole is drilled, even if the laser beam has already reached the inner layer conductor circuit and the drilling has been completed, the laser beam will continue to be irradiated under the conditions for drilling the deep blind via hole. . However, at this time, a portion of the laser beam at the central portion where the energy is large is irradiated to the opening, and passes through the opening.

Then, the laser beam passing through the opening hole is
Irradiation is performed only on the insulating layer at the end of the opening hole. Therefore, in the inner layer conductor circuit portion, the insulating layer ahead of the opening hole is slightly opened, but the inner layer conductor circuit itself is not damaged. When the deep blind via hole is opened, the laser beam is not reflected when the inner layer conductor circuit reflects the laser beam, so that no damage occurs.

There is also a method of irradiating the laser beam simultaneously to all the hole processing regardless of whether the hole is a shallow blind via hole or a deep blind via hole. At this time, the same operation and effect as described above can be obtained (see Reference Example 1).

For each of the blind via holes having different depths formed as described above, the metal plating film is formed therein as in the conventional case. At this time, since none of the inner layer conductor circuits is damaged by the laser beam as described above, the state of insufficient metal plating film formation as shown in the above-described conventional example can be avoided, and the conductivity is excellent. Metal plating film can be formed.

Examples of the insulating layer of the synthetic resin include a synthetic resin alone, a resin base made of a synthetic resin and an inorganic filler, and a cloth base made of a synthetic resin and an inorganic cloth. The above synthetic resins include epoxy resin, phenol resin,
Examples include polyimide resin, polybutadiene resin, and fluorinated resin. Insulation layers made of only these synthetic resins are shown in Reference Example 1.
As shown in (1), a prepreg adhesive layer may be laminated between other insulating layers.

Inorganic fillers to be added to the synthetic resin include short glass fibers, silica powder, mica powder, and the like.
There are alumina, carbon, and the like. A substrate made of a mixture of a synthetic resin and an inorganic filler has a higher strength than a synthetic resin alone.

The above-mentioned cloth base material refers to a substrate made of a cloth woven or knitted in a cloth shape and a synthetic resin, such as a glass-epoxy substrate and a glass-polyimide substrate. As such a cloth base material, there is a base material in which the cloth is impregnated with a synthetic resin. Examples of the material of the cloth include glass fiber cloth, carbon cloth, and aramid cloth. As the synthetic resin, the same material as described above is used.

Drilling by laser light is performed by irradiating laser light to a portion where a blind via hole is to be formed. As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no thermal effect.

The blind via hole is formed up to a desired inner conductor circuit provided inside the printed wiring board. In the blind via hole thus formed, a continuous metal plating film is formed from the inner conductor circuit at the bottom and the wall surface of the blind via hole to the outer conductor circuit.

Next, when the printed wiring board has two or more inner layer conductor circuits and the blind via holes are provided in each inner layer conductor circuit, the outermost surface on the side irradiated with the laser beam is provided. It is preferable that the opening is provided in the inner conductor circuit on the near side, while the inner conductor circuit on the far side from the outermost surface is irradiated with laser light without providing the opening. Thereby, the same operation and effect as described above can be obtained.

The opening hole provided in the inner conductor circuit is preferably 30 to 60% of the diameter of the blind via hole. When the opening hole diameter is less than 30%, when the distance between the inner layer conductor circuit provided with the opening hole and the innermost conductor circuit at the deepest portion where the opening hole is not provided is large, the inner layer conductor circuit provided with the opening hole has May be damaged.
On the other hand, if it exceeds 60%, the connection between the copper plating and the inner conductor circuit may not be sufficient.

Preferably, the metal plating film is formed so as to cover an opening of the inner conductor circuit. As a result, the bottom of the blind via hole is completely covered with the metal plating film, so that moisture does not enter the blind via hole.

The printed wiring board can be used for a printed wiring board requiring high connection reliability, for example, a memory module, a multi-chip module, a mother board, a daughter board, a plastic package, and the like.

Next, at least two insulating layers made of synthetic resin, an inner conductor circuit provided between the insulating layers, and a plurality of insulating layers arranged from the outermost surface toward the inner conductor circuit and having different depths. In manufacturing a printed wiring board having a blind via hole, the blind via hole is formed by sequentially irradiating a laser beam to each blind via hole. Using a reference laser beam having the energy intensity necessary to perform the above-mentioned steps, irradiating the above-mentioned reference laser beam when piercing the above-mentioned reference hole, and irradiating the above-mentioned reference laser beam several times when piercing a blind via hole deeper than that. It is preferable to perform a manufacturing method of drilling.

The most remarkable point in the preferred manufacturing method is that the reference laser beam is used, and the reference hole is irradiated with the reference laser beam, while the blind via hole deeper than the reference hole is used. Irradiating light multiple times.

Next, the operation and effect of the preferred manufacturing method will be described. In the above preferred manufacturing method, a laser beam is irradiated to a portion where a blind via hole is to be formed, thereby forming a blind via hole extending from the outermost surface of the printed wiring board to the inner conductor circuit. At this time, the laser light vaporizes and removes the insulating layer of the printed wiring board by its high energy, and sequentially drills holes inward of the printed wiring board. When the tip of the laser beam reaches the inner conductor circuit, the laser beam is reflected by the metal inner conductor circuit. for that reason,
Here, the irradiation of the laser beam is stopped. This completes the blind via hole drilling process.

When drilling a large number of blind via holes, the holes are drilled by sequentially irradiating a laser beam to each of the holes. At this time, the shallow blind via hole and the deep blind via hole have different energy intensities required for drilling.

Therefore, in the preferred manufacturing method, a reference laser beam having an energy intensity required to form a reference hole which is the shallowest blind via hole is used, and this reference laser beam is applied to the reference hole by one. It is pierced by irradiating twice. On the other hand, a blind via hole deeper than the reference hole is formed by irradiating the reference laser beam a plurality of times.

Therefore, according to the preferred manufacturing method, a large number of blind via holes may be divided into the reference holes and the other blind via holes, and the number of times of irradiation of the reference laser beam may be determined. There are also several types of depths for blind via holes other than the reference holes. The depth of each blind via hole can be known in advance when designing a printed wiring board.

On the other hand, the laser light oscillator is moved to, for example, a coordinate point indicating the position of each blind via hole, and irradiates a reference laser beam each time. The movement and the stop at the coordinate point are performed by N / C control by the positioning coordinate control device. Therefore, for example, by setting the number of times of irradiation of the reference laser light required for each blind via hole to the laser light oscillator positioned by the coordinate control device, the irradiation of the energy intensity required for each blind via hole is performed. Can be.

Therefore, the time required for forming a large number of blind via holes is reduced, and the cost can be reduced. In addition, since it is sufficient for the apparatus to control whether or not the irradiation is performed a plurality of times, the cost of the apparatus can be reduced. Therefore, according to the preferred manufacturing method, it is possible to easily form a large number of blind via holes having different depths only by adjusting the number of irradiations of the reference laser beam.

The depth of the blind via hole is the depth from the outermost surface of the printed wiring board to the inner conductor circuit (including the lowermost lower surface circuit), and each depth corresponds to the distance between the inner conductor circuits. Depending on. This distance is determined by the thickness of the insulating layer provided between the inner conductor circuits. Therefore, the depth of the blind via hole is almost close to an integral multiple of the depth of the reference hole. Therefore, a blind via hole other than the reference hole can be formed by irradiating the reference laser light a plurality of times.

Examples of the insulating layer of the synthetic resin include a synthetic resin alone, a resin base made of a synthetic resin and an inorganic filler, and a cloth base made of a synthetic resin and an inorganic cloth. Examples of the synthetic resin include an epoxy resin, a phenol resin, a polyimide resin, a polybutadiene resin, and a fluorinated resin. An insulating layer made of only these synthetic resins may be formed as a prepreg adhesive layer between other insulating layers.

As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no heat influence. The energy intensity of the reference laser light can be experimentally determined by, for example, the frequency, output (W), and irradiation time of the laser light. The blind via hole is formed up to a desired inner conductor circuit. In the blind via hole thus drilled, a continuous metal plating film is formed from the inner conductor circuit at the bottom thereof to the outer conductor circuit from the wall surface of the blind via hole (see FIG. 10).

Further, the reference laser beam is applied once to all the blind via holes, and thereafter, the reference laser beam is applied only to the blind via holes deeper than the reference holes. It is preferable to irradiate as many times as necessary. As a result, it is possible to obtain an effect that holes of various depths can be formed into holes in a uniform state in the same cycle.

The irradiation of the reference laser beam is performed so that adjacent blind via holes are successively formed. At this time, when the reference hole is formed, one irradiation is performed.
When drilling a blind via hole deeper than that, it is preferable to perform the irradiation as many times as necessary for drilling each time. As a result, movements unnecessary for processing such as table movement can be minimized, so that the entire processing time can be reduced.

The printed wiring board can be used for a printed wiring board requiring high connection reliability, for example, a memory module, a multi-chip module, a mother board, a daughter board, a plastic package and the like.

Next, an inner layer conductor circuit is provided on the surface of the inner layer plate, a blackened film is formed on the surface of the inner layer circuit, and a second conductor circuit is provided on the inner layer plate via an insulating layer.
Next, a method of manufacturing a printed wiring board by irradiating a laser beam to form a via hole from the outermost surface of the insulating layer to the inner layer conductor circuit, and thereafter providing a metal plating film on the inner wall surface of the via hole, It is preferable to use a method of manufacturing a printed wiring board in which an irradiation portion of the circuit irradiated with the laser light has an exposed portion where the blackening film is not provided.

Drilling by a laser beam is performed by irradiating a laser beam to a portion where a via hole is to be formed. As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no thermal effect. The formation of the via hole by the laser beam irradiation is such that the insulating layer is vaporized and removed by the high energy, and a hole is sequentially formed in the printed wiring board. When the tip of the laser beam reaches the inner conductor circuit, the laser beam is reflected by the metal inner conductor circuit. Therefore, the laser beam irradiation is stopped here.

The operation of the preferred manufacturing method will be described. In the preferred manufacturing method described above, the laser beam irradiated portion has an exposed portion having no blackening film on the inner conductor circuit. Therefore, the laser light is reflected by the metal inner conductor circuit and hardly absorbed by the inner conductor circuit. Therefore, abnormal heating of the inner conductor circuit can be prevented. Therefore, the inner conductor circuit is not damaged by heat.

Therefore, in the preferred manufacturing method, the via hole can be formed using laser light without damaging the inner conductor circuit. Also,
Since the via hole is formed by the laser beam, a via hole having a smaller diameter can be obtained, and it becomes easy to manufacture a high-density, high-precision printed wiring board.

As described above, according to the preferred manufacturing method described above, it is possible to provide a method for manufacturing a multilayer printed circuit board, which does not cause damage to the inner layer conductive circuit when forming a via hole by laser light.

The printed wiring board obtained by the above preferred manufacturing method is required to have high connection reliability.
For example, it can be used for memory modules, multi-chip modules, motherboards, daughter boards, plastic packages, and the like.

The exposed portion is preferably formed by forming the blackened film on the inner conductor circuit and then etching the blackened film. Thereby, a blackened film can be easily formed at an arbitrary position.

Alternatively, the exposed portion is formed by partially masking the inner layer conductor circuit when forming the blackened film on the inner layer conductor circuit so that the blackened film is not formed. Is preferred. This makes it possible to easily form the exposed portion when forming the blackened film.

It is preferable that two or more sets of the insulating layer and the second conductor circuit are provided. Thus, a printed wiring board with high-density wiring can be easily obtained.

In the case where there are two or more sets of the insulating layer and the second conductor circuit, a different set of insulating layers and second conductor circuits may be provided on one set of an insulating layer and a second conductor circuit provided on this surface. Another set of two-conductor circuits can be provided (see FIG. 20). That is, the second conductor circuit is formed on the insulating layer, and is formed as a set in a multilayer shape.

In this case, a via hole can be provided from the outermost surface of the insulating layer provided on the outermost side to the surface of any of the second conductor circuits (see FIG. 20). In addition, similarly to the inner conductor circuit, a blackened film is formed on the surface of the second conductor circuit, and the irradiated portion irradiated with the laser beam for forming the via hole is provided with the blackened film. It is preferable to form exposed portions that are not covered (see Reference Example 3).

The printed wiring board obtained by the above-described manufacturing method includes, for example, an insulating layer, an inner conductor circuit provided adjacent to the insulating layer and having a blackened film on its surface, A via hole extending from the outermost surface of the inner layer conductor circuit to the inner layer conductor circuit, and a portion of the inner layer conductor circuit located at the bottom of the via hole is provided with an exposed portion not provided with a blackening film on the inner layer conductor circuit. Printed wiring boards are preferred.

In this printed wiring board, the inner conductor circuit at the bottom of the via hole has no blackened film, and the inner conductor circuit is exposed. In this part, the laser light is hardly absorbed.

Therefore, since the via hole is provided in the insulating layer, abnormal heating of the inner conductor circuit when the insulating layer is irradiated with laser light can be prevented, and damage due to melting of the inner conductor circuit or the like can be prevented. Can be prevented. As described above, according to the printed wiring board, it is possible to provide a multilayer printed circuit board that does not cause damage to the inner conductor circuit when forming a via hole by laser light.

Next, the semiconductor device has two or more insulating layers on the inner conductor circuit and a via hole reaching the inner conductor circuit from the outermost surface of the insulating layer through the two or more insulating layers. A printed wiring board provided with an internal metal plating film for electrically connecting the inner layer conductor circuit and the outermost layer outer conductor circuit provided in the via hole, wherein the opening protrudes into the via hole; An annular intermediate land having a hole is provided, and the diameter of the external via hole on the outer side of the annular intermediate land is larger than the diameter of the internal via hole on the inner layer conductor circuit side. A stepped via hole having a stepped portion is formed, and the inner metal plating film extends along the inner wall surfaces of the outer via hole and the inner via hole. Printed circuit board forming the Jo plated film is preferred.

