JPH11195864A - Manufacture of wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high precision board through a simple fining method by plating a metal which allows etching resist on a part of a conductor layer upper surface for forming a connection pad, and, with it as an etching resist, chemically roughening a conductor layer upper surface around a pad not covered with the connection pad. SOLUTION: The entire upper surface of a conductor layer 2 is physically roughened to remove an oxide film (b), then a plating resist 25 coats the upper surface of the conductor layer 2 except for a connection pad arranging part 2a (c). Then on the upper surface of the pad arranging part 2a, a metal is plated to form a plating layer 5, provided with a pad 4. Here, the upper surface of the conductor layer 2 coated with a plating layer is less rough, so the upper surface of the pad 4 is sufficiently flattened even with thinner plating (d). After the resist 25 is removed (e), the surface where the resist 25 is removed is made more rough than the surface of the pad arranging part 2a using the pad 4 as an etching resist (f). Thus, form and size of a pad are accurately and finely set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board suitable for mounting electronic components such as various chip elements including semiconductor chips in a cavity and mounting them.

[0002]

2. Description of the Related Art As electronic devices have become lighter and thinner, semiconductors, SAW elements, sensor elements, and the like, as well as resistors, coils, capacitors, and the like have been made into chips.
2. Description of the Related Art Surface mounting technology for directly mounting a chip element on a surface of a wiring board such as a structure is widely used.

[0003] Hereinafter, a conventional wiring board that can be surface-mounted will be described. FIG. 6 is a cross-sectional view showing a structure of a conventional wiring board provided with connection pads for fixing chip elements on the upper surface. A conductor layer 2 formed by a copper foil and a copper plating layer adhered on the copper foil is laminated on the upper surface of a base material 101 made of an epoxy resin or a BT resin.
A connection pad (hereinafter, may be simply referred to as a pad) 104 for bonding and mounting a chip element is provided on a part of the upper surface of the device 2. The oxide film is removed on the entire upper surface of the conductor layer 102 including the upper surface of the conductor layer 102 that is the base of the pad 104, and a resin layer (hereinafter, sometimes referred to as a prepreg) 106 such as a prepreg or a resist is also formed. Is roughened by a scrubber or the like to a surface roughness of about 0.3 to 0.5 μm in order to facilitate adhesion to the upper surface of the conductor layer 102 by an anchor effect. In the illustrated example, the cover layer 107 made of BT resin is laminated and adhered to the upper surface of the conductor layer 2 by the prepreg 106. This step of roughening the surface with a scrubber or the like and adhering the cover layer 107 as an adherend with a prepreg is similar to a conventionally used multilayer wiring board.

The pad 4 has, for example, a nickel layer having a thickness of about 5 μm on the conductor layer 2, and a nickel layer having a thickness of 0.
The pad is formed of a multi-layered plating layer provided with a gold layer of about 5 μm. By forming the pad with such a multi-layered thick plating layer, the surface of the pad is flattened, and the bumps 108 of the chip element 103 are formed by ultrasonic waves. Reliability when bonding with solder or solder.

However, in order to further reduce the size and weight of electronic devices, for example, a wiring board capable of bonding and laminating with high precision in units of microns is required. It is important that the area occupied by the bumps on the wiring board can be minimized so that the wiring board can be downsized.

