JPH0955583A - Multilayer wiring board and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability of connection by a structure wherein at least a part of via wiring is connected, at at least one end, with a planar wiring through a conductive bonding material and the temperature for exhibiting adhesion of a film insulation material is set lower than the bonding temperature of conductive bonding material. SOLUTION: The multilayer wiring board comprises a laminate of a plurality of planar wiring layers 100 and a plurality of via wiring layers 110, wherein the planar wiring layer 100 comprises a film 21 of insulation material exhibiting adhesion through heating, and a planar wiring 22 of conductor. The via wiring layer 110 comprises a via wiring 24 of conductor, and a film 21 of insulation material wherein at least a part of via wiring 24 is connected, at least one end, with the planar wiring 22 through a conductive bonding material 28. The temperature for exhibiting adhesion of the insulation material in the film 21 is set lower than the bonding temperature of conductive bonding material 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board used for a multi-chip module or the like and a method for manufacturing the same,
The present invention relates to a thin film wiring sheet used for manufacturing the multilayer wiring board and a manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, in order to interconnect semiconductor devices and the like, a thin film multilayer wiring board which enables high density wiring has been used. As a method of manufacturing this thin-film multilayer wiring board, there is known a method of successively laminating multiple wiring layers by repeatedly forming an upper wiring layer on the surface of a lower wiring layer. However, with this method, the cost becomes high and the time required for manufacturing is long. So, in order to solve these problems, for example,
In the technique described in Japanese Patent Laid-Open No. 63-274199, each wiring layer is separately manufactured as a thin film wiring sheet, and they are collectively laminated to obtain a thin film multilayer wiring board.

[0003]

However, in the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 63-274199, the connection between the wiring layers is made only by the mutual diffusion of the wiring materials, so that a stable contact is made. It was difficult to obtain sufficient connection reliability.

Therefore, an object of the present invention is to provide a multilayer wiring board having high connection reliability, a method of manufacturing the board, and a thin film wiring sheet used in the method.

[0005]

In order to achieve the above object, the present invention provides a multilayer wiring board including a thin film laminate having a plurality of planar wiring layers and a plurality of via wiring layers, Is provided with an insulating film made of an insulating material that exhibits adhesiveness by heating, and planar wiring made of a conductor, and the via wiring layer is a via wiring made of a conductor,
An insulating film made of an insulating material is provided, and at least a part of the via wiring has at least one end on the planar wiring,
Conductive connection through a conductive bonding material, the temperature at which the adhesiveness of the film insulating material is expressed is a multilayer wiring board characterized by being lower than the bonding temperature of the conductive bonding material,
A manufacturing method thereof is provided.

Further, according to the present invention, at least a part of the via wiring is provided with a plane wiring and a via wiring made of a conductor and at least a part of an insulating film made of an insulating material exhibiting adhesiveness by heating. At least one end thereof is conductively connected to the planar wiring through a conductive bonding material, and the temperature at which the adhesiveness of the film insulating material is expressed is lower than the bonding temperature of the conductive bonding material. Provided are a method for manufacturing a multilayer wiring board in which thin film wiring sheets are laminated together, and a multilayer wiring board manufactured by the method.

[0007]

In order to stably join the wiring, the present invention joins the wiring through the conductive joining material. However, as a result of studying joining of wirings using a conductive joining material, the following two problems occurred.

First, the thermal stress generated when the conductive bonding material is heated and melted may cause the disconnection of the bonding portion of the wiring.

Secondly, the molten conductive bonding material may spread by wetting and may come into contact with wiring other than a predetermined bonding point to cause a short circuit.

Therefore, the present invention has solved these problems by the following means. First, in order to solve the problem of the first disconnection, a detailed study was conducted on the relationship between the temperature at which the insulating film is bonded and the temperature at which the conductive bonding material is bonded.
It has been found that it is necessary to use, as the insulating film material, a material having the property that the adhesiveness is developed by heating and the adhesive temperature (the temperature at which the adhesiveness is exhibited) is lower than the bonding temperature of the conductive bonding material. That is, it has been found that the problem of disconnection can be solved by using such an insulating film material and a conductive bonding material.