The preferred printed wiring board will be described. In the printed wiring board, an annular intermediate land having an opening protruding into the via hole is provided. The via hole is a stepped via hole having a stepped portion in the annular intermediate land. Further, the internal metal plating film forms a stepped plating film along the inner wall surface of the external via hole and the internal via hole.

The annular intermediate land is exposed at the step portion of the via hole. The exposed portion has a ring shape having an outer diameter equal to the diameter of the external via hole and an inner diameter equal to the diameter of the internal via hole. Here, the internal plating film contacts while forming a stepped plating film (see FIG. 27 described later).

The internal metal plating film is hardly bonded to the exposed portion of the insulating layer in the via hole, but can be strongly bonded to the annular intermediate land. Therefore, the internal metal plating film is joined to the exposed portion of the annular intermediate land, and thereby can be strongly joined in the via hole. In addition, since the inner diameter side surface of the opening hole of the annular intermediate land is also exposed to the via hole, the internal metal plating film can be joined also at this portion. Therefore, peeling and falling off of the internal metal plating film can be prevented.

By the way, a boundary conductor circuit to be described later may be provided in the boundary portion. When a via hole is formed in a portion where the boundary conductor circuit is not provided, the thickness of the peripheral edge of the opening of the via hole is limited to the boundary portion. Is thinner by the thickness of the boundary conductor circuit than where the boundary conductor circuit is provided. For this reason, a dent corresponding to the thickness of the boundary conductor circuit is formed around the opening of the via hole. By providing the annular intermediate land, the thickness is increased by the thickness of the annular intermediate land and the thickness of the peripheral edge of the opening of the via hole. Therefore, the dent of the peripheral edge of the opening of the via hole can be prevented.

As described above, according to the above, it is possible to provide a printed wiring board in which the internal metal plating film is strongly bonded to the inside of the via hole.

The annular intermediate land is preferably a dummy land that is not connected to a boundary conductor circuit provided at a boundary portion where the two or more insulating layers face each other.
Thereby, even when a large number of insulating layers are stacked and a via hole is provided in a portion where a boundary conductor circuit does not exist in many of these insulating layers, it is possible to prevent dents in the periphery of the opening of the via hole.

The annular intermediate land is preferably a conductive land connected to a boundary conductor circuit provided at a boundary where the two or more insulating layers face each other. Thereby, three or more conductor layers can be connected by a single via hole. Therefore, it is possible to increase the density by reducing the wiring area of vias and lands.

The annular intermediate land is preferably made of a metal such as copper or nickel.

As a method of manufacturing the printed wiring board, for example, two or more insulating layers are provided on the inner conductor circuit, and the outermost surface of the insulating layer is penetrated through the two or more insulating layers. An inner metal plating film for electrically connecting the inner conductor circuit to the outer conductor circuit provided on the outermost surface is provided in the via hole; An annular intermediate land having an opening hole protruding into the inside of the via hole, and a diameter of the via hole of the via hole outside the annular intermediate land is larger than a diameter of the internal via hole on the side of the inner layer conductor circuit. In addition, a stepped via hole having a stepped portion is formed in the annular intermediate land, and the internal metal plating film is formed in the external via hole and the internal vial. A method of manufacturing a printed wiring board which forms a stepped plated film along the inner wall surface of the via hole, the via hole is formed by irradiating a laser beam toward the innerlayer conductor circuit from the outermost surface,
At this time, the laser light penetrates through the opening hole of the annular intermediate land to reach the inner conductor circuit, and the laser light is irradiated to a range necessary for forming the diameter of the external via hole. It is preferable to form the metal plating film after the formation.

According to this manufacturing method, it is possible to obtain a printed wiring board in which the inside of the via hole and the internal metal plating film are strongly bonded as in the case of the above printed wiring board. Further, since the via hole is formed by irradiating a laser beam, a very small via hole having a diameter of 300 μm or less can be easily obtained.

As described above, according to this manufacturing method, it is possible to easily manufacture a printed wiring board having an internal metal plating film strongly bonded to the inside of a via hole and having a small diameter via hole.

[0086] Via hole formation by laser light is performed by irradiating a laser light to a portion where a via hole is to be formed. As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no thermal effect. The formation of the via hole by the laser beam irradiation is such that the insulating layer is vaporized and removed by the high energy, and a hole is sequentially formed in the printed wiring board.

At this time, the laser beam that forms the vicinity of the outer diameter of the via hole is reflected by the annular intermediate land exposed in the via hole. Therefore, the insulating layer existing under the annular intermediate land remains as it is. Also,
The laser beam forming the central portion of the via hole passes through the opening of the annular intermediate land and vaporizes and removes the insulating layer further below. Thereafter, when the laser light reaches the inner conductor circuit, the laser light is reflected by the inner conductor circuit made of metal. Therefore, the irradiation of the laser beam is stopped here.

As described above, the outer diameter of the via hole is larger at the upper part than the annular intermediate land by the laser beam, and the outer diameter at the lower part is smaller than the annular intermediate land. That is, a stepped via hole having a stepped portion can be formed.

It is preferable that the annular intermediate land is a dummy land which is not connected to a boundary conductor circuit provided at a boundary where the two or more insulating layers face each other.
The annular intermediate land is preferably a conductive land connected to a boundary conductor circuit provided at a boundary portion where the two or more insulating layers face each other. In any case, the same operation and effect as described above can be obtained.

Next, the upper conductor circuit is provided on the upper surface of the insulating layer, and the lower conductor circuit is provided on the lower surface thereof. A printed board comprising a blind via hole having a lower conductor circuit as a bottom portion, and a via plating layer for electrically connecting the upper conductor circuit and the lower conductor circuit to the inner wall of the blind via hole. In the wiring board, it is preferable that the lower conductive circuit forming the bottom of the blind via hole has a printed wiring board having a plating solution flow hole having a diameter smaller than that of the blind via hole.

Although the diameter of the plating solution flow hole varies depending on the diameter of the blind via hole, when the diameter of the blind via hole is 0.1 to 0.3 mm, the diameter of the plating solution flow hole is 0.01 mm. It is preferably set to 0.1 mm. Thereby, a uniform via plating layer can be obtained.

If the diameter of the flow hole is less than 0.01 mm, the purpose of flowing the plating solution may not be achieved. On the other hand, if it is larger than 0.1 mm, the holes may not be closed by plating, and there may be a problem that solder leakage occurs during solder filling.

Next, the printed wiring board will be described. The lower conductor circuit forming the bottom of the blind via hole has a plating solution flow hole having a smaller diameter than the blind via hole.

Thus, when the via plating layer is formed, the plating solution can flow into and out of the blind via hole through the plating solution flow hole. For this reason, the plating solution containing a sufficient amount of the plating component is always in contact with the inner wall of the blind via hole, and a uniform via plating layer can be obtained without being mottled. Therefore, it is possible to obtain a printed wiring board having excellent electrical continuity between the upper conductor circuit and the lower conductor circuit, that is, excellent connection reliability between the two.

As described above, it is possible to provide a printed wiring board on which a via plating layer is uniformly formed without being mottled with respect to blind via holes.

The printed wiring board is required to have high connection reliability. For example, a memory module, a multi-chip module, a mother board, a daughter board,
It can be used for plastic packages and the like. Further, the above-described configuration can be applied not only to a printed wiring board having a single insulating layer but also to a printed wiring board having a plurality of layers.

It is preferable that the plating solution flow hole is closed by the via plating layer. Thereby, the amount of solder at the time of solder filling can be made uniform.

The diameter of the plating solution flow hole is preferably 10 to 40% of the diameter of the blind via hole.
Thereby, the plating solution can be sufficiently distributed. On the other hand, if the diameter of the flow hole is less than 10% of the diameter of the blind via hole, the purpose of flowing the plating solution may not be achieved. On the other hand, 4
If it is larger than 0%, the hole may be incompletely closed by plating.

As a method of manufacturing the above printed wiring board, an upper conductive circuit is provided on the upper surface of the insulating layer, and a lower conductive circuit is provided on the lower surface thereof, and the upper conductive circuit is provided between the upper conductive circuit and the lower conductive circuit. A blind via hole penetrating the insulating layer and having the lower conductor circuit at the bottom;
The blind via hole is provided on its inner wall with a via plating layer for electrically connecting the upper conductor circuit and the lower conductor circuit, and the lower conductor circuit constituting the bottom of the blind via hole is provided with a via plating layer. In a method of manufacturing a printed wiring board provided with a plating solution flow hole having a smaller diameter than a blind via hole, the blind via hole is formed by irradiating a laser beam from the upper surface of the insulating layer toward the lower conductive circuit. Make a hole,
Further, at the time of drilling, a plating solution circulation hole is formed in the lower conductor circuit by the laser light, and then a chemical plating solution is caused to flow through the blind via hole and the plating solution circulation hole. It is preferable to form a layer and then perform electroplating while flowing an electroplating solution in the same manner to form the via plating layer.

In this manufacturing method, a via plating layer is formed by performing electroplating while flowing the electroplating solution using the plating solution flowing holes formed in the lower conductor circuit.
Thus, the electroplating solution can sufficiently flow into and out of the blind via hole through the plating solution flow hole. Therefore, a uniform via plating layer can be obtained without being mottled.

Further, since the via hole is formed by the laser beam, a via hole having a smaller diameter can be obtained, and it becomes easy to manufacture a high-density, high-precision printed wiring board.

Drilling by a laser beam is performed by irradiating a laser beam to a portion where a via hole is to be formed. As the laser light, it is preferable to use a carbon dioxide gas laser having a large energy and an excimer laser having no thermal effect. The formation of the via hole by the laser beam irradiation is such that the insulating layer is vaporized and removed by the high energy, and a hole is sequentially formed in the printed wiring board. When the tip of the laser beam reaches the lower conductor circuit, the laser beam is reflected by the metal lower conductor circuit. Therefore, the laser beam irradiation is stopped here.

The energy of the laser beam is high at the center and low at the periphery. Therefore, by using the laser light, it is possible to easily form the plating solution circulation hole at the center of the lower conductive circuit forming the bottom of the blind via hole.

It is preferable that an exposed portion of the insulating layer for forming the plating solution circulation hole (that is, a portion having no inner layer conductor circuit) is provided in advance in the inner layer conductor circuit. Since the lower conductor circuit is made of metal such as copper foil, it reflects laser light. By providing the exposed portion, the insulating layer above the exposed portion is vaporized and removed, so that a plating solution flow hole can be obtained.

A step of forming an upper surface pattern on the upper surface of the insulating substrate at the periphery of the conductive hole forming portion, a step of forming a lower surface pattern for closing the conductive hole forming portion on the lower surface of the insulating substrate, The method for manufacturing a printed wiring board, comprising: a step of forming a conduction hole; and a step of forming a metal plating film by performing a chemical plating process and an electroplating process on an inner wall of the conduction hole. The plating process is performed by flowing a current having a current density of 0.8 to 1.4 A / dm ² through the chemical plating film covering the inner wall of the conduction hole while the insulating substrate is immersed in an electroplating bath. A method for manufacturing a wiring board is preferred.

The operation and effect of the preferred method for manufacturing a printed wiring board will be described. In the above-described manufacturing method, the current density of the current flowing through the chemical plating film is made smaller than that of the conventional method as described above. Therefore, thick film plating can be formed on the inner wall of the conduction hole. therefore,
The mechanical strength of the metal plating film is increased, and the electrical connection reliability of the conduction hole is improved. Further, since a metal plating film having a sufficient thickness can be formed on the inner wall of the conduction hole having a small diameter, high-density mounting of the conduction hole can be realized.

Note that any of the steps of forming the upper surface pattern, forming the lower surface pattern, and forming the conductive holes may be performed in any order, and the order is not specified.

The metal plating film is preferably made of copper. Thereby, a metal plating film having good ductility and low electric resistance can be formed.

It is preferable that the electroplating process is performed twice or more. Thus, a thicker metal plating film can be formed in a short time. Further, the thickness of the metal plating film can be made uniform. On the other hand, when the electroplating process is performed only once, it may take a long time to form a thick metal plating film.

The upper surface pattern and the lower surface pattern refer to any conductive pattern, such as a wiring circuit, a pad, a terminal, and a land, which can be formed on the surface of an insulating substrate. Can be formed. As the insulating substrate, synthetic resin alone,
There are prepreg and the like. Examples of the synthetic resin include an epoxy resin, a phenol resin, a polyimide resin, a polybutadiene resin, and a fluorine resin.

When the printed wiring board is composed of one insulating substrate, it is composed of a laminate of two or more insulating substrates. In the case of a laminate of two or more insulating substrates, the conductor holes may penetrate all the insulating substrates, or may penetrate only some of the insulating substrates.

The printed wiring board can be used for, for example, a memory module, a multi-chip module, a motherboard, a daughter board, a plastic package, and the like.

Further, the above-mentioned hole for the conductor is formed by, for example,
There are a method of irradiating a laser beam to the perforated portion of the insulating layer, a method of chemically melting the perforated portion of the insulating layer, and the like.

Next, a conductor pattern provided on the surface of the insulating substrate, a solder filling hole penetrating through the insulating substrate and reaching the upper surface of the conductor pattern, and a solder filled inside the solder filling hole. Wherein the insulating substrate contains fibers, and the ends of the fibers protrude from the wall surface of the solder filling hole, and the ends of the fibers penetrate into the solder. Printed wiring boards are preferred.

Next, the printed wiring board will be described. The end of the fiber contained in the insulating substrate protrudes from the wall surface of the solder filling hole. The ends of the fibers penetrate into the solder filled in the solder filling holes. Therefore, the solder is strongly bonded to the solder filling hole. Therefore, even when the printed wiring board is mechanically affected from the outside, the solder does not fall out of the solder filling hole.