[0006] In response to these demands, according to the above-described prior art, there is a problem that the distance between the chip element and the resin layer cannot be reduced to a necessary minimum. When a structure such as a cover layer is laminated and bonded on a wiring board, an adhesive resin such as a prepreg or an adhesive flows out to the upper surface of the pad by softening by heating and pressing for adhesion. FIG. 7 is a cross-sectional view of a main part showing a state in which the prepreg is softened by heating during bonding and flows out to the upper surface of the pad. The resin spreads easily on the upper surface of the clean and flat pad, and it is difficult to find even if it spreads on the pad because many of the highly fluid components 106a contained in the resin are transparent. Moreover, the resin film cured on the pad significantly impairs the bonding property. Alternatively, the resin may be applied to the bumps of the chip element or the chip element itself, which may hinder its function. For this reason, according to the prior art, in general, in order to realize a reliable bonding to the pad, a margin for inflow of resin must be provided while ensuring safety, which is more than necessary than the size of the chip element. Had to have a wide pad. As a result, the size of the wiring board has been increased. In addition. Even when the pad is small, the periphery thereof, that is, the interval between the outer periphery of the pad and the inner periphery of the resin layer, is designed so that components flowing out of the resin layer do not reach the bumps of the chip element or the chip element itself. It has to be sufficiently wide, and as a result, it is difficult to further reduce the size of the wiring board.

[0007] Accordingly, the present applicant has filed another patent application, which discloses a conductor layer provided on a base material and a connection pad arranged on a connection pad arrangement portion provided on a part of the surface of the conductor layer. Wherein a resin inflow prevention portion is provided adjacent to the connection pad arrangement portion of the conductor layer, and the surface roughness of the resin inflow prevention portion is larger than the surface roughness of the connection pad arrangement portion. Proposed a wiring board. It is preferable that the connection pad arrangement portion is physically roughened, and the resin inflow prevention portion is chemically roughened.

According to this wiring board, the interval between the resin layer and the chip element or the like connected on the connection pad can be made narrower than before by providing the above-mentioned resin inflow prevention portion. The size can be reduced.

When such a wiring board is formed by a conventional method, it is considered that the wiring board is formed by the following steps.

Referring to FIG. 8, a conductor layer 10 on a substrate 101 is formed.
2 is physically roughened by a scrubber or the like (a), and thereafter, the connection pad arrangement portion 102a is covered with an etching resist 110 (b), and then a conductor layer not covered with the etching resist is formed. Is etched and roughened (c). After removing the etching resist (d), a plating resist 112 is applied to cover the upper surface of the roughened conductor layer (e), and the upper surface of the conductor layer that is not covered with the plating resist, that is, the connection pad arrangement portion 102a Then, a connection layer 104 is formed by depositing a plating layer (f). Thereafter, the plating resist is removed to complete the operation (g).

[0011]

However, according to the above technique, the following problems remain unsolved. According to the method using a plating resist after using an etching resist, two photolithography steps have to be performed. For this reason, conventionally, a useless space has to be provided by a tolerance for mask alignment.
As a result, the plating area required for the pad is larger than the area that is essentially required for bonding, and the pad is large. That is, considering the masking deviation due to the plating resist as shown in FIG. 8E and thereafter, the necessary pad width W as shown in FIG.
In order to secure 1 securely, it is necessary to increase the width to the width W2.

That is, according to the above technique, there is a problem that it is impossible to provide a fine and highly accurate wiring board.

Therefore, the present invention provides a simplified process,
It is an object of the present invention to provide a method for manufacturing a wiring board capable of manufacturing a fine and highly accurate wiring board.

[0014]

The above object is achieved by the present invention described below. (1) In a method of manufacturing a wiring board provided with a connection pad formed of a plating layer on a part of a conductor layer on a base material, when the conductor layer is chemically roughened, an etching resist and Forming a connection pad by metal-plating a part of the upper surface of the conductor layer so as to form at least an uppermost portion of the connection pad with the metal; Is used as an etching resist to chemically roughen the upper surface of the conductor layer not covered by the connection pad to form a rougher upper surface on the conductor layer around the pad than the upper surface of the conductor layer covered by the connection pad. A method for manufacturing a wiring board, comprising: (2) In the method for manufacturing a wiring board in which a connection pad formed on a part of a conductor layer on a base material by a plating layer and a coating layer is provided around the connection pad on the conductor layer, When chemically roughening, by means of chemically roughening the coating layer, a metal that is not roughened is selected, and the metal is used to form at least the uppermost portion of the connection pad. A pad forming step of forming a connection pad by metal plating a part of the upper surface of the conductor layer; and chemically roughening the upper surface of the cover layer to be rougher than the upper surface of the conductor layer covered by the connection pad. A step of forming a rough upper surface on a coating layer around the pad by a chemical roughening step. (3) The method of manufacturing a wiring board according to (1) or (2), wherein the conductor layer is formed of copper, and a metal forming at least an uppermost portion of the connection pad is gold.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a wiring board according to the present invention will be described below with reference to the accompanying drawings. Prior to describing the method for manufacturing the wiring board of the present invention, an example of a wiring board manufactured by the method of the present invention will be described.