The insulating film material that can be used here is a polymer material having a low adhesion temperature, good heat resistance, and good film properties (especially elongation property), for example, polyamide, polyamideimide, polysulfone, polyether. Sulfone, polyetherimide, softening-melting type polyimide, etc. can be used. Specifically, a thermoplastic polymer having any of the repeating units represented by the following general formulas (Formula 1) to (Formula 6) is particularly suitable as the insulating film material. These polymeric materials soften (or melt) at a relatively low temperature (70 ° C to 400 ° C) below the glass transition point.
This is because the adhesiveness is exhibited. The bonding temperature is
Usually, the temperature is 10 to 20 ° C. higher than the softening (or melting) temperature. In the present invention, it is desirable to form the insulating film using these materials, but instead of using these materials as the insulating film material, they can be used as an adhesive for interlayer adhesion. In this case, an adhesive layer made of these materials may be formed on the surface of the insulating film, and a planar wiring may be formed on the surface of the adhesive layer. The weight average molecular weight of the polymer material used as the insulating material in the present invention is preferably 20,000 or more from the viewpoint of mechanical properties, and in the case of polyimide, it is usually about 20,000 to 100,000.

[0012]

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[0013]

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[0014]

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[0015]

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[0016]

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[0017]

[Chemical 6]

The softening point or melting point of each material is not uniform because it is determined depending on its structure and the like, but some of these materials are listed in Table 1 as specific examples. Table 1
It is desirable that each of the materials shown in 1) be bonded at a temperature 10 to 20 ° C. higher than the softening (or melting) temperature.

[0019]

[Table 1]

The conductive bonding material used in the present invention may be, for example, an alloy of gold and tin, an alloy of gold and germanium, an alloy of lead and tin, an alloy of silver and tin, or the like. In the present invention, of these material systems, those having a bonding temperature higher than the bonding temperature of the insulating film material are appropriately selected and used. The bonding temperature of each material system is determined according to its composition and is not uniform, but some of these material systems are listed in Table 2 as specific examples.

[0021]

[Table 2]

Next, when the problem of the second short circuit was examined, it was found that the problem can be solved by using a conductive bonding material having a bonding temperature higher than the bonding temperature of the insulating film material as described above. When such a material is used, the insulating film material adheres to the conductive bonding material including the periphery of the conductive bonding material before the conductive bonding material melts and spreads at the time of bonding. Because it suppresses. Therefore, by using such a material, a short circuit due to excessive wetting and spreading of the conductive bonding material can be prevented.

In order to secure the connection of the wiring, it is preferable that the amount of the conductor connecting material is large. In addition, if the portions where the conductor connecting material is sandwiched are overlapped in multiple layers, there is a problem in that only the portions that are protruded from the surface of the insulating film are thickened as in the case where the wirings are overlapped.

Therefore, in the present invention, it is desirable to provide a connection concave portion in the exposed portion of the via wiring on the surface of the thin film wiring sheet in order to prevent the conductor connection material from spreading when wet. By doing so, the conductor connecting material remains in the recess, so that it is possible to use a sufficient amount of the conductor connecting material for connection while keeping the wetting and spreading to the outside to the extent that a short circuit does not occur. This works particularly effectively when forming a high-density circuit with a narrow wiring pitch. In addition, the recesses eliminate or reduce the step due to the connecting material.