Further, since the end of the fiber protruding from the wall surface of the solder filling hole cuts into the inside of the solder, the insulating substrate is made of a thin plate of about 0.05 to 0.20 mm and the solder and the wall surface of the solder filling hole are formed. Even when the bonding area with the solder is small, the solder does not fall out of the solder filling hole. For projecting the end of the fiber from the wall surface of the solder filling hole, for example, there is a method of forming the solder filling hole by using a laser beam.

The fibers are preferably at least one of glass fibers, resin fibers, and ceramic fibers. As a result, the force of penetration of the fiber into the solder is improved, and the bonding strength between the solder and the solder filling hole is further improved. The fibers are contained in the insulating substrate, for example, in a felt or cloth state.

As a method of manufacturing the printed wiring board, a method of manufacturing a printed wiring board in which solder is filled in a solder filling hole is as follows. First, a conductive pattern is formed on the surface of an insulating substrate containing fibers. Then, in a portion of the insulating substrate which is not covered with the conductor pattern, a laser beam is irradiated to the conductor pattern to form a hole for filling the solder and to form a hole for the solder filling on the wall surface of the hole for filling the solder. It is preferable that the ends of the fibers contained therein are made to protrude, and then the inside of the solder filling hole is filled with solder.

By forming the solder filling hole by irradiating a laser beam, the end of the fiber is left on the wall surface of the solder filling hole. Therefore, the end of the fiber can be easily protruded from the wall surface of the solder filling hole.

Further, the laser beam can form the solder filling hole only in the insulating substrate, and the conductor pattern covering one opening of the solder filling hole can be left as it is. Therefore, before the formation of the solder filling hole, the conductor pattern can be formed on both the front and back surfaces of the insulating substrate, and the manufacturing process can be simplified.

The fibers are preferably at least one of glass fibers, resin fibers, and ceramic fibers. As a result, the force of penetration of the fiber into the solder is improved, and the bonding strength between the solder and the solder filling hole is further improved. The fibers are contained in the insulating substrate, for example, in a felt or cloth state.

Next, at least two insulating layers are provided, an inner conductor circuit is provided between the insulating layers, and a blind via hole is formed on the outermost surface toward the inner conductor circuit. Preferably, in the printed wiring board in which the inside of the blind via hole is filled with solder, the blind via hole is preferably a printed wiring board whose wall has an uneven cross section.

The printed wiring board will be described below. In the printed wiring board, the cross-sectional shape of the wall surface of the blind via hole is uneven. For this reason, the solder filled in the blind via hole is fixed to this portion by digging into the unevenness. Therefore, the solder can obtain high adhesion strength to the blind via hole.

As described above, according to the above, it is possible to provide a printed wiring board having high adhesion strength of the solder filled in the blind via hole.

The printed wiring board is required to have high connection reliability, for example, a memory module, a multi-chip module, a mother board, a daughter board,
It can be used for plastic packages and the like.

It is preferable that the uneven shape has a concave shape extending in the lateral direction of the blind via hole, a convex shape projecting inward of the blind via hole, or a wavy shape (see FIGS. 52, 54 and 55 described later). ). Thus, the filled solder can be securely brought into close contact with the blind via hole.

It is preferable that the solder filled in the blind via hole is connected to another PC board via a solder ball. As a result, electrical conduction between the PC board and the blind via hole can be reliably ensured. Note that the PC board refers to various substrates on which a printed circuit is formed, and specifically includes a mother board, a daughter board, a memory module, a multi-chip module, a card module, and the like of various devices.

As a method of manufacturing the printed wiring board, at least two insulating layers are provided, and an inner conductor circuit is provided between the insulating layers. A blind via hole, and the inside of the blind via hole is filled with solder. Further, the blind via hole is used for manufacturing a printed wiring board whose wall has an uneven cross section. Preferably, the blind via hole is formed by irradiating a laser beam, and then the molten solder flows into the blind via hole.

According to the above-described manufacturing method, as described above, a printed wiring board in which the cross-sectional shape of the wall surface of the blind via hole is uneven can be manufactured. For this reason, the filled solder filled in the blind via hole can bite into the uneven shape. Therefore, high adhesion strength of the filled solder to the blind via hole can be obtained. Further, since the blind via hole is formed by irradiating a laser beam, the diameter can be made very small, not more than 300 μm.

The formation of the blind via hole by the laser beam is performed by irradiating the portion where the blind via hole is to be formed with the laser beam. As laser light,
It is preferable to use a carbon dioxide laser beam having a large energy and an excimer laser having no thermal effect. In addition, the formation of blind via holes by laser light irradiation
The insulating layer is vaporized and removed by the high energy, and holes are sequentially drilled inward of the printed wiring board. When the tip of the laser beam reaches the inner conductor circuit, the laser beam is reflected by the metal inner conductor circuit. Therefore, the laser beam irradiation is stopped here.

It is preferable that the insulating layer is made of a prepreg in which a resin such as glass cloth is impregnated with a resin, so that a blind via hole having the above-mentioned uneven cross section can be obtained only by irradiating a laser beam. . This is because when the insulating layer is vaporized and removed by the laser beam, the resin portion is removed earlier than the base portion.

Next, it is preferable to form a mounting concave portion by utilizing the above-described technique of piercing by laser beam irradiation. That is, in the method for manufacturing a printed wiring board having a mounting concave portion for mounting an electronic component and a conductor pattern and providing a heat sink at the bottom of the mounting concave portion, the method includes the steps of: Form a pattern,
Next, a heat sink is adhered to the lower surface of the mounting concave portion where the mounting concave portion is formed on the insulating substrate. Then, when forming the mounting concave portion, a laser beam is applied to the upper surface side of the mounting concave portion where the mounting concave portion is formed. Irradiate to drill mounting recesses.

The operation and effect of the above manufacturing method will be described. In the above manufacturing method, as shown in FIG.
After covering the mounting recess forming portion of the insulating substrate with a heat sink, the mounting recess is drilled by laser light irradiation. Therefore, an opening having a desired size can be easily obtained.

In the above manufacturing method, the mounting concave portion is formed by irradiating a laser beam toward the mounting concave portion forming portion, from the surface of the printed wiring board to the heat radiating plate bonded to the opposite side. At this time, the laser light vaporizes and removes the insulating substrate at the mounting concave portion forming portion by the high energy, and sequentially drills holes inside the insulating substrate. Then, when the tip of the laser light reaches the heat sink, the laser light is reflected by the metal heat sink. Therefore, the laser beam irradiation is stopped here. This makes it possible to form a non-penetrating mounting recess in which one of the openings is covered with the heat sink.

Even when the insulating substrate is thin, the mounting recess can be formed without damaging the insulating substrate at all. Furthermore, the bottom of the mounting recess is the surface of the heat sink. Therefore, the electronic component is mounted on the surface of the heat sink inside the mounting recess. Therefore, it is possible to form the mounting concave portion having excellent heat dissipation.

Further, even when a mounting recess penetrating a plurality of insulating substrates is formed, it is not necessary to form a through-hole for forming the mounting recess for each insulating substrate as in the related art.
Furthermore, positioning of each insulating substrate for connecting each through hole is not required. Therefore, according to the above manufacturing method, the mounting concave portion can be formed easily and accurately.

It is preferable that the insulating substrate has two or more insulating layers laminated and has a conductor pattern inside the insulating substrate. Thereby, high-density wiring of the printed wiring board can be realized.

It is preferable that the thickness of the heat radiating plate is 0.01 to 2 mm. As a result, high strength can be obtained at the bottom of the mounting concave portion, and the heat sink can be easily processed. On the other hand, when the thickness is less than 0.01 mm, the strength of the bottom of the mounting recess becomes low, and the heat sink may be broken. If it exceeds 2 mm, processing of the heat sink may be difficult.

As the laser light, for example, a carbon dioxide laser, an excimer laser or the like is used. As the insulating substrate, for example, a synthetic resin alone, a resin base made of a synthetic resin and an inorganic filler, a cloth base made of a synthetic resin and an inorganic cloth, and the like can be used. Examples of the synthetic resin include an epoxy resin, a phenol resin, a polyimide resin, a polybutadiene resin, and a fluorinated resin. An insulating substrate made of only these synthetic resins may be formed as a prepreg or a solder resist between other insulating substrates.

As the inorganic filler added to the synthetic resin, there are glass fiber, silica powder, mica powder, alumina, carbon and the like. A substrate made of a mixture of a synthetic resin and an inorganic filler has a higher strength than a synthetic resin alone. The cloth substrate refers to a substrate made of a cloth woven or knitted in a cloth shape and a synthetic resin, such as a glass epoxy substrate and a glass polyimide substrate. As such a cloth base material, there is a base material in which the cloth is impregnated with a synthetic resin. Examples of the material of the cloth include glass fiber cloth, carbon cloth, and aramid cloth. The same material as described above is used as the synthetic resin.

The conductive pattern refers to a conductive pattern such as a wiring pattern, a pad, a land, a terminal and the like formed in the plane direction of the insulating substrate. The conductor pattern can be formed by etching a metal foil, plating a metal, or the like.

The printed wiring board manufactured by the above method can be used for, for example, a memory module, a multi-chip module, a motherboard, a daughter board, a plastic package, and the like.

[0143]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference Example 1 A method for manufacturing a printed wiring board will be described with reference to FIGS. First, as shown in FIG. 6, a printed wiring board to be manufactured in this example includes three insulating layers 101, 102, and 103 made of synthetic resin and the insulating layers 101 to 101.
3 from the outermost surfaces of the insulating layers 101 to 103 from the inner layer conductor circuits 161, 131.
Blind via hole 14 formed toward 1,131
1,142.

The blind via holes 141, 1
42, the inner layer conductor circuits 161,
Metal plating films 175 and 176 from 131 to the external conductor circuits 153 and 155 are provided. In addition, reference numeral 133
Is the outer conductor circuit on the lower side.

Next, a method of manufacturing the above printed wiring board will be described. First, as shown in FIG. 1A, a first insulating layer 101 is prepared. The first insulating layer 101 is a copper-clad laminate including a resin base 110 and copper foils 105 and 106 adhered to upper and lower surfaces thereof. The resin substrate 110 is a film made of a polyimide resin.

Next, as shown in FIG. 1B, the first insulating layer 101 is etched to form a copper foil 10 on the upper surface.
5 are provided with laser light irradiation holes 151 and 154,
The outer conductor circuits 153 and 155 are formed, and the inner conductor circuit 161 is formed on the lower surface.

It should be noted here that the inner layer conductor circuit 161 has an opening hole 160 at the center thereof as shown in FIGS. Opening hole 160
And the center line of the laser beam irradiation hole 151 coincides (FIG. 3).

Next, as shown in FIG. 1C, first, a second insulating layer 102 using a prepreg as an adhesive sheet is formed.
Then, a third insulating layer 103 separately formed is prepared. The second insulating layer 102 is a glass polyimide material. Also the third
The insulating layer 103 has a cloth substrate 130, an inner conductor circuit 131 formed on the upper surface thereof, and a lower outer conductor circuit 133 formed on the lower surface. As the cloth substrate 130, a glass cloth impregnated with a polyimide resin is used.

Next, as shown in FIG.
03, the second insulating layer 102 and the first insulating layer 1
01 and then thermocompression bonded. This gives
As shown in FIG. 1D, a laminated body 140 in which the above layers are integrally formed and which has laser light irradiation holes 151 and 154 on the upper surface is obtained. Laser light irradiation holes 151 and 15
4 faces the inner layer conductor circuits 161, 131.

Each of the inner conductor circuits 161 and 131 has a diameter of 0.25 mm. The inner conductor circuit 161 has the opening 160 having a diameter of 0.05 mm at the center thereof. This opening hole 160 is 50% of the diameter of the blind via hole (100 μm).

Next, as shown in FIG. 2A, laser light 181 of the same output is simultaneously irradiated from the laser light oscillator 108 toward the laser light irradiation holes 151 and 154. In the laser beam 181, the laser beam irradiation hole 15
The laser beam applied to the substrate 1 pierces while removing the resin base material of the first insulating layer 101 by evaporation. Then, the laser beam 181 finally reaches the inner conductor circuit 161 of copper foil, and forms a shallow blind via hole 141.
Therefore, the laser light 181 is reflected by the inner conductor circuit 161.

At this point, however, the laser light 181 applied to the laser light irradiation hole 154 is still forming the deep blind via hole 142 and has not yet reached the inner layer conductor circuit 131. Therefore, the laser beam 181 is continuously applied to both the inner conductor circuits 161 and 131.

Therefore, as shown in FIG. 7, the laser light 181 applied to the inner conductor circuit 161 passes through the opening 160 provided at the center of the inner conductor circuit 161 to irradiate the second insulating layer 102. . Therefore, FIG.
As shown in FIG. 5, a surplus hole 171 is formed below the opening hole 160. At this time, the inner conductor circuit 1
Since the laser light hitting 61 is weak, it is reflected and does not damage. Then, when the laser light 181 applied to the inner layer conductor circuit 131 reaches the inner layer conductor circuit 131, the laser beam 181 is reflected by the inner layer conductor circuit 131. Therefore, the irradiation of the laser light 181 is stopped.

As the laser light, an excimer laser, a wavelength of 248 nm and an output of 50 W were used. As a result, as shown in FIG.
8mm shallow blind via hole 141 and depth 0.1
A 6 mm deep blind via hole 142 is formed. The diameter of each of the blind via holes 141 and 142 was about 100 μm.

Thereafter, as shown in FIG. 6, metal plating films 175 and 176 are formed from the inside of the blind via holes 141 and 142 to the openings by electroless copper plating. The metal plating films 175 and 176 are formed on the upper surfaces of the inner conductor circuits 161 and 131 and the blind via holes 14.
1, 142 and the openings of the blind via holes in the external conductor circuits 153, 155.
In particular, in the inner layer conductor circuit 161, the metal plating film 1
75 is a surplus hole 17 below the opening hole 160 in the central part.
1 is also formed.

As described above, the inner-layer conductor circuit 1 provided in each layer
61 and 131 to blind via holes 141 and 142
A printed wiring board electrically connected by the metal plating films 175 and 176 provided on the substrate can be obtained.