FIG. 4 is a sectional view showing an example of the structure of a wiring board manufactured by the manufacturing method of the present invention. The conductor layer 2 is laminated on the upper surface of the substrate 1. Base material 1
Is preferably formed of, for example, an epoxy resin or a BT resin as described above, and has a thickness of about 0.1 to 1.6 mm. Furthermore, 0.2-0.8 mm, especially 0.3
~ 0.5 is preferred. The conductor layer 2 is preferably formed of copper or the like. Conventionally, as shown in FIG. 5, a copper plating layer 2 is formed on a copper foil 2-1.
The copper foil 2-1 has a thickness of 9 to 35 μm, particularly 12 to 18 μm.
m, and the thickness of the copper plating layer 2-2 is 3 to 25 μm.
In particular, it is preferably about 5 to 20 μm. This copper plating layer has a function of flattening the surface.

On a predetermined part of the upper surface of the conductor layer 2, a connection pad arrangement part 2a is provided. A connection pad 4 (hereinafter, may be simply referred to as a pad) for mounting and connecting an electronic component or the like, for example, a chip element, is provided on the connection pad arrangement portion 2a of the conductor layer. This pad 4
Is usually composed of two or more plating layers, for example, a nickel plating layer as a base layer and a gold plating layer as a surface layer formed thereon. The pad 4 preferably has a thickness of 5 to 10 μm, a surface layer of 0.5 to 3 μm, and a total thickness of about 5.5 to 13 μm. In addition to the above, the pad 4 may be formed by solder plating (solder leveler), tin plating, silver plating, or the like, and is selected by means for connecting to a chip element or the like. The size (area) of the connection pad arrangement portion 2a, that is, the pad 4 depends on the size of the electronic component, but may be about 90 to 130% larger than that of the electronic component.

The connection pad arrangement section 2a mainly includes
In many cases, it is composed of a plating layer as described above. In order to facilitate the formation of the pad, it is preferable that a surface roughening treatment or the like is performed for the purpose of removing the oxide film formed on the surface. The surface roughness of the connection pad arrangement portion 2a is:
It is preferably about 0.3 to 0.5. In this specification, the conductor layer does not include the pad.

A resin flow preventing portion 2b having a predetermined width is provided in a peripheral portion of the conductor layer 2 adjacent to the connection pad disposing portion 2a substantially continuously and substantially flush. The width of the resin inflow prevention portion 2b is preferably about 0.1 to 0.5 mm. The surface of the resin inflow prevention portion 2b is roughened with a roughness greater than the surface roughness of the electronic component connection pad arrangement portion 2a.

On the outer side of the resin inflow prevention portion 2b of the conductor layer 2, a resin layer 2 such as a prepreg is
A resin layer forming portion 2c for forming 0 is provided. The resin layer forming portion 2c is formed of the resin inflow preventing portion 2
Preferably, it has the same surface roughness as b, but not necessarily.

A resistor, coil, capacitor, semiconductor, SA,
Chip elements 10 such as W and sensors are connected and mounted by bonding via the bumps 11. The effect of the wiring board of the present invention is particularly remarkable when the chip element 10 is a SAW element. That is, since the SAW element uses the surface acoustic wave characteristics of the piezoelectric material, if the prepreg or the like touches the SAW element, the element characteristics are greatly impaired.
According to the present invention, even when the lid is sealed with the prepreg, the outflow of the prepreg is stopped by the rough surface of the resin inflow prevention portion, and the prepreg does not flow on the pad. The outer shape of the container that houses the SAW element can be reduced in size, and a highly reliable SAW device can be provided.