The size of the connection recess is determined according to the wiring width, the wiring density, and the amount of the conductor connecting material used. Further, the shape of the recess may be any shape as long as it can prevent the conductor connecting material from spreading and wetting. For example, a groove surrounding the exposed portion of the via wiring is formed and used as a connection recess. can do. Further, a recess having an opening wider than the exposed portion of the via wiring may be provided on the surface of the insulating film so that the end of the via wiring is exposed at the bottom of this recess. In this case, the recess is
For example, a cylinder having a diameter of about 1.5 to 2 times the diameter of the via wiring and a depth of about 0.5 times the height of the via wiring is used. For example, as shown in FIG.
In the case of μm, the thickness of the insulating film 11 is 20 to 60 μm,
The diameter of the via wiring 16 is set to 10 to 60 μm. At this time, if the pitch of the via wiring is about 300 μm,
The connection recess 17 has a diameter of 20 to 100 μm and a depth of 5
It is desirable to set the thickness to ˜40 μm.

The shape of the recess is not limited to the cylindrical shape. The shape of the recess is preferably such that the area of any parallel cross section between the opening of the recess and the recess is equal to or less than the area of the opening. This is because if the shape is such that the inside is not wider than the opening, voids are unlikely to remain inside the recess. Examples of such a shape include a prismatic shape, a cylindrical shape, and a truncated cone shape.

Further, in order to prevent a portion not filled with the conductor connecting material from remaining as a void, the amount of the conductor connecting material used for the connection is the same as or slightly larger than the volume of the connecting recess. It is desirable that the amount is such that wetting and spreading do not cause a short circuit.

Further, in the above-mentioned prior art, the plane wiring and
Via wirings for achieving continuity between planar wirings are formed on separate thin film wiring sheets. Therefore, since the film including the planar wiring portion and the film including the via wiring for connecting them are not integrated, the number of connection points becomes very large, which causes the yield to deteriorate.

Therefore, in the present invention, the via wiring is formed by forming a via hole reaching the wiring on the other surface of the insulating film in which the wiring is embedded on the one surface and the back surface, and filling it with a conductor. As a result, a thin film wiring sheet having both planar wiring and via wiring can be obtained. In this thin film wiring sheet, at least a part of the planar wiring is exposed to the outside of the insulating film, and the rest is embedded in the insulating film. Also,
The via wiring has one end connected to the planar wiring and the other end exposed to the outside of the thin film wiring sheet. In the present invention, by providing the plane wiring and the via wiring on one film as described above, it is possible to reduce the number of layers to be laminated and reduce the inter-layer joint portion of the conductor.

When used for interconnection of semiconductor devices or the like, a thin film multilayer wiring board is often used by further adhering it onto a thick film wiring board. When used in this manner, it is desirable that the thin-film multilayer wiring board has less expansion due to heat. This is because if the thermal expansion is large, the thin film substrate may be separated from the thick film substrate due to the thermal stress generated when the semiconductor device or the like is mounted on the thin film multilayer wiring substrate.

However, the thermoplastic polymer material used for the insulating film of the thin film wiring sheet in the present invention generally has a large coefficient of thermal expansion. Therefore, in order to suppress the thermal expansion of the insulating film,
It is desirable to have a three-layer structure in which a first layer and a third layer made of a thermoplastic polymer material sandwich a second layer made of a low thermal expansion polymer material. In particular, the thin film portion of the thick film / thin film multilayer wiring board (the portion where the thin film wiring sheets are laminated)
When the total thickness exceeds 150 μm, peeling due to thermal stress is likely to occur, and thus it is effective to prevent the occurrence of defects by making the insulating film into such a three-layer structure.

The above-mentioned thermoplastic polymer materials can be used as the thermoplastic polymer materials of the first layer and the third layer. Further, the low thermal expansion polymer material of the second layer preferably has a thermal expansion coefficient of 20 ppm / ° C. or less, and for example, polyimide having low thermal expansion can be used. As the low thermal expansion polymer material for the second layer in the present invention, it is particularly preferable to use the polyimide represented by the following (Chemical formula 7).

[0033]

[Chemical 7]

Next, an example of a method for manufacturing a multilayer wiring board according to the present invention will be described with reference to FIG.