As described above, according to this embodiment, the opening 160 is formed in the inner conductor circuit 161 provided in the shallow blind via hole. Therefore, even if the inner layer conductor circuit of the already-drilled blind via hole is continuously irradiated with the laser beam 181, the laser beam 1
The central part of 81 has a large energy in the opening 1
60 (FIG. 7). Then, the laser beam 181 that has passed through the opening hole is
Irradiation is performed only on the insulating layer 102. Therefore, in the inner-layer conductor circuit 161, the second insulating layer 102 ahead of the opening hole is slightly opened, but the inner-layer conductor circuit 161 itself is not damaged.

The inner conductive circuit 131 in the deep blind via hole 142 stops irradiation when the laser beam 181 is reflected, so that no damage occurs. Each of the blind via holes 1 thus formed with different depths
Metal plating films 175 and 176 are formed inside 41 and 142 as in the prior art. At this time,
As described above, none of the inner-layer conductor circuits is damaged by the laser beam, so that the state of insufficient metal plating film formation as shown in the conventional example can be avoided.
A metal plating film having excellent conductivity can be formed.

Reference Example 2 A method for manufacturing a printed wiring board according to a reference example will be described with reference to FIGS. First, as shown in FIGS. 8 and 9, the printed wiring board 210 to be manufactured in this example has three insulating layers 211 and 212 made of synthetic resin.
213 and inner via conductor circuits 221 to 225 provided between the insulating layers 211 to 213 are provided with blind via holes 3A to 3E formed from the outermost surface of the printed wiring board 210 toward the inner conductor circuits 221 to 225.

As shown in FIG. 10, the inner walls of the blind via holes 3A to 3E are respectively provided with metal platings from the inner layer conductor circuits to the respective outer conductor circuits 216 provided on the upper surface of the printed wiring board. A membrane 296 is provided. In FIG. 8, reference numeral 224 denotes a lower surface conductor circuit on the lower surface of the printed wiring board, but is referred to as an inner layer conductor circuit here.

As can be seen from a comparison between FIGS. 8 and 9, the printed wiring board 210 has one as shown in FIG.
Blind via holes are provided at the intersections of rows の 5 and columns AE. For example, in the YY cross section of FIG. 9, blind via holes 3A to 3E having different depths are provided as shown in FIG.

Of these, 3A and 3C correspond to the reference holes which are the shallowest blind via holes, 3B and 3E correspond to the deeper blind via holes, and 3D corresponds to the deepest blind via hole. In addition, 3A-3E
Indicates blind via holes in columns A to E in the third row shown in FIG.

Next, a method of manufacturing the above printed wiring board will be described. That is, first, the reference laser beam 242 having the energy intensity necessary for drilling the reference holes 3A and 3C, which are the shallowest blind via holes, is used. When the reference holes 3A and 3C are drilled, the reference laser beam 242 is used. Irradiation is performed once, and when drilling the blind via holes 3B, 3D, 3E deeper than that, the reference laser beam 242 is irradiated a plurality of times.

The printed wiring board 210 is manufactured by forming an inner conductor circuit and an insulating layer for each layer by a subtractive method or the like, laminating the layers, and thermocompression bonding. And the outer inner layer conductor circuit 2 on the upper surface.
16 has an opening 206 for forming a blind via hole reaching the inner conductor circuits 221 to 225, and the opening is irradiated with the reference laser beam 242. In this example, glass polyimide is used for the insulating layer.

Next, as shown in FIG. 8, the laser light oscillator 241 for emitting the reference laser light 242 is used to control the movement of the laser light oscillator 241 to each irradiation position, that is, the position of the blind via hole to be formed. It is electrically connected to the coordinate control device 245. The laser light oscillator has an XY moving device (not shown) that moves in the column and row directions, that is, the XY direction, as shown in FIG. The X-
The movement of the Y moving machine is controlled by the coordinate control device 245, and the laser beam oscillator 24 irradiates the reference laser beam 242 to the position where the blind via hole is to be formed.
Stop 1

The laser light oscillator 241 has an oscillator for irradiating the reference laser light 242 in a spot manner, and has an adjuster for adjusting the energy intensity of the reference laser light 242 as necessary. The reference laser beam 242 irradiating the same type of printed wiring board
Since the energy intensities of the printed wiring boards are the same, the above-described adjuster adjusts the printed wiring boards as needed for each different type.

In this example, the reference laser beam was a CO ₂ laser, a wavelength of 10.6 μm, and an output of 3000.
W, a single irradiation time of 0.01 second was used. This gives
As shown in FIG.
The reference holes 3A and 3C which are the shallowest blind via holes of 08 mm, the deep blind via holes 3B and 3E of 0.16 mm in depth, and the deeper blind via holes 3D are formed. The blind via holes 3A-3
The diameter of each E was about 100 μm.

When drilling the blind via hole, the reference hole 3 which is the shallowest blind via hole
The reference holes 3A and 3C are formed by using a reference laser beam 242 having an energy intensity necessary for forming the holes A and 3C.
, The reference laser beam 242 is irradiated once to pierce it. Further, the reference laser beam 242 is applied twice to the blind via holes 3B and 3E which are deeper than the reference holes. For deeper blind via holes, the reference laser beam
Irradiate twice.

As described above, according to the present embodiment, the number of times of irradiation of the reference laser beam 242 may be determined by dividing a large number of blind via holes into the reference holes 3A and 3C and the other blind via holes. The blind via holes other than the reference holes 3A and 3C also have several types of depths.
It can be known in advance when designing the printed wiring board 210. Therefore, the number of irradiations for each blind via hole can be set in advance.

The laser light oscillator 241 moves to the coordinate point indicating the position of each blind via hole (FIG. 8), and irradiates the reference laser light 242. The movement and the stop at the coordinate point are performed by the N / C control of the XY moving device by the coordinate control device 245 for positioning. In this example, a method is employed in which the reference laser beam is sequentially radiated to the adjacent blind via holes, and is irradiated once (reference hole) or a plurality of times depending on the depth.

After the above drilling, as shown in FIG.
A metal plating film 296 is formed from the inside of the blind via holes 3A to 3E to the openings by electroless copper plating. The metal plating film is formed on the inner conductor circuits 221-2.
25, the wall surface of each blind via hole, and the opening of the blind via hole in the external conductor circuit 216.

As described above, according to the present embodiment, the reference laser beam may be irradiated once or a plurality of times in accordance with the depth of the blind via hole, so that the time required for forming many blind via holes is reduced. , Cost can be reduced. In addition, since it is sufficient for the apparatus to control whether or not the irradiation is performed a plurality of times, the cost of the apparatus can be reduced. Also, many blind via holes having different depths can be easily formed.

Reference Example 3 A printed wiring board and a method of manufacturing the same will be described with reference to FIGS.
4 will be described. As shown in FIG. 20, the printed wiring board 301 of this example has insulating layers 329 and 328 and a blackening film 340 provided on the surface adjacent to the insulating layer 329.
And a via hole 30 extending from the outermost surface of the insulating layer 329 to the inner conductor circuit 304.
And 3. Further, an exposed portion 349 where the blackening film 340 is not provided in the inner layer conductor circuit 304 is formed at a portion of the inner layer conductor circuit 304 located at the bottom of the via hole 303.

Next, the details of the printed wiring board 301 will be described. As shown in FIG.
01 is an inner plate 319 provided with the inner conductor circuit 304,
It comprises two insulating layers 329 and 328 laminated on both surfaces of the inner layer plate 319, respectively, and second conductor circuits 306 and 360 provided on the surfaces of the insulating layers 329 and 328, respectively. The second conductor circuit 360 serves as an outer conductor circuit in the printed wiring board 301.

The inner layer plate 319 is provided with a through hole 315 filled with the solder 305, and the through hole 315 ensures conduction of the inner layer conductor circuits 304 provided on both sides of the inner layer plate 319.

The inner layer conductor circuit 304 is made of a copper foil pattern 3
41 and a metal plating film 342 provided on the surface of the copper foil pattern 341. Further, as described later, a blackening film 340 is provided in order to secure adhesion between the insulating layer 329 and the insulating layer 329 laminated thereon. In forming the via hole 303, the insulating layer 329 is irradiated with laser light. This irradiated part forms an exposed part 349 where the blackening film 340 is not provided.

On both sides of the inner layer plate 319, the insulating layer 3
29 are provided. The second conductor circuit 306 is provided on the surface of the insulating layer 329. The inner layer conductor circuit 30
4, the second conductor circuit 306 also has a copper foil pattern 3
61 and a metal plating film 362, and a blackened film 340 and an exposed portion 349 are provided on the surface of the second conductive circuit 306 in the same manner.

Next, the insulating layer 329 is provided with another insulating layer 328, and on the surface thereof, a second conductor circuit 360 serving as an outer conductor circuit. The insulating layer 328 has a via hole 303 extending from the outermost surface to the second conductive circuit 306. Solder balls 381 are provided on the surface of the insulating layer 328 and the via holes 303. The surface of the second conductor circuit 360 is covered with a solder resist 382.

In manufacturing the printed wiring board 301, the inner conductor circuit 304 is provided on the surface of the inner board 319 (FIG. 13), and the blackening film 340 is formed on the surface of the inner conductor circuit 304 (FIG. 14). . Next, a second conductor circuit 306 is formed via the insulating layer 329, and the inner conductor circuit 304 is irradiated from the outermost surface of the insulating layer 329 by irradiating a laser beam.
Is provided. Thereafter, a metal plating film 212 is provided on the inner wall surface of the via hole 303 (FIG. 1).
8).

Next, details of the above manufacturing method will be described. First, as shown in FIG. 11, a copper-clad laminate 307 having a copper foil 370 on its surface is prepared. Next, as shown in FIG. 12, the copper foil 370 is patterned by etching to form a copper foil pattern 341. Thereafter, a through hole 315 is provided in the copper clad laminate 307.

Next, as shown in FIG. 13, a metal plating film 342 by electroless copper plating is provided on the inner wall surface of the through hole 315 and the copper foil pattern 341. Thus, the inner conductor circuit 304 electrically connected to the through hole 315 was obtained. After that, the through holes 315 are filled with solder 305.

Next, as shown in FIG. 14, a blackening film 340 is formed on the inner layer conductor circuit 304 by a blackening process. The blackening process will be described with reference to another drawing below. First, as shown in FIG.
A film 345 is provided on the entire surface of the substrate. Next, the film 345 is removed by etching except for the portion provided on the surface of the inner conductor circuit 304 in the portion to be the exposed portion 349. Thus, a mask 346 is obtained.

Next, by chemically treating the surface of the inner layer conductor circuit 304, as shown in FIG. 22, the surface of the metal plating film 342 is oxidized to form a blackened film 340 made of black copper oxide. You. However, the mask 34
6 is not oxidized, so the blackened film is 340
Was not formed. Thereafter, the mask 346 is removed by etching. Thus, as shown in FIG. 14, an exposed portion 349 is formed.

Next, as shown in FIG.
A prepreg 378 and a copper foil 370 are laminated on both surfaces of the substrate 19 and pressed. As a result, as shown in FIG. 16, a laminate including the inner layer plate 319, the insulating layer 329, and the copper foil 370 is obtained. Next, as shown in FIGS. 17 and 23, the copper foil 370 is patterned to form a copper foil pattern 361. Next, as shown in FIG. 24, a laser beam is irradiated to form a via hole 303 in the insulating layer 329.
Note that an excimer laser, a wavelength of 248 nm, and an output of 50 W are used as the laser light.

Next, as shown in FIG. 18, a metal plating film 362 is formed on the inner wall surface of the via hole 303 and the copper foil pattern 361 in the same manner as the electroless plating performed on the copper foil pattern 341. I do. Further, a blackening film 340 is provided on the second conductor circuit 306 in the same manner as the blackening process performed on the inner-layer conductor circuit 304.

Next, the insulating layer 329 and the second conductor circuit 306 are provided in the same manner as in the case where the insulating layer 329 and the second conductor circuit 306 are provided.
As shown in FIG. 19, an insulating layer 328, a via hole 303, and a second conductor circuit 360 are formed on the surface of the substrate. Thereafter, as shown in FIG. 20, a solder ball 381 is provided for the second conductor circuit 360 and the via hole 303, and a solder resist 382 is provided between the solder balls 381. Thus, the printed wiring board 1 is obtained.

Next, the operation and effect of this embodiment will be described. In the manufacturing method according to the present example, as shown in FIG. 17, the exposed portion of the laser beam forms an exposed portion 349 without the blackening film 340 on the inner conductor circuit 304. Therefore, the laser light is not absorbed by the inner conductor circuit 304. Therefore, the inner conductor circuit 304 is not damaged by heat.

Therefore, the via hole 303 can be formed using laser light without damaging the inner conductor circuit 304. Further, since the via hole 303 is formed by laser light, a via hole with a smaller diameter can be obtained.

In this embodiment, the via hole 303 extending from the outermost surface of the insulating layer 328 to the second conductive circuit 306 is also formed by irradiating a laser beam in the same manner as the via hole 303. The laser light is irradiated on the exposed portion 369 without the blackening film 340 in the inner conductor circuit.
Is formed. Therefore, the same effect as the via hole 303 can be obtained for the via hole 3030.

Reference Example 4 This example is a method of manufacturing a printed wiring board in which a copper foil pattern is provided by plating, as shown in FIGS.

First, through the same process as in Reference Example 3,
Through hole 315 and inner layer conductor circuit 3 from copper clad laminate
An inner layer plate 319 provided with the substrate 04 is formed. Further, the blackened film 340 and the exposed portion 34 are
9 is formed.

However, the blackening film 340 and the exposed portion 34
9 beforehand, the inner layer conductor circuit 304
After the blackening film 340 is provided on the entire surface of the
An exposed portion 349 is formed by selectively etching an unnecessary portion of 40.