The above pad can be used as a pad for wire bonding. The bonding is usually performed by ultrasonic bonding, a conductive adhesive, solder, or the like.

A portion around the mounting object 30 such as a cover layer or a lid is adhered to the resin layer forming portion 2c of the conductor layer 2 via, for example, a prepreg 20 which is a resin layer. The electronic component is sealed in the space inside 30. In this case, the prepreg 20 is formed in the resin layer forming portion 2c.
It becomes a resin layer formed thereon.

In the sealing step using the prepreg 20, the prepreg 20 is heated. At this time, the highly fluid component 20a flowing out of the prepreg 20 is stored in the resin inflow preventing portion 2b, and the pad 4 is heated. Flowing into the part is prevented. Examples of the resin layer include, in addition to the prepreg, an adhesive, a resist agent, a surface protective agent, a heat conductive paste or ink, or a conductive resin. While the molecular weight resin, solvent component, and vehicle component have the property of spreading on a flat plating surface with fluidity, the rough surface that impedes the fluidity is arranged around the pad, so that the plating layer The purpose of the present invention is to prevent the spread of these fluid components on the upper surface of the pad, which is not limited to the example described in this specification, and can be applied in various ways.

Although not shown, a coating layer such as a plating resist is provided on a surface of the base material other than the pad portion on the upper surface of the conductor layer, and the upper surface of the coating layer is used as a resin flow preventing portion of the conductor layer. By similarly roughening, the covering layer can have the same function as the above-described roughened conductor layer. According to this modification, for example, the upper surface of the plating resist, which is a coating layer, may be formed as a rough surface, and the attachment 30 such as a cover layer may be laminated and adhered on the plating resist with the prepreg 20 interposed therebetween. According to this modification, after the resist is applied and the plating for the pad is performed, the surface of the plating resist can be chemically roughened without attacking the pad with an alkaline solution or the like. In this method, a resin layer such as a plating resist is used as a permanent resist, so that the manufacturing process of the wiring board can be simplified. In addition, since the uneven portion of the wiring board is filled with the permanent resist, flatness can be ensured.

FIG. 1 is an explanatory view illustrating a method of manufacturing a wiring board according to the present invention. The upper surface of the conductor layer 2 such as a copper foil laminated on the base material 1 is formed as a flat surface by performing a copper plating or the like after forming a through hole as necessary. A wiring pattern having a desired shape is formed on the conductor layer 2 by a tenting method or the like.
(A)).

The entire upper surface of the conductor layer 2 on the substrate 1 is physically roughened, preferably by a scrubber or the like (b). In the present invention, the surface roughening may be such that the oxide film on the conductor layer is removed, and preferably, the surface roughness of the roughened upper surface of the conductor layer 2 is 0.3 to 0.1 mm. 5μ
m is preferable. The conventional surface roughening not only removes the oxide film on the conductor layer but also increases the surface roughening for the purpose of obtaining an anchor effect in the case of bonding the prepreg or the like as described above. However, in the present invention, since the surface roughening for exhibiting the anchor effect for the prepreg or the like is performed again later, only the oxide film may be removed, and thus the surface roughening is performed as described above. Can be smaller. In this sense, this step may be performed by any means as long as the oxide film can be removed.

A plating resist 25 is applied to the upper surface of the conductor layer 2 except for the connection pad arrangement portion 2a which is a region for forming a pad (see FIG. 1C). The plating resist is a dry film or a liquid photosensitive resin, and by exposure and development, the plating resist is left in portions where plating is unnecessary.