First, a composite film comprising an insulating film 11 and a conductor layer 12a, which is softened by heating and capable of being bonded, is prepared (FIG. 1 (a)). The composite film 19 is obtained, for example, by forming a thermoplastic polymer film on the surface of the conductor film 12a. The method for forming the thermoplastic polymer film 11 in this case is, for example, a method in which a varnish obtained by dissolving the above-mentioned thermoplastic polymer (or its precursor) in a solvent is applied to the surface of the conductor film and heated. . The composite film 19 can also be obtained by forming the conductor film 12a on the surface of the insulating film 11 which is a thermoplastic polymer film. In this case, the conductor film 12a may be formed by vapor deposition, sputtering, plating, or the like of the conductor on the surface of the insulating film 11.

Then, unnecessary portions of the conductor layer 12a are removed by etching, and patterning is carried out, so that the plane wiring 12 is formed.
Is obtained (FIG. 1 (b)). Note that, for example, a well-known photolithography technique can be used to remove the unnecessary portion of the conductor layer 12a. However, the method of forming the planar wiring 12 is not limited to this, and another method such as an additive method may be used.

Next, the via hole 13 is formed by a method such as laser, dry etching, and wet etching (FIG. 1C), and the via hole 13 is filled with a conductor to form a via wiring 14 (FIG. 1D). )).

Here, in order to provide the connection concave portion,
The via hole is a cylindrical shape 1 as shown in FIG.
Instead of 3, the via hole 13 may have a widened opening as shown in FIG. For example, if a cylindrical hole 17 having a larger diameter and a shallower depth than the via hole 17 is formed in the opening of the via hole 13 concentrically with the via hole, the hole having the two-stage structure shown in FIG. Is obtained. In this way, the connection recess 17a
After forming the, if the via hole 15 is filled with a conductor,
The via wiring 18 is obtained (FIG. 1 (f)). Alternatively,
A groove surrounding the exposed portion of the via wiring 14 may be formed as a connection recess.

As described above, the thin film wiring sheet 20 including the planar wiring 12 and the via wirings 14 and 16 is obtained.

As described above, in the case where the total thickness of the laminated sheets exceeds 150 microns, the insulating film 11 has the structure shown in FIG. It is desirable to use a film 11a having a three-layer structure as shown. FIG. 7 shows a composite film 19 in which a conductor layer 12a is formed on the insulating film 11a. This three-layer film 11a
Is a first layer 111 and a third layer 113 made of a material that is softened by heat (preferably a thermoplastic polymer), and a second layer 112 made of a low thermal expansion polymer sandwiched between them.
Consists of As described above, by using the three-layer insulating film 11a having the low thermal expansion polymer layer 112 in the middle of the film, it is possible to prevent the thin film from peeling from the thick film substrate. Further, when the laminated thin film wiring sheets are pressure-bonded, the planar wiring of the lower layer is embedded in the third layer of the upper layer, but if a layer that is not softened by heat is provided in the middle of the insulating film, the surface of the first layer can be provided. The formed planar wiring and the third
This is preferable because contact with the wiring embedded in the layer can be avoided.

It is desirable that the film thicknesses of the first layer and the third layer be 5 to 10 μm and the film thickness of the second layer be 10 to 50 μm. It is desirable that the thickness of the three layers be equal to or larger than the thickness of the planar wiring laminated on the lower layer.

The insulating film 11a is formed, for example, by heat-polymerizing a polyimide precursor varnish to form a film 112 of low thermal expansion polyimide, and after performing treatment such as ashing on both front and back surfaces, Applying a solution of a thermoplastic polymer or its precursor and heating,
Alternatively, it can be manufactured by applying the molten thermoplastic polymer and drying it to form the first layer 111 and the third layer 113.