Next, the insulating layers 3 are formed on both sides of the inner layer plate 319.
29 are formed. Next, as shown in FIG. 25, the insulating layer 329 is irradiated with a laser beam to
03 is formed. Next, the surface of the insulating layer 329 is roughened by physical polishing or chemical treatment (chemical solution) to obtain a roughened surface 348. Next, the roughened surface 3
A mask is provided for 48, and electroless plating is performed. Then, the mask is removed. Thus, a copper foil pattern 341 as shown in FIG. 26 was obtained.

Thereafter, in the same manner as in Reference Example 3, a metal plating film 342 is provided on the copper foil pattern 341 and the inner wall surface of the via hole 303, and a second conductive circuit 306 electrically connected to the via hole 303 is formed. Further, the insulating layer 32
9. A solder ball, a solder resist, and the like are formed in the via hole 303. As described above, Reference Example 3 and FIG.
A printed wiring board as shown at 0 is obtained. Others
This is the same as Reference Example 3.

In the method of manufacturing a printed wiring board of this example, since the resin was used for the insulating layer, the insulating thickness was reduced to 40 μm.
m, which is suitable for making the printed wiring board thinner and lighter. Others have the same functions and effects as in Reference Example 3.

Reference Example 5 A printed wiring board according to a reference example and a method of manufacturing the same will be described with reference to FIGS. FIG. 27, FIG.
As shown in the figure, the printed wiring board 401 of this example has two insulating layers 418 and 416 on the inner layer conductor circuit 461, and two insulating layers 41 from the outermost surface of the insulating layer 416.
8, and a via hole 402 penetrating through the inner conductor circuit 461 through the inner conductor circuit 461. On the inner wall of the via hole 402,
The inner conductor circuit 461 and the outer conductor circuit 46 provided on the outermost surface
2 is provided with an internal metal plating film 405 for electrically connecting the second metal film 2 to the second metal film.

As shown in FIGS. 27 and 28, the printed wiring board 401 is provided with an annular intermediate land 404 having an opening hole 440 projecting into the via hole 402. Further, the via hole 402 is formed in the annular intermediate land 4.
The diameter of the external via hole 453 on the outer side than that of the inner via hole 454 is larger than the diameter of the internal via hole 454 on the inner layer conductor circuit 461 side, and a stepped via hole having a stepped portion 452 is formed in the annular intermediate land 404. Further, the inner metal plating film 405 has the outer via hole 453, the inner via hole 4
The stepped plating film 450 is formed along the inner wall surface of the step 54. The via hole 402 is a blind via hole.

Next, the details of the printed wiring board 401 will be described. As shown in FIG. 27, the printed wiring board 401 includes an inner layer board 419 provided with an outer layer conductor circuit 462 and an inner layer conductor circuit 461, two insulating layers 418 and 416 provided on the surface of the inner layer conductor circuit 461, and The boundary conductor circuit 463 and the annular intermediate land 4 provided on the surface of the layer 418
04 and the outer layer conductor circuit 46 provided on the surface of the insulating layer 416.
It consists of two. As shown in FIG. 28, the annular intermediate land 404 is a conductive land connected to the boundary conductor circuit 463.

The printed wiring board 401 has an insulating layer 416
Via hole 4 reaching inner conductor circuit 461 from the outermost surface of
02 is provided. The via hole 402 includes an external via hole 453, an internal via hole 454, and a step portion 452 existing therebetween.

The inner wall surface 20 of the via hole 402 is
16,418 are exposed. In addition, both insulating layers 418, 4
16, that is, from the step portion 452 to the annular intermediate land 40.
4 is exposed, and an exposed portion 441 is formed here. Further, an inner diameter portion of the opening hole 440 of the annular intermediate land 404 is also exposed in the via hole 402.

Here, the inner metal plating film 405 is
Although it is also joined to the inner wall surface 420 of the via hole 402,
As shown in FIG. 27, the outer conductor circuit 462 mainly located at the periphery 425 of the opening of the via hole 402, the exposed portion 411 of the annular intermediate land 404, the side surface of the opening hole 440, and the inner conductor circuit 461 facing the bottom of the via hole 402
In a joined state.

As shown in FIG. 27, the annular intermediate land 404 has an outer diameter larger than the diameter of the external via hole 453, and has the same diameter as the diameter of the internal via hole 454.
Having. The annular intermediate land 404 is formed by etching copper foil integrally with the boundary conductor circuit 463 at the same time.

In manufacturing the printed wiring board 401 according to the present example, the via holes 402 are formed by irradiating a laser beam from the outermost surface of the insulating layer 416 to the inner layer conductor circuit 461 as shown in FIG. At this time, the laser beam is applied to the opening 440 of the annular intermediate land 404.
To reach the inner conductor circuit 461, and irradiate the laser beam to a range necessary for forming the diameter of the external via hole 453. Then, after forming the via hole 402, the internal metal plating film 405 is formed.

Next, the details of the above manufacturing method will be described. First, a copper-clad laminate having a copper foil on the surface is prepared, and the copper foil is patterned. Next, a copper plating film is formed on the copper foil, and an inner conductor circuit 461 and an outer conductor circuit 462 are formed on the surface of the inner plate 419 as shown in FIG.

Next, a prepreg and a copper foil are laminated on the surface of the inner conductor circuit 461 in the inner board 419. Next, the copper foil is patterned, and then a copper plating film is provided on the copper foil. Thus, an insulating layer 418 having the boundary conductor circuit 463 and the annular intermediate land 404 is obtained. At this time, an exposed portion of the insulating layer 418, which is a laser light irradiation portion 472 described later, is also formed.

Next, the insulating layer 416 having the outer inner conductor circuit 462 is formed on the surface of the insulating layer 418 in the same manner as described above.
To form Similarly, at this time, an exposed portion of the insulating layer 418 which is a laser light irradiation portion 471 to be described later is also formed.

The irradiation units 471 and 472 are concentric as shown in FIG. 29, and the irradiation unit 472 is smaller than the irradiation unit 471. The irradiation part 471 has the same diameter as the outer via hole 453, and the irradiation part 472 has the inner via hole 45.
4 and the same diameter. The irradiation part 472 is also inside the opening 440 of the annular intermediate land.

Next, as shown in FIG.
Is irradiated with laser light. As a result, the laser beam reaches a portion of the annular intermediate land 404, and is irradiated by the irradiation portion 47.
The outer via hole 453 is formed by vaporizing and removing the insulating layer 416 below the first insulating layer 416.

[0209] Since the annular intermediate land 404 is made of metal, the reflectance of the laser light is high. Therefore, the laser light hitting the exposed portion 441 of the annular intermediate land 404 is reflected here, and the insulating layer 418 existing below the exposed portion 441.
Remains without being vaporized and removed. On the other hand, opening hole 4
The inside of 40, that is, the irradiation part 472 is in a state where the insulating layer 418 is exposed. Therefore, the insulating layer 418 in this portion is vaporized and removed by the laser light, and an inner via hole 454 is formed. The laser beam is blocked by the inner conductor circuit 461 and does not reach below it.

Thereafter, as shown in FIG. 27, the internal metal plating film 4 is formed in the via hole 402 by electroless copper plating.
05 is formed. Thus, the printed wiring board 401 according to this example is obtained.

In the present example, the via hole 402
Is an opening hole 4 of the annular dummy land 404 having a diameter of 100 μm.
40 has a diameter of 100 μm and an outer diameter of 200 μm. Excimer laser, wavelength 24
8 nm and an output of 50 W are used.

Next, the operation and effect of this embodiment will be described. In the printed wiring board 401 of this example, an annular intermediate land 404 having an opening hole 440 protruding into the via hole 402 is provided. In addition, via hole 402
Is a stepped via hole having a stepped portion 452 in the annular intermediate land 404. Furthermore, the internal metal plating film 405
Form a stepped plating film 450 along the inner wall surface 420 of the external via hole 453 and the internal via hole 454.

The annular intermediate land 404 is a via hole 402
Has an exposed portion 441 in the step portion 452. The exposed portion 441 has a ring shape having an outer diameter equal to the diameter of the external via hole 453 and an inner diameter equal to the diameter of the internal via hole 454. Here, the internal plating film 405 contacts while forming a stepped plating film 450 (see FIG. 27).

The inner metal plating film 405 is hardly bonded to the exposed portions of the insulating layers 418 and 416 in the via hole 402, but the annular intermediate land 404 made of a copper plating film is difficult.
Can be strongly bonded. Therefore, the inner metal plating film 405 is formed on the exposed portion 44 of the annular intermediate land 404.
1, thereby enabling strong bonding inside the via hole 402. Further, since the inner diameter side surface of the opening hole 440 of the annular intermediate land 404 is also exposed to the via hole 402, the internal metal plating film 405 can be joined also in this portion. Therefore, the inner metal plating film 4
05 can be prevented from peeling off.

The printed wiring board 401 according to this example
Since the via hole 402 is formed by irradiating a laser beam, the diameter can be made extremely small.

Reference Example 6 As shown in FIG. 30, this example has three insulating layers 413 to 413.
15 is a printed wiring board 408 having a via hole 403 penetrating therethrough.

That is, the printed wiring board 408 according to this example
Comprises an inner layer plate 419 and three insulating layers 413 to 415 provided on the inner layer plate 419. An inner conductor circuit 461 and an outer conductor circuit 462 are provided on the surface of the inner plate 419. The outer conductor circuit 462 is provided on the insulating layer 415. Boundary conductor circuits 464 and 465 are provided at boundary portions 417 where the insulating layers 413 to 415 face each other.

The via hole 403 is a stepped via hole having a stepped portion 452 at the two annular intermediate lands 449 and 404. The via hole 403 is located at the annular intermediate land 4
49, an external via hole 457 outside of the annular intermediate land 449, an intermediate via hole 458 between the annular intermediate lands 449 and 404, and an internal via hole 459 inside the annular intermediate land 404. Then, an internal plating film 405 is formed in the via hole 403.

At the periphery of the via hole 403, annular intermediate lands 404 and 449 projecting into the via hole 403 are provided in different layers. The annular intermediate land 449 provided in the upper layer is a dummy land not connected to the boundary conductor circuit 465, and has a ring shape. On the other hand, the annular intermediate land 404 provided in the lower layer is a conductive land connected to the boundary conductor circuit 464.

Further, the annular intermediate lands 449 and 404 have opening holes 447 and 440, respectively. The diameter of the opening hole 447 is equal to the diameter of the intermediate via hole 458,
Is equal to the diameter of the internal via hole 459.

Here, the inner metal plating film 405 is
Although it is also joined to the inner wall surface 430 of the via hole 403,
The outer conductor circuit 462 mainly located at the peripheral edge 435 of the via hole 403, the exposed parts 448 and 441 of the annular intermediate lands 449 and 404, the opening holes 440 and 447, and the inner conductor circuit 461 facing the bottom of the via hole 403. It is in. The via hole 403 is a blind via hole that is covered on one side.

The printed wiring board 408 has an insulating layer 4
A via hole 426 is provided that penetrates through the hole 15 and reaches the boundary conductor circuit 464. The structure of the via hole 426 is similar to the structure of the via hole of Reference Example 5. Note that the annular intermediate land 404 over the via hole 426 is a conductive land connected to the boundary conductor circuit 465. Others are the same as in Reference Example 5.

In this example, by providing the annular dummy land 449 in a portion where the boundary conductor circuit 465 does not exist, the annular dummy land 449 compensates for the thickness of the connection conductor circuit 465 and prevents the dent of the opening edge 435 of the via hole 403. Can be. In other respects, according to this embodiment, the same operation and effect as those of the fifth embodiment can be exhibited.

Embodiment 1 A printed wiring board according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG.
The printed wiring board 501 of this example has two insulating layers 518 and 516 laminated on both surfaces of the inner conductor circuit 562, and
Two insulating layers 518 and 516 from the outermost surface of the insulating layer 516
Via hole 50 that penetrates through and reaches inner conductor circuit 562.
2 In the via hole 502, an internal metal plating film 521 for electrically connecting the inner conductor circuit 562 and the outer conductor circuit 561 is provided. The via hole 502 is a blind via hole.

As shown in FIG. 32, at the boundary 517 where the two insulating layers 518 and 516 face each other,
An annular dummy land 504 for reinforcement having an opening 540 is provided around the via hole 502. The annular dummy land 504 is joined to the internal metal plating film 521.

Next, details of the printed wiring board 501 will be described. As shown in FIG. 31, the printed wiring board 501
Is an inner layer plate 519 provided with an inner layer conductor circuit 562, and two insulating layers 5 laminated on both surfaces of the inner layer plate 519, respectively.
18, 516 and the inner conductor circuit 563, the annular dummy land 504, and the insulating layer 51 provided on the surface of the insulating layer 518.
6 and an outer layer conductor circuit 561 provided on the surface of the substrate. Note that a through hole 528 is provided in the inner layer plate 519. In the through hole 528, a metal plating film 505 for electrically connecting the two inner conductor circuits 562 provided on both surfaces of the inner plate 519 to each other is provided.

The printed wiring board 501 has via holes 502 reaching the inner conductor circuit 562 from the outermost surface of the insulating layer 516, and the inner conductor circuit 5 from the outermost surface of the insulating layer 516.
A via hole 529 reaching 63 is provided. The via hole 502 is formed in a portion where the inner conductor circuit 563 does not exist.

The insulating layers 516 and 518 are exposed on the inner wall surface 520 of the via hole 502, and the opening 540 of the annular dummy land 504 is exposed from between the insulating layers 518 and 516. Here, the internal metal plating film 521 is also joined to the inner wall surface 520 of the via hole 502, but the outer layer conductor circuit 561, which exists mainly on the opening edge 525 of the via hole 502, the opening hole 540 of the annular dummy land 504,
Then, the inner conductor circuit 5 facing the bottom of the via hole 502
62 is in a joined state.