Then, a metal such as copper, nickel, or gold is sequentially plated on the upper surface of the connection pad disposing portion 2a of the conductor layer 2 which is not covered with the plating resist 25, as needed, to form the pad 4. 5 are formed. At this time, since the upper surface of the conductor layer 2 on which the plating layer is deposited has a small surface roughness as described above, the upper surface of the pad is sufficiently flat even if the thickness of the plating layer is reduced as compared with the prior art. (See FIG. 1D).

After that, the plating resist 25 is removed with, for example, an alkaline solution (see FIG. 1E), and the pad 4 is used as an etching resist, and the upper surface of the conductor layer 2 in the wiring pattern region where the plating resist is removed (ie, the resin). The inflow preventing portion 2b and the upper surface of the resin layer forming portion 2c) are roughened more than the surface roughness of the connection pad placement portion 2a (see FIG. 1F). The surface roughness is
Specifically, it is preferably 0.5 to 10 μm, particularly preferably 1 to 5 μm. If the thickness is less than 0.5 μm, the effect of preventing the resin from flowing in is not sufficient, and if the surface is excessively roughened, not only processing (especially chemical processing) becomes difficult, but also a through hole formed in the wiring board. This is because the end face (edge) may be cut.

The above surface roughness was determined by the following experiment. The surface of the sample having a surface equivalent to the surface of the conductor layer 2 is referred to as MECetchB manufactured by Mec Co., Ltd.
Surface roughness 0.5, 1, using OND CZ-8100
2, 3, 4 and 5 μm. The prepregs were adhered by heating to these samples, and the amount of run-off in each sample was measured. Specifically, as the prepreg, 60
μm BT resin, heating at 200 ° C. for 2 hours
A pressure of kg / cm ² was applied, and how the outflow of the prepreg changed depending on the degree of roughening of the sample surface was measured. The results are shown in the graph of FIG. In addition, the solid line in the figure indicates the average value of the outflow amount, and the broken line indicates the upper limit (average value + 3σ) of the outflow amount of 3σ. As can be seen from the graph of FIG. 2, the amount of the prepreg flowing out is 0.17 mm or less on average by setting the surface roughness to 1 μm or more.
Even at the upper limit of 3σ, it is suppressed to 0.3 mm or less, and it can be seen that according to the present invention, the effect of remarkably suppressing the outflow amount occurs according to the present invention by only slightly roughening 1 μm. As described above, the width and the surface roughness of the resin inflow prevention portion 2b are preferably in the above ranges.

The above-mentioned roughening is performed by a chemical treatment, for example, a chemical soft etching or the like, and irregularities are randomly arranged. It is desirable that this be done. Here, soft etching refers to etching in which the etching rate of copper is lower than that of ferric chloride or the like and the amount of etching can be controlled by time.

The above-described soft etching is performed, for example, by using MECetchBOND CZ-8100 manufactured by Mec Corporation.
Is heated to 20 to 40 ° C. and sprayed on the surface to be etched for about 20 seconds to 3 minutes at a pressure of 0.5 to 3 kg / cm ² ,
After that, the substrate is washed with pure water by a pressure spray of 0.5 to ³ kg / cm ² , and then pickled with ² to 5% by weight of hydrochloric acid, and washed with three stages of pure water, followed by drying with an air knife and a spin dryer. It is.

The line length of the roughened cross section of the surface of the resin inflow prevention portion 2b with respect to a predetermined horizontal distance (the surface roughness is 1 to
(In the case of 5 μm) is 4.5 to 9 times, and it is preferable that the orientation and the portion are within the above range.
Specifically, MECet manufactured by Mec Co., Ltd. under the above conditions
Performed using chBOND CZ-8100 and when the surface roughness is 2.8 μm on average, the line length of the roughened section within a length of 20 μm is 152 μm, and the above value is 7.6 times. The line length of the roughened cross section can be measured by, for example, a surface shape measuring instrument VF-7500 manufactured by Keyence Corporation. On the other hand, when this surface roughening is performed by a belt sander (scrubber), the surface roughness becomes 1 to 3 μm.
In the case of m, the above value is 3 to 6.5 times in one direction, but is 1.0 to 1.3 times in a direction perpendicular to this. In this sense, it is more effective that the surface of the connection pad arrangement portion 2b is chemically roughened. However, in the case where the dimensions of the connection pad arrangement portion 2b are different in the upper, lower, left, and right directions, and when one of the dimensions has a margin, the effect is exhibited even in the case of a physically rough surface due to the arrangement of the rough surface.