The annular dummy land 504 is made of copper plating, has an outer diameter larger than the diameter of the via hole 502, and has an opening 540 having the same diameter as the diameter of the via hole 502, as shown in FIG. In addition, the annular dummy land 504
Are formed by etching when the inner conductor circuit 563 is formed. The annular dummy land 504 is a reinforcing land provided separately so as not to conduct with the inner conductor circuit 563.

Further, the via hole 529 is formed in the insulating layer 516.
To reach the inner-layer conductor circuit 563. An internal metal plating film 521 is also provided inside the via hole 529. Internal metal plating film 5
Reference numeral 21 denotes an inner-layer conductor circuit 561 provided mainly on the periphery 25 of the opening of the via hole 529, and an inner-layer conductor circuit 516 facing the inner wall of the via hole 529 and the bottom of the via hole 529.
Is in a joined state.

Next, a method of manufacturing a multilayer printed circuit board according to this example will be described. First, a copper-clad laminate having a copper foil on the surface is prepared, and the copper foil is patterned. Then,
Perforations are made in the copper clad laminate to form through holes 528.
Next, a metal plating film is formed in the through hole 528 by electroless copper plating. As described above, through hole 5
28 and an inner layer plate 519 having an inner layer conductor circuit 562.

Next, a prepreg and a copper foil are laminated on the surface of the inner layer plate 519. Next, the insulating layer 518 having the inner conductor circuit 563 and the annular dummy land 504 is formed by patterning the copper foil by etching.
Next, in the same manner as described above, a prepreg and a copper foil are laminated on the surface of the insulating layer 518, and the copper foil is patterned.
As described above, the insulating layer 5 having the outer inner layer conductor circuit 561
16 is obtained.

After that, laser light is irradiated from the outermost surface of the insulating layer 516. At this time, the laser beam penetrates through the opening 540 of the annular dummy land 504 and reaches the inner conductor circuit 562. Thus, a via hole 502 reaching the inner layer conductor circuit 562 and a via hole 529 reaching the inner layer conductor circuit 563 are formed. Thereafter, an internal metal plating film 505 is formed in the via holes 502 and 529 by electroless copper plating. Thus, the printed wiring board 501 according to this example is obtained.

The via holes 502 and 529 have a diameter of 1
The opening hole 540 of the annular dummy land 504
Has a diameter of 100 μm and an outer diameter of 200 μm. Also, as the laser light, an excimer laser, a wavelength of 248 nm,
An output of 50 W is used.

Next, the function and effect of this embodiment will be described. In the printed wiring board 501 of this example, an annular dummy land 504 is provided around the via hole 502, and the annular dummy land 504 is joined to the internal metal plating film 521 in the via hole 502.

The internal metal plating film 521 is
Although it is difficult to join to the exposed portions of the insulating layers 518 and 516 in 2 and the joining strength is weak, it can be strongly joined to the annular dummy land 504. Therefore,
The internal metal plating film 521 can be strongly bonded in the via hole 502. Therefore, the internal metal plating film 52
1 can be prevented from peeling off.

Also, the printed wiring board 501 according to this embodiment
Since the via holes 502 and 529 are formed by irradiating a laser beam, the diameter can be made extremely small.

Embodiment 2 In this embodiment, as shown in FIG. 33, five insulating layers 511 to 5
15 is a printed wiring board 508 having a via hole 503 penetrating therethrough. The printed wiring board 508 includes the inner layer board 51.
It is a laminate in which nine and five insulating layers 511 to 515 are laminated. On the surface of the inner layer plate 519, an inner layer conductor circuit 562 and an outer layer conductor circuit 561 are provided. The outer layer conductor circuit 561 is provided on the insulating layer 515.

Also, at the boundary 517 where the insulating layers 511 to 515 face each other, the inner conductor circuits 563 and 564 are provided.
Is provided. One inner layer conductor circuit 563 is non-conductive with the via hole 503 and the other inner layer conductor circuit 564
Are electrically connected to the via hole 503. The via hole 503 is provided so as to penetrate the inner conductor circuit 564.

The via holes 503 are formed in the insulating layers 511 and 51.
2, 514, the portion without the inner conductor circuit 563,
Reinforcing annular dummy land 504 having opening 540
Is provided in the portion provided with. Here the via hole 5
The inner metal plating film 521 provided inside the via hole 503 is also joined to the inner wall surface 530 of the via hole 503. Then, the inner conductor circuit 56 facing the bottom of the via hole 503
2 is in a joined state. Other configurations are the same as those of the first embodiment.

In the printed wiring board 508 of this example, inner layer conductor circuits 563 and 187 are provided at a boundary portion 517 where different insulating layers 511 to 515 are in contact. The via hole 503 is formed in a portion where the inner-layer insulating circuit 564 is provided without the inner-layer conductor circuit 563.

If the annular dummy land 504 does not exist, the peripheral edge 535 of the opening of the via hole 503 is depressed by the thickness of the inner conductor circuit 563 formed in the insulating layers 511, 512, and 514. However, the printed wiring board 508 of this example is not
Since the metal film 04 is provided, the metal plating film 521 is strongly bonded, and dents and the like do not occur at the peripheral edge 535 of the opening of the via hole 503. Others have the same operation and effects as those of the first embodiment.

Reference Example 7 A printed wiring board and a method of manufacturing the same according to Reference Example 7 will be described with reference to FIGS. As shown in FIG. 37, the printed wiring board of this example has an upper conductor circuit 621 on the upper surface of an insulating layer 619 and a lower conductor circuit 6 on the lower surface thereof.
22 are provided. In addition, between the upper conductor circuit 621 and the lower conductor circuit 622, a blind via hole 61 penetrating the insulating layer 619 and having the lower conductor circuit 622 as a bottom.
5 is provided. The diameter of the blind via hole 615 is 0.2 mm.

The blind via hole 615 has an upper conductor circuit 621 and a lower conductor circuit 62 on its inner wall.
Via plating layer 616 for electrical connection between
Is provided. The lower conductor circuit 622 forming the bottom of the blind via hole 615 has a plating solution flow hole 6 having a smaller diameter than the blind via hole 615.
11 are provided. The diameter of the plating solution flow hole 611 is 0.0
3 mm. The plating solution circulation hole 611 is formed in the via plating layer 6.
It is closed by 16.

In manufacturing the printed wiring board 601, the blind via holes 615 are pierced by irradiating the lower conductor circuit 622 with laser light from the upper surface of the insulating layer 619. At 622, a plating solution flow hole 611 is formed. Next, the chemical plating solution was added to the blind via hole 61.
5 and the plating solution flowing hole 611,
A chemical plating hole 617 is formed in the blind via hole 615.

Thereafter, similarly, electroplating is performed while flowing an electroplating solution to form a via plating layer 616. The chemical plating holes 617 are provided so that the via plating layer 616 can be easily formed in the blind via holes 615.

Next, the details of the above manufacturing method will be described. As shown in FIG. 34, a copper-clad laminate 609 comprising an insulating layer 619 and a copper foil 620 is prepared, and the copper foil 6
20 is patterned. Thereby, the upper conductor circuit 6
21 and an insulating layer 619 on which the lower conductor circuit 622 is formed
Get. At the time of this patterning, a laser beam irradiating portion 631 for forming a blind via hole 615 and an exposed portion 632 for forming an electroplating solution circulation hole 611 where the insulating layer 619 is exposed are also formed.

Next, as shown in FIG. 35, the laser light irradiation section 631 of the insulating layer 619 is irradiated with laser light.
A blind via hole 615 is obtained. However, the energy of the laser beam is high at the center and low at the periphery. The lower conductor circuit 622 made of metal reflects laser light. Therefore, the laser beam penetrates the insulating layer 619 in the exposed portion 632, and a hole is formed here. This becomes the plating solution flow hole 611. Note that an excimer laser, a wavelength of 248 nm, and an output of 50 W are used as the laser light.

Next, the insulating layer 619 is immersed in a chemical copper plating bath. Then, the chemical plating solution is circulated through the plating solution circulating hole 611 inside and outside the blind via hole 615. As a result, as shown in FIG. 36, copper is deposited in the blind via hole 615 and the upper conductor circuit 621 and the lower conductor circuit 622, and
A chemical plating layer 617 made of copper is obtained.

Next, as shown in FIG.
19 is immersed in an electroplating bath filled with an electrolytic copper plating solution. Then, the electroplating is performed while flowing the electroplating solution as in the case of the chemical plating. As a result, copper is deposited on the surface of the chemical plating layer 617, and a via plating layer 616 made of copper is obtained. Thus, the printed wiring board 601 according to this example is obtained.

Next, the function and effect of this embodiment will be described. In the printed wiring board according to the present embodiment, a plating solution flow hole 611 having a smaller diameter than the blind via hole 615 is provided in the lower conductive circuit 621 forming the bottom of the blind via hole 615.

Thus, when the via plating layer 616 is formed, the plating solution can flow into and out of the blind via hole 615 through the plating solution flow hole 611. Therefore, a uniform via plating layer 616 can be obtained without becoming mottled. For this reason, it is possible to obtain a printed wiring board 601 having excellent electrical continuity between the upper conductor circuit 621 and the lower conductor circuit 622, that is, having excellent connection reliability between the two.

In the printed wiring board 601 of this embodiment, the plating solution flowing holes 611 are closed by the via plating layer 616, but the through holes are not closed with respect to the completed printed wiring board 601. There may be a plating solution circulation hole as it is.

Although the printed wiring board 601 of this embodiment is a single-layer wiring board, an insulating layer 619 is further provided on the surface of the upper conductor circuit 621 and the lower conductor circuit 622 according to this embodiment to form a multilayer board. Can also.

REFERENCE EXAMPLE 8 As shown in FIG.
An upper surface pattern 706 and a lower surface pattern 705 are provided on the upper surface and the lower surface of 9, and are electrically connected to each other by a conduction hole 707.

A method for manufacturing the above printed wiring board will be described. First, an insulating substrate 7 made of glass epoxy resin
Prepare 09. The thickness of the insulating substrate 709 is 100 μm. Next, copper foil is adhered to the upper and lower surfaces of the insulating substrate 709, and this is etched to form the upper surface pattern 706 and the lower surface pattern 705, and the inner wall of the conduction hole 707 during the electroplating process. An electric lead 761 for passing electricity through the device is formed. The upper surface pattern 706 is formed on the periphery except for the portion where the conductor hole is formed. The lower pattern 705 is formed so as to close the conductor hole forming portion of the insulating substrate 709.

Next, the insulating substrate 709 not covered with the upper surface pattern 706 is irradiated with laser light,
The conduction hole 707 is formed. At this time, the conduction hole 70
Holes are drilled until the bottom of 7 reaches the lower surface pattern 705 formed on the lower surface of the insulating substrate 709. Hole 707 for conduction
Has a diameter of 0.1 mm.

Next, a chemical copper plating process is performed on the insulating substrate 709. Chemical copper plating is performed by a general method.
Thus, a thin-film plating film 731 having a thickness of about 1 μm is formed on the inner wall of the conduction hole.

Next, the surface of the insulating substrate 709 is cleaned. Next, electrolytic copper plating is performed on the insulating substrate 709. In the electrolytic copper plating process, the insulating substrate 709 is immersed in an electroplating bath together with the anode. Chemical plating film 731
Is connected to a negative electrode of a power supply through an electric lead 761 to serve as a cathode. The electroplating bath contains copper sulfate, and the bath temperature is set to 60 ° C. In this state, a current having a current density of 1.2 A / dm ² flows through the chemical plating film 731. As a result, copper elutes from the surface of the cathode, and copper is deposited on the surface of the chemical plating film serving as the anode. This electroplating process is performed for 20 minutes.

This electroplating process is repeated twice to form thick film plating 732. Thereby, a total film thickness of 10 μm is formed from the thin film plating 731 and the thick film plating 732.
m of the metal plating film 703 is obtained. Thereafter, the electrical leads 761 are removed. Thus, a printed wiring board is obtained.

With respect to the obtained printed wiring board, the formation state of the metal plating film in the conduction hole was observed with a microscope. As a result, a metal plating film having a uniform thickness was formed on the inner wall of the conduction hole. The thickness of the metal plating film inside the conduction hole was 10 μm, which was the same as the thickness (10 μm) of the metal plating film formed on the surface of the upper pattern and the lower pattern.

Comparative Example In this example, the current passed through the thin film plating in the electroplating process was 1.5 to 2.0 A / dm ² . In this case, even if the electroplating process is performed, the plating metal may not be normally deposited inside the conduction hole. That is, FIG.
As shown in (1), the thickness of the electroplated film 703 was extremely thin, and in some cases, unplated portions 739 were formed. It is considered that this is because hydrogen gas generated by the electrolytic plating reaction accumulates inside the narrow conduction hole 797.

Reference Example 9 A printed wiring board will be described with reference to FIGS. As shown in FIG. 40, the printed wiring board 802 of this example is provided with conductor patterns 851 and 852 provided on the surface of a thin insulating substrate 806 and solder filling that penetrates the insulating substrate 806 and reaches the upper surface of the conductor pattern 851. Hole 8
01. The inside of the solder filling hole 801 is filled with solder 807.

The insulating substrate 806 is made of an epoxy resin 86
2 is impregnated with a fiber 861 made of glass cloth. As shown in FIG. 40 and FIG.
The end 863 of the fiber 861 protrudes from the wall surface 810. As shown in FIG. 40, the end 863 of the fiber 861 is
It cuts into the solder 807.

The insulating substrate 806 is a thin plate having a thickness of 0.1 mm. The diameter of the solder filling hole 801 is 0.3 mm. The printed wiring board 802 of this example is provided with a solder filling hole 80.
Many 1 are provided. Also, the printed wiring board 802
A mounting portion for mounting an electronic component and a terminal for connecting to a mating member are provided on the surface of the device.

Next, a method of manufacturing the printed wiring board will be described. First, as shown in FIG. 41, an insulating substrate 806 is prepared by impregnating a fiber 861 made of glass cloth into an epoxy resin 862. Next, copper foil is adhered to the upper and lower surfaces of the insulating substrate 806, and unnecessary portions are removed by etching to form conductor patterns 852 and 851. At this time, a part of the conductor pattern 851 is covered on the lower surface of the portion for forming the solder filling hole of the insulating substrate, while the upper surface is opened without forming the conductor pattern 852.

Next, a laser beam 804 is applied to the insulating substrate 806 of the solder filling hole forming portion 815 to form a solder filling hole 801 in the insulating substrate 806 as shown in FIG. At this time, as shown in FIGS. 42 and 43, the fiber 861 is projected from the wall surface 810 of the solder filling hole 801 while leaving the end 863 of the fiber 861. Also, the conductor pattern 851 covering one opening 811 of the solder filling hole 801 is left without being drilled.

Next, as shown in FIG. 40, the solder filling hole 801 not covered with the conductor pattern 852 is used.
The paste-like solder 807 is filled into the inside of the solder filling hole 801 from the other opening 812 by a printing method.
Solder 807 and solder filling hole 801 are joined. Thus, a printed wiring board 802 shown in FIG. 40 is obtained.

Next, the operation and effect of this embodiment will be described. In this example, as shown in FIG. 40, the end 863 of the fiber 861 included in the insulating substrate 806 protrudes from the wall surface 810 of the solder filling hole 801. This fiber 8
The end 863 of 61 is cut into the solder 807 filled in the solder filling hole 801. Therefore, the solder 807 is strongly joined to the solder filling hole 801. Therefore, even when the printed wiring board 802 is mechanically affected from the outside, the solder 807 does not fall out of the solder filling hole 801.

Further, since the end 863 of the fiber 861 exposed from the wall surface 810 of the solder filling hole 801 cuts into the inside of the solder 807, the thin-walled insulating substrate 806 and the wall surface 810 of the solder filling hole 801 are soldered. Even if the bonding area with 807 is small, the solder 807 does not fall out of the solder filling hole 801. Therefore, electrical conduction between the conductor patterns 852 and 851 provided on the upper surface and the lower surface of the insulating substrate 806 can be reliably performed by the solder 807 in the solder filling hole 801.

In this example, as shown in FIG. 41, the solder filling hole 801 is formed by irradiating a laser beam 804 to leave the end 863 of the fiber 861 on the wall surface 810 of the solder filling hole 801. ing. Therefore, the fiber 86 is easily attached to the wall surface 810 of the solder filling hole 801.
One end 863 can project.

As shown in FIG. 42, the laser beam 804 can form the solder filling hole 801 only in the insulating substrate 806, and can simplify the manufacturing process. The conductor pattern 851 covering one opening 811 of the solder filling hole 801 can be left as it is. Therefore, before forming the solder filling hole 801, the conductor patterns 851 and 852 can be formed in advance on both the upper and lower surfaces of the insulating substrate.

REFERENCE EXAMPLE 10 As shown in FIG. 44, the printed wiring board of this example is such that solder 807 is filled in a solder filling hole 801 and then a solder ball 871 is joined to the upper end thereof. The upper part 872 of the solder ball 871 is a part to be joined to the counterpart member 8.

The solder balls 871 are inserted into the solder filling holes 801.
45, the lower portion 873 of the solder ball 871 is formed as a flat surface, and the upper portion 872 of the solder ball 871 is formed in a spherical shape, as shown in FIG.
Next, the solder ball 871 is placed on the solder 807 filled in the solder filling hole 801 with the lower part 873 of the solder ball 871 facing in the same manner as in Reference Example 9. Next, the solder ball 871 and the solder 807 are heated and melted to join them. Others are the same as in Reference Example 9.

Also in this example, the solder 807 is firmly joined to the solder filling hole 801 as in Reference Example 9, so that the solder ball 871 joined on the solder 807 and the solder filling hole 801 Electrical connection reliability can be secured.

Reference Example 11 As shown in FIGS. 46 and 47, the printed wiring board of this example supplies a spherical solder 870 into a solder filling hole 801 and heats and melts the solder 870 to form a solder filling hole. Hole 8
01 is filled with solder.

That is, as shown in FIG. 47, the solder filling hole 801 is formed using laser light in the same manner as in the ninth embodiment. The diameter of the solder filling hole 801 is 0.3 mm. Next, by rolling a spherical solder ball 870 having a diameter of 0.35 mm on the surface of the insulating substrate 806, the solder ball 870 is supplied into the solder filling hole 801.

Next, the solder ball 870 is heated and melted, and as shown in FIG.
The end 863 of the fiber 861 protruding from 10 is cut into the inside of the solder ball 870. Solder ball 870
The upper part 874 of the upper part 874 is a part to be joined to the partner member 808. Others are the same as in Reference Example 9.

Also in this example, since the end 863 of the fiber 861 protruding from the wall surface 810 of the solder filling hole 801 cuts into the solder ball 870, the bonding strength between the solder filling hole 801 and the solder ball 870 is increased. Is high.

Reference Example 12 FIGS. 48 to 5 show a printed wiring board and a method of manufacturing the same.
5 will be described. The printed wiring board 901 of this example is
As shown in FIGS. 52 and 53, two insulating layers 918 and 9 are provided.
19. An inner conductor circuit 921 is provided between the insulating layers 918 and 919. Outermost surface 9 of insulating layer 918
20, a blind via hole 904 is formed toward the inner conductor circuit 921. Blind beer hall 9
04 is filled with solder 912. The cross-sectional shape of the wall surface 940 of the blind via hole 904 is wavy.

The details of the printed wiring board 901 will be described below. As shown in FIG. 52, an outer conductor circuit 931 is provided on the outermost surface 920 of the insulating layer 918. Solder 91
2 are filled with the outer conductor circuit 931 and the inner conductor circuit 92 existing at the bottom 942.
1 is formed so as to ensure electrical continuity between them.

As shown in FIG. 53, the solder 912 filled in the blind via hole 904
, Another electronic component 915 is mounted. In addition,
Although the solder 912 and the solder ball 913 filled in the blind via hole 904 are given different reference numerals for convenience, they are integrated.

Next, a method of manufacturing the printed wiring board 901 will be described. First, a copper-clad laminate having a copper foil on its surface is prepared, and the copper foil is patterned. Next, the surface of the copper foil is subjected to electroless copper plating to obtain an insulating layer 919, an inner conductor circuit 921, and an outer conductor circuit 931.

Next, a prepreg and a copper foil are laminated on the surface of the insulating layer 919. Next, the copper foil is patterned.
Thereafter, electroless copper plating is performed on the copper foil to form an insulating layer 91.
8 and an outer conductor circuit 931 are formed. At this time, a laser beam irradiation part 981 in which the insulating layer 918 is exposed on the outermost surface 920 is also formed at the same time. As the prepreg, a glass cloth impregnated with an epoxy resin is used.

Next, as shown in FIG. 48, the laser light irradiating section 981 is irradiated with laser light using a laser light oscillator 980. Thereby, the insulating layer 918 is vaporized and removed, and a blind via hole 904 reaching the inner layer conductor circuit 921 is obtained.

By the way, the glass cloth portion of the insulating layer 918 is more difficult to vaporize and remove than the epoxy resin portion.
Therefore, as shown in FIG. 49, the wall surface 940 has a wavy shape. That is, the portion protruding from the blind via hole 904 is a portion where the glass cloth exists, and the portion dented with respect to the blind via hole 904 is a portion where the epoxy resin mainly exists. Excimer laser light, a wavelength of 248 nm, and an output of 50 W were used as the laser light.

Next, as shown in FIG. 49, molten solder is poured into the blind via hole 904. As a result, as shown in FIG.
Is filled with solder 912. Next, as shown in FIG. 51, a solder ball 913 is placed on the surface of the solder 912, and FIG.
As shown in FIG. 2, heat fusion is performed on the solder 912. afterwards,
As shown in FIG. 53, the electronic component 915 is bonded on the solder ball 913. Thus, the printed wiring board 901 according to this example is obtained.

Next, the function and effect of this embodiment will be described. In the printed wiring board 901, as shown in FIG. 53, the cross-sectional shape of the wall surface 940 of the blind via hole 904 is uneven (corrugated). For this reason, the solder 912 filled in the blind via hole 904 cuts into the unevenness and is fixed to this portion. Therefore,
The solder 912 can obtain high adhesion strength to the blind via hole 904.

In the printed wiring board 901 of this embodiment, the insulating layer 918 is made of a prepreg in which glass cloth is impregnated with an epoxy resin, so that the blind via hole 904 having a wavy cross section only by irradiating a laser beam. Can be obtained. Further, since the holes are drilled by the laser beam, the blind via hole 904 can have a small diameter of 100 μm.

As another example of the shape of the blind via hole 904 according to the present example, as shown in FIG.
A concave shape that spreads in the lateral direction of the blind via hole 904,
As shown in FIG. 55, a convex shape protruding inward of the blind via hole 904 can be given.

Reference Example 13 A method of manufacturing a printed wiring board will be described with reference to FIGS. An outline of the manufacturing method of this example will be described. First, as shown in FIG. 56, in step S1, a conductor pattern is formed on an insulating substrate. Next, in a step S2, a heat radiating plate is bonded to the insulating substrate on the lower surface of the mounting substrate on the insulating substrate. Next, in a step S3, the mounting concave portion is opened by irradiating a laser beam from the upper surface side of the mounting concave portion forming portion.

Next, the details of the above manufacturing method will be described. First, in step S1, an insulating substrate made of a glass epoxy resin substrate is prepared. The thickness of the insulating substrate is 0.
3 mm. Next, a copper foil is attached to one surface of the insulating substrate, and an exposure method, etching, and the like are performed. Thereby, as shown in FIG. 57, the conductor pattern 7 is formed from the copper foil. Next, Ni / Au is applied to the surface of the conductor pattern 7.
Cover the plating film. Next, the surface of the insulating substrate 5 is covered with a solder resist 59. At this time, an opening for exposing the bonding pad 71 in the conductor pattern 7 is formed in the solder resist 51.

The heat sink 6 is bonded to the lower surface of the mounting recessed portion 10 of the insulating substrate 5. The radiator plate 6
It is a copper plate having a thickness of 0.2 mm.

Next, as shown in FIG. 57, the laser beam 2 is irradiated from the upper surface side of the mounting concave portion forming portion 10. As the laser beam 2, a carbon dioxide laser is used. The irradiation of the laser beam is stopped when the bottom of the mounting recess 1 reaches the surface of the heat sink 6. Thus, as shown in FIG. 58, the mounting substrate 1 is formed by making a hole in the insulating substrate 5. Thus, the printed wiring board 3 is obtained.

As shown in FIG. 59, the printed wiring board 3 has an adhesive 4 such as a silver paste on the bottom of the mounting recess 1.
1 is used to mount the electronic component 4. The electronic component 4 is connected to the bonding pad 71 via the bonding wire 44.
Is electrically connected to the conductor pattern 7.

Next, the operation and effect of this embodiment will be described. As shown in FIG. 56, after the mounting recess forming portion of the insulating substrate is covered with a heat sink, the mounting recess is opened by irradiating a laser beam. Therefore, an opening having a desired size can be easily obtained.

Further, in this example, as shown in FIG. 57, the mounting concave portion 1 is opened by irradiating the upper surface of the mounting concave portion forming portion 10 with laser light 2. At this time, the laser light 2 vaporizes and removes the insulating substrate 5 by its high energy, and sequentially drills holes inside the insulating substrate 5. Then, when the tip of the laser beam 2 reaches the radiator plate 6, the laser beam 2 is reflected by the metal radiator plate 6. Therefore, the irradiation of the laser beam 2 is stopped here. Thereby, the non-penetrating mounting concave portion 1 in which one opening is covered with the heat radiating plate 6 can be formed.

Further, since the mounting concave portion 1 is formed by irradiating the laser beam 2, the hole can be formed without damaging the insulating substrate 5. Further, as shown in FIG. 59, the bottom of the mounting recess 1 is the surface of the heat sink 6. Therefore, the electronic component 4 is mounted on the surface of the heat sink 6 inside the mounting concave portion 1. Therefore, the mounting concave portion 1 having excellent heat dissipation can be formed.

REFERENCE EXAMPLE 14 As shown in FIG. 60, the printed wiring board of this example has a multilayer substrate 50 in which two insulating substrates 51 and 52 are laminated. A conductor pattern 72 is formed between the insulating substrates 51 and 52. The conductor pattern 72 provided inside the multilayer substrate 50 is electrically connected to the conductor patterns 7 and 76 provided on the surface of the multilayer substrate 50 via through holes 73.

In manufacturing the printed wiring board 31, first, two flexible films having a thickness of 0.2 mm and having flexibility are prepared. These are insulated substrate 5
1, 52. Next, conductor patterns 7, 72, 76 are formed on the surfaces of the insulating substrates 51, 52, and these are adhered with a resinous adhesive to obtain a multilayer substrate 50.

Next, a through hole 73 is formed in the multilayer substrate 50 using a drill, and the inner wall thereof is coated with a copper plating film 74. Next, the surface of the multilayer substrate 50 is removed except for the periphery of the through-hole 73 and the mounting recessed portion.
Cover with solder resist 59. Thereafter, as in the case of the above-described reference example 13, the mounting recess 1 is irradiated with laser light.
Is formed to obtain the printed wiring board 31. Others are the same as in Reference Example 13.

In this example, the conductor pattern 72 is formed not only on the surface of the multilayer substrate 50 but also inside it. Therefore, high-density wiring of the printed wiring board 31 can be realized. In addition, by laser light irradiation,
The mounting recess 1 penetrating through the insulating substrates 51 and 52 is formed. Therefore, there is no need to previously form through holes for each insulating substrate as in the related art, and it is not necessary to perform positioning for connecting these through holes. Therefore, according to the manufacturing method of this example, the printed wiring board 31 can be easily manufactured. In addition, in this example,
The same effect as in Reference Example 13 can be obtained.

[0303]

According to the present invention, it is possible to form a via hole having reliable conductivity without causing damage to the inner conductor circuit by laser light, and to realize a new circuit by laser light. A method for manufacturing a wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a lamination process of a printed wiring board in Reference Example 1.