According to the manufacturing method of the present invention, since the plating layer whose outer shape is regulated only by one-time precision of the plating resist is used for the etching resist, the shape and dimensions of the pad can be finely and accurately set. Furthermore, since the plating layer is used as the etching resist, only the upper surface of the conductor layer in the wiring region connected to the periphery of the pad can be chemically roughened, and the adhesion of the coating layer by prepreg or the like can be strengthened.

Next, another example of the method of manufacturing a wiring board according to the present invention will be described with reference to FIG. The wiring board manufactured by this manufacturing method is of a type in which a coating layer is formed on portions other than the pads 4 of the conductor layer 2.

First, the steps up to the formation of the pad 4 were performed as shown in FIG. 1D (FIG. 3A).
In this case, the plating resist 25 serving as a coating layer is used.
Is preferably about 10 to 30 μm.

Thereafter, the plating resist 25 was not removed but was left as it was, and the surface of the plating resist 25 was roughened (FIG. 3B).

The coating layer mainly includes epoxy,
A resin such as acryl, polyimide, urethane, or phenol is used, and it is preferable that the surface of these coating layers be roughened by chemical etching. This chemical etching is performed using, for example, a high sulfuric acid etching bath or a high chromic acid etching bath. The composition of the high sulfuric acid etching bath is preferably 540 ml / l of sulfuric acid (H ₂ SO ₄ ) and 20 to ₃₀ g / l of chromic anhydride (CrO ₃ ), and the etching is performed at a temperature of 65 to 70 ° C. It is preferably carried out by immersing in a bath for 20 to 30 minutes. The composition of the high chromic acid etching bath is 400 g / l of chromic anhydride (CrO ₃ ), sulfuric acid (H ₂ SO 4).
₄ ) Preferably 200 ml / l, etching is carried out in the above bath set at a temperature of 65-70 ° C.
It is preferable to carry out by immersion for a minute. In some cases, pre-etching may be performed before this etching.

As described above, when the surface of the coating layer on the conductor layer is used as a resin flow preventing portion or the like, a resin layer such as a plating resist can be used as a permanent resist. it can. Also,
Since the uneven portion of the wiring board is filled with the permanent resist, flatness can be ensured.

Further, since the surface of the resist is shaved by the surface roughening for the resin inflow prevention portion, the filler component having good adhesiveness contained in the resist is exposed, so that the resin adhesive force in the resin layer is improved, When printing is performed on the portion where the adhesive layer is formed, the adhesion of a printing agent or the like is increased, and the cleaning agent resistance is greatly improved.

[0042]

EXAMPLE 1 A wiring board having the structure shown in FIG. 4 was manufactured as follows. First, as shown in FIG.
0.5 mm thick BT resin base material (CCL-HL830) manufactured by Mitsubishi Gas Chemical Co., Ltd.
The conductor layer 2 was formed on the upper surface of the base material 1 which was a. A wiring pattern having a desired shape is formed on the conductor layer 2. Thereafter, as shown in FIG. 1B, the entire surface of the conductor layer 2 was physically roughened with a scrubber. This scrubber treatment is intended for roughening, but is mainly intended for removing an oxide film on the surface. When the surface roughness was measured,
It was 0.5 μm. When the line length of the roughened cross section in a length of 20 μm was measured with the surface shape measuring device VF-7500 manufactured by KEYENCE CORPORATION, the length was 20 μm
Times), and the width was about 130 μm (6.5 times).

Next, as shown in FIG. 1C, the surface of the conductor layer 2 other than the electronic component connection pad arrangement portion 2a was covered with a photosensitive plating resist layer 25. The area of the connection pad arrangement portion 2a was set to be about 10% larger than the size of a chip element to be installed later. Plating resist layer 25
Had a thickness of 25 μm. Thereafter, using the plating resist layer 25, only the connection pad arranging portion 2a is sequentially laminated with a copper plating layer having a thickness of 10 μm, a nickel plating layer having a thickness of 5 μm, and a gold plating layer having a thickness of 1 μm. A plating layer was applied to form a pad 4 (see FIG. 1D).

Thereafter, the plating resist 25 was removed with an alkaline solution (see FIG. 1E), and then the pad 4 was removed.
Is used as an etching resist to chemically roughen the surfaces of the portions of the conductor layer 2 other than the pad portions (the resin inflow prevention portion 2b and the resin layer formation portion 2c) (FIG. 1F).
reference).

This chemical surface roughening is performed by heating MECetchBOND CZ-8100 manufactured by Mec Co., Ltd. to 35 ° C., spraying the surface to be etched at a pressure of ² kg / cm ² for 1 minute, and then using pure water. Washing was performed at a pressure of 1 kg / cm ² , then, pickling with 3.5 wt% hydrochloric acid and washing with three stages of pure water, followed by drying with an air knife and a spin dryer. Observation of the etched surface with an SEM revealed that concave portions having various diameters were randomly arranged, and the surface roughness was measured to be about 3 μm. Further, when the line length of the roughened cross section in the length of 20 μm was measured, it was 152 μm (7.6 times) in any direction.

Next, a SAW chip was prepared as the chip element 10. The size of this SAW chip is 1.5m vertically
mx 1.5 mm in width. A gold bump 11 having a diameter of 100 μm is attached to this SAW chip.

The chip element 10 was face-down bonded by ultrasonic bonding using the bumps 11 on the pads 4 of the wiring board prepared as described above (ie, the structure shown in FIG. 4).

Finally, the attachment 30 as a lid was bonded using the prepreg 20. This lid is made of a BT resin having a thickness of 0.8 mm, and has a size of 3.8 mm in length × 3.8 mm in width, and has a depth of 0.1 mm to form a space for accommodating the chip element 10. A 5 mm recess is provided. The prepreg 20 was set so that its side face was separated from the side face of the pad 4 by about 300 μm, and was used as the resin inflow prevention portion 2b. Therefore, the portion of the conductor layer 2 below the prepreg 20 becomes the resin layer forming portion 2c.

As the prepreg, a BT resin GHPL-830NF manufactured by Mitsubishi Gas Chemical Co., Ltd. having a thickness of 60 μm was used.
Was used. Adhesive curing of the lid by prepreg 20 is 30k
By heating at 200 ° C. under a pressure of g / cm ² for 2 hours. According to this, the high fluidity component flowing out of the prepreg could be spread within the resin inflow prevention portion 2b within the range of about 300 μm which is its width.

In the case of the conventional structure as shown in FIG. 6, the distance between the outer surface of the chip element and the inner surface of the prepreg must be about 0.6 μm. About twice as much as Therefore, conventionally, the size of the lid must be 4.4 mm in length × 4.4 mm in width, and the area of the lid according to the embodiment of the present invention is about 25% of the area of the conventional lid. Could be reduced.

Embodiment 2 This embodiment is an example of a wiring board in which a coating layer (permanent resist) is applied around the pads of the conductor layer 2 and the surface of the coating layer is used as the above-described resin inflow preventing portion and the resin layer forming portion. .
This wiring board was manufactured as follows. FIG. 3 is an explanatory diagram illustrating the steps of manufacturing the wiring board according to the second embodiment.

First, the steps up to the formation of the pad were performed as shown in FIG. 1D of the first embodiment (FIG. 3).
(A)).