FIG. 2 is an explanatory view of forming a blind via hole by laser light in Reference Example 1.

FIG. 3 is an enlarged explanatory view of a first insulating layer in Reference Example 1.

FIG. 4 is a bottom view of an inner conductor circuit having an opening hole in Reference Example 1.

FIG. 5 is a cross-sectional view of a printed wiring board in which a blind via hole is formed by punching in Reference Example 1.

FIG. 6 is a cross-sectional view of a printed wiring board in which a metal plating film is formed in a blind via hole in Reference Example 1.

FIG. 7 is an explanatory diagram of laser beam irradiation in Reference Example 1.

FIG. 8 is a cross-sectional view taken along the line YY of FIG. 9, showing the formation of a blind via hole by laser light in Reference Example 2.

FIG. 9 is an explanatory plan view of a printed wiring board in which a blind via hole is formed in Reference Example 2.

FIG. 10 is an explanatory diagram of a printed wiring board in Reference Example 2.

FIG. 11 is an explanatory view showing a copper-clad laminate serving as an inner layer board in the method for manufacturing a printed wiring board according to Reference Example 3;

FIG. 12 is an explanatory view showing the formation of through holes in the method for manufacturing a printed wiring board, following FIG. 11;

FIG. 13 is an explanatory view following FIG. 12 but showing formation of an inner-layer conductor circuit in the method of manufacturing a printed wiring board;

FIG. 14 is an explanatory view showing the formation of a blackened film and an exposed portion in the method for manufacturing a printed wiring board, following FIG. 13;

FIG. 15 is an explanatory view showing the lamination of the prepreg and the copper foil in the method for manufacturing a printed wiring board, following FIG. 14;

FIG. 16 is an explanatory view following FIG. 15 and showing formation of an insulating layer in the method of manufacturing a printed wiring board;

FIG. 17 is an explanatory view showing the patterning of the copper foil in the method of manufacturing a printed wiring board, following FIG. 16;

FIG. 18 is an explanatory view showing the formation of the second conductor circuit in the method for manufacturing a printed wiring board, following FIG. 17;

FIG. 19 is an explanatory view following FIG. 18 showing the formation of another pair of insulating layers and the second conductor circuit in the method for manufacturing a printed wiring board;

FIG. 20 is an illustrative sectional view of a printed wiring board according to Reference Example 3;

FIG. 21 is an explanatory view showing a mask provided on the surface of an inner conductor circuit according to Reference Example 3;

FIG. 22 is an explanatory view showing a blackened film formed on the surface of the inner conductor circuit according to Reference Example 3.

FIG. 23 is an explanatory view of a copper foil pattern serving as a second conductor circuit and an exposed portion according to Reference Example 3;

FIG. 24 is an explanatory diagram showing formation of a via hole by laser light irradiation according to Reference Example 3.

FIG. 25 is an explanatory diagram of via hole formation by laser light irradiation according to Reference Example 4.

FIG. 26 is an explanatory diagram of formation of a copper foil pattern using plating on an insulating layer according to Reference Example 4.

FIG. 27 is an explanatory sectional view of a printed wiring board in Reference Example 5;

FIG. 28 is a sectional view taken along the line AA of FIG. 27;

FIG. 29 is an explanatory diagram of via hole formation by laser light irradiation in Reference Example 5.

FIG. 30 is an explanatory sectional view of a printed wiring board according to Reference Example 6;

FIG. 31 is an illustrative sectional view of a printed wiring board according to the first embodiment;

FIG. 32 is a sectional view taken along the line AA in FIG. 31;

FIG. 33 is an explanatory sectional view of a via hole according to the second embodiment;

FIG. 34 is an explanatory sectional view showing a copper-clad laminate according to Reference Example 7;

FIG. 35 is an explanatory sectional view showing perforation of a blind via hole by laser light according to Reference Example 7;

FIG. 36 is an explanatory sectional view showing formation of a chemical plating layer for a blind via hole according to Reference Example 7;

FIG. 37 is an illustrative sectional view of a printed wiring board according to Reference Example 7;

FIG. 38 is a sectional view of a printed wiring board according to Reference Example 8;

FIG. 39 is a sectional view of a printed wiring board of a comparative example.

FIG. 40 is a sectional view of a printed wiring board in Reference Example 9;

FIG. 41 is a cross-sectional view of an insulating substrate, showing a method for forming a solder filling hole in Reference Example 9;

FIG. 42 is a sectional view of an insulating substrate in which solder filling holes are formed in Reference Example 9.

FIG. 43 is a cutaway perspective view of a printed wiring board showing a state of a wall surface of a hole for filling solder in Reference Example 9;

FIG. 44 is a sectional view of a printed wiring board in Reference Example 10.

FIG. 45 is an explanatory view showing a method of joining a solder ball to solder filled in a solder filling hole in Reference Example 10.

FIG. 46 is a sectional view of a printed wiring board in Reference Example 11;

FIG. 47 is an explanatory view showing a method of supplying a solder ball into a solder filling hole in Reference Example 11;

FIG. 48 is an explanatory view showing laser light irradiation in manufacturing a printed wiring board according to Reference Example 12.

FIG. 49 is an explanatory view showing a blind via hole in manufacturing a printed wiring board according to Reference Example 12;

FIG. 50 is an explanatory view showing a blind via hole filled with solder in manufacturing a printed wiring board according to Reference Example 12;

FIG. 51 is an explanatory view showing installation of solder balls in manufacturing a printed wiring board according to Reference Example 12;

FIG. 52 is an explanatory view showing a cross section of a main part of a printed wiring board according to Reference Example 12;

FIG. 53 is an explanatory view showing a printed wiring board and other electronic components installed thereon according to Reference Example 12;

FIG. 54 is an explanatory cross-sectional view of a main part of a printed wiring board having a concave blind via hole according to Reference Example 12;

FIG. 55 is an explanatory cross-sectional view of a principal part of a printed wiring board having a blind blind via hole of a convex shape according to Reference Example 12;

FIG. 56 is a process explanatory view of the method for manufacturing a printed wiring board of Reference Example 13;

FIG. 57 is a cross-sectional view of a printed wiring board for illustrating a method of forming a mounting recess in Reference Example 13.

FIG. 58 is a sectional view of a printed wiring board according to Reference Example 13;

FIG. 59 is a cross-sectional view of a printed wiring board on which electronic components are mounted in Reference Example 13.

FIG. 60 is a sectional view of a printed wiring board according to Reference Example 14;

FIG. 61 is an explanatory view of a printed wiring board in a conventional example.

FIG. 62 is an explanatory view of drilling by laser light in a conventional example.

FIG. 63 is an explanatory view for explaining a problem of drilling by laser light in a conventional example.

[Explanation of symbols]

101. . . First insulating layer, 151, 154. . . Laser light irradiation hole, 102. . . Second insulating layer, 103. . . Third insulating layer, 131, 161. . . Inner layer conductor circuit, 133, 153, 155. . . Outer conductor circuit, 160. . . Opening holes, 151,154. . . Laser light irradiation holes, 141, 142. . . Blind via hole, 171. . . Surplus holes, 175, 176. . . Metal plating film, 108. . . Laser light oscillator, 181. . . Laser light, 210. . . Printed wiring board, 211, 212, 213. . . Insulating layer, 221-225. . . Inner layer conductor circuit, 3A, 3C. . . Reference holes, 3B, 3D, 3E. . . 241. Blind via hole with large depth, 241. . . Laser light oscillator, 242. . . Reference laser beam, 245. . . 296. Coordinate control device . . Metal plating film, 301. . . Printed wiring board, 303, 330. . . Via hole, 304. . . Inner layer conductor circuit, 305. . . Solder, 306, 360. . . Second conductor circuit, 315. . . Through hole, 319. . . Inner layer plate, 328, 329. . . Insulating layer, 340. . . Blackened film, 341,361. . . Copper foil pattern, 342, 362. . . Metal plating film, 345. . . Membrane, 346. . . Mask, 349, 369. . . Exposed, 381. . . Solder ball, 382. . . Solder resist, 401, 408. . . Printed wiring board, 402, 403, 426. . . Via hole, 404, 449. . . Annular intermediate land, 405. . . Internal metal plating film, 417. . . Boundary part, 413, 414, 415, 416, 418. . . Insulating layer, 419. . . Inner layer plate, 420. . . Inner wall surface, 425,435. . . Opening edge, 440, 447. . . Opening holes, 441, 448. . . Exposed part, 450. . . Step-shaped plating film, 452. . . Steps, 453, 457. . . External via hole, 454, 459. . . Internal via hole, 458. . . Intermediate via hole, 461. . . Inner layer conductor circuit, 462. . . Outer layer conductor circuit, 463, 464, 465. . . Boundary conductor circuit, 501, 508. . . Printed wiring board, 502, 529, 503. . . Via hole, 504. . . Annular dummy land, 511-516, 518. . . Insulating layer, 517. . . Boundary part, 520, 530. . . Inner wall surface, 525,535. . . Rim of opening, 521. . . Internal metal plating film, 528. . . Through hole, 540. . . Opening hole, 561. . . Outer layer conductor circuit, 562, 563, 564. . . Inner layer conductor circuit, 601. . . Printed wiring board, 611. . . Hole for plating solution, 615. . . Blind via hole, 616. . . Via plating layer, 617. . . Chemical plating layer, 619. . . Insulating layer, 621. . . Upper conductor circuit, 622. . . Lower conductor circuit, 631. . . Laser beam irradiation part, 632. . . Exposed part, 703. . . Metal plating film, 705. . . Top pattern, 706. . . Lower surface pattern, 707. . . Hole for conduction, 709. . . Insulating substrate, 731. . . Thin film plating, 732. . . Thick film plating, 761. . . Electrical leads, 801. . . Hole for solder filling, 802. . . Printed wiring board, 804. . . Laser light, 806. . . Insulating substrate, 807. . . Solder, 808. . . Mate member, 810. . . Wall surface, 851, 852. . . Conductor pattern, 861. . . Fiber, 862. . . Resin, 863. . . End, 870, 871. . . Solder balls, 872,874. . . Upper part, 873. . . Bottom, 901. . . Printed wiring board, 904. . . Blind via hole, 912. . . Solder, 913. . . Solder ball, 915. . . Electronic components, 918, 919. . . Insulating layer, 920. . . Top surface, 921. . . Inner layer conductor circuit, 931. . . Outer layer conductor circuit, 940. . . Wall surface, 941. . . Perimeter, 942. . . Bottom, 981. . . Laser irradiation part, 1. . . 9. mounting recess, . . 1. mounting recess forming portion; . . Laser light, 3,31. . . Printed wiring board, 4. . . Electronic components 41. . . Adhesive, 44. . . Bonding wire, 5,51,52. . . Insulating substrate, 50. . . Multilayer substrate, 59. . . 5. Solder resist, . . Heat sink, 7, 72, 76. . . Conductor pattern, 73. . . Through hole, 74. . . Copper plating film,

 ──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 9-52482 (32) Priority date February 19, 1997 (Feb. 19, 1997) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-52483 (32) Priority date February 19, 1997 (Feb. 19, 1997) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-52484 (32) Priority date February 19, 1997 (February 19, 1997) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-61921 ( 32) Priority date February 27, 1997 (Feb. 27, 1997) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-65511 (32) Priority date 1997 March 3, 1997 (3.3.3) (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-69158 (32) Priority date March 5, 1997 (1997. 3.5) (33) Priority Claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 9-85786 (32) Priority date March 19, 1997 (March 19, 1997) (33) Priority claiming country Japan (JP) (72) Inventor Hiroyuki Kobayashi 3-200 Kawama-cho, Ogaki-shi, Gifu Prefecture Inside the Kawama Plant of IBIDEN Co., Ltd. ) Inventor Yoshikazu Ukai 3-200 Kawamacho, Ogaki-shi, Gifu Pref. In the Kawama Plant of IBIDEN Corporation (72) Inventor Mitsuhiro Kondo 3-200 Kawamacho, Ogaki-shi, Gifu Pref. Reference) 5E346 AA02 AA15 AA35 AA43 BB16 CC04 CC10 CC32 DD02 DD12 DD32 EE33 FF07 FF15 GG15 GG17 GG22 GG28 HH07

Claims (4)

[Claims] 1. A semiconductor device having at least two insulating layers on an inner conductor circuit, and a via hole penetrating from the outermost surface of the insulating layer through the two or more insulating layers to reach the inner conductor circuit, In the printed wiring board provided with an internal metal plating film for electrically connecting the inner conductor circuit and the outer conductor circuit formed on the outermost surface in the via hole, the two or more insulating layers are connected to each other. A printed wiring board characterized in that a reinforcing annular dummy land having an opening around the via hole is provided at the facing boundary portion, and the annular dummy land is joined to the internal metal plating film. . 2. The printed wiring board according to claim 1, wherein the annular dummy land has an outer diameter larger than a diameter of the via hole, and has an opening having the same diameter as the diameter of the via hole. And a via hole extending from the outermost surface of the insulating layer through the at least two insulating layers to reach the inner-layer conductive circuit; and The via hole is provided with an internal metal plating film for electrically connecting the inner conductor circuit and the outer conductor circuit formed on the outermost surface, and the two or more insulating layers face each other. At the boundary portion, a reinforcing annular dummy land having an opening around the via hole is provided, and the annular dummy land is provided in the method for manufacturing a printed wiring board joined to the internal metal plating film. The via hole is formed by irradiating a laser beam from the outermost surface toward the inner conductor circuit,
At this time, a method of manufacturing a printed wiring board, characterized in that the laser light penetrates through the opening of the annular dummy land to reach the inner conductor circuit, and then forms the inner metal plating film. 4. The printed wiring board according to claim 3, wherein the annular dummy land has an outer diameter larger than the diameter of the via hole, and has an opening having the same diameter as the diameter of the via hole. Production method.