Thereafter, the surface of the plating resist 25 was chemically etched without removing the plating resist 25 (FIG. 3B). This chemical etching was carried out by immersing in a high sulfuric acid etching bath (temperature: 65 ° C.) having a bath composition of 540 ml / l sulfuric acid (H ₂ SO ₄ ) and 20 g / l chromic anhydride (CrO ₃ ) for 20 minutes. The surface roughness of the plating resist 25 is 3.0 μm
Met.

After that, the attachment 30 as a lid was adhered to the plating resist 25 using the prepreg 20 in the same manner as in the first embodiment. The side surface of the prepreg 20 was set to be about 300 μm away from the side surface facing the pad 4, and a part of the surface of the plating resist 25 was defined as a resin inflow prevention portion 2 b.

Also in the case of this embodiment, the component having a high fluidity flowing out of the prepreg is used as the resin inflow prevention portion 2.
The spread at b could be kept within the range of about 300 μm which is the width.

[0056]

According to the manufacturing method of the present invention, after a part of the upper surface of the conductor layer is covered with the metal plating layer for forming the pad, the conductor layer is covered with the metal plating layer using the metal plating layer as a mask. Since the upper surface of the conductive layer is chemically roughened, a highly accurate wiring board can be provided.

Further, according to the present invention, the upper surface is chemically roughened by using the pad as an etching resist while leaving the coating layer such as a resist provided for forming the pad. Thus, a highly accurate wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an example of a method of manufacturing a wiring board according to the present invention.

FIG. 2 is a graph showing the relationship between surface roughness and the amount of prepreg flowing out.

FIG. 3 is a view for explaining another example of the method for manufacturing a wiring board according to the present invention.

FIG. 4 is a cross-sectional view showing an example of the structure of a wiring board on which chip elements manufactured by the manufacturing method of the present invention are surface-mounted.

FIG. 5 is a cross-sectional view showing a main structure of the wiring board of the present invention shown in FIG. 4;

FIG. 6 is a cross-sectional view showing the structure of a conventional wiring board on which chip elements are surface-mounted.

FIG. 7 is a cross-sectional view of a principal part explaining details of the conventional wiring board shown in FIG. 6;

FIG. 8 is a diagram for explaining manufacturing steps when it is assumed that the wiring board having the structure shown in FIGS. 4 and 5 is manufactured by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Conductive layer 2a Electronic component connection pad arrangement part 2b Resin inflow prevention part 2c Resin layer formation part 4 Electronic component connection pad 10 Chip element 20 Pre-preg 30 Mounted object

Continuation of front page (72) Inventor Kenji Honda 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (3)

[Claims] In a method of manufacturing a wiring board provided with a connection pad formed of a plating layer on a part of a conductor layer on a substrate, etching is performed when the conductor layer is chemically roughened. Select a metal that can be a resist, so that the metal forms at least the top of the connection pad,
A pad forming step of forming a connection pad by metal plating a part of the upper surface of the conductor layer; and chemically roughening the upper surface of the conductor layer not covered by the connection pad using the connection pad as an etching resist for connection. Forming a top surface that is rougher than the top surface of the conductor layer covered by the pad on the conductor layer around the pad. 2. A method of manufacturing a wiring board, comprising: a connection pad formed on a part of a conductor layer on a base material by a plating layer; and a coating layer provided around the connection pad on the conductor layer. When chemically roughening the coating layer, a metal which is not roughened is selected by means for chemically roughening the coating layer, and this metal forms at least the uppermost portion of the connection pad. A pad forming step of forming a connection pad by metal-plating a part of the upper surface of the conductor layer, and chemically roughening the upper surface of the cover layer so that the upper surface of the conductor layer covered by the connection pad is A chemical roughening step of forming a rough upper surface on the coating layer around the pad. 3. The method according to claim 1, wherein the conductor layer is formed of copper, and a metal forming at least an uppermost portion of the connection pad is gold.