After the desired number of thin film wiring sheets have been produced by the above steps, the conductor connecting material such as solder is laminated at the connection points of the wiring while being laminated, and heated in a baking oven or on a hot plate. A thin film multilayer wiring board is obtained by applying pressure and adhesive connection. Further, a thick-film thin-film composite multilayer wiring board can be obtained by laminating on a desired thick-film board and pressurizing at high temperature for adhesive connection.

In the present invention, in this adhesive bonding, the insulating films 11 or 111 and 113 are first softened to bond the layers, and when the sound is further adjusted, the conductive bonding material is connected. Therefore, in thermocompression bonding of the laminated body, it is desirable that the laminated body is heated to the bonding temperature of the insulating material and held for a certain period of time and then heated to the bonding temperature of the conductive bonding material and held for a certain period of time.

At the time of this adhesive connection, it is desirable to reduce the pressure of the entire system in order to leave no air bubbles between the layers, and furthermore, press from the thin film side to the thick film side by applying a force using a flat plate or the like. Is desirable. The depressurization during stacking is 1
It is desirable to set the pressure to 1/000 atmospheric pressure or less.

When the insulating film 21 is formed by using a material which is softened by heating, as shown in FIG. 10, a conductor film 21a (shown in FIG. 10A) formed on the insulating film 21 is formed. After patterning and forming the planar wiring 22 (shown in FIG. 10B), the insulating film 21 is heated and softened, and then the planar wiring 22 is pressed to be embedded in the insulating film 21 (FIG. 10C). )), It is desirable to form via wiring (FIG. 10D) so as to contact the embedded planar wiring. By doing so, it is possible to suppress the bending of the thin film wiring sheet due to the superposition of the planar wiring and the via wiring, and the problems such as the phenomenon of adhesion, the disconnection and the short circuit of the wiring caused by this are not caused. The insulating material of the insulating film is preferably a thermoplastic polymer material. This is because the thermoplastic polymer material has little dimensional change before heating and after cooling. If a thermoplastic polymer material is used as the insulating film material, the dimensional accuracy during thermocompression bonding is good.

In FIG. 10 (e), the via wiring 24
The groove 91 is formed around the exposed portion of the above, and the thin film wiring sheet 90 provided with the connection concave portion is illustrated. As described above, when the groove 91 is formed as the connection recess, it is desirable to fill the via hole with the conductor. This is because the groove 91 can be prevented from being filled with the via conductor.

According to the film laminating method of the present invention, it is possible to form a multilayer wiring circuit with high reliability and at low cost by the thin film technique. This is because the bonding temperature of the insulating adhesive to be used is lower than the bonding temperature of the conductive bonding material to minimize the stress applied to the bonding interface, thereby preventing disconnection. Furthermore, this has the effect of suppressing excessive wetting and spreading of the conductive bonding material,
Prevents short circuit. Further, when the conductive bonding material is applied in a large amount, it is desirable to prevent a short circuit by providing a connection concave portion that suppresses wetting and spreading.

[0049]

Embodiments of the present invention will be described below with reference to the drawings. Table 3 shows the material of the insulating film used in each example and comparative example.

[0050]

[Table 3]

Example 1 In this example, as shown in FIG. 2, a thin film / thick film composite multilayer wiring board was manufactured by the following steps A to C.

A. Fabrication of Thin Film Wiring Sheet By repeating the following steps (1) to (4), the copper wiring 22 and the via wiring 24 are provided, and one side is 10 mm.
Three square thin film wiring sheets 20 were manufactured.

(1) First, an acid dianhydride represented by the following structural formula (Formula 8)

[0054]

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And a diamine represented by the following structural formula (Formula 9)

[0056]

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A polyetherimide precursor varnish (solids concentration 20 w / w%) obtained by polymerizing and in a solvent (N-methylpyrrolidone) is applied to the surface of a copper foil 22a having a thickness of 5 μm and then heated. By curing to form an insulating film 21 having a thickness of 35 μm, a composite film 22b shown in FIG. 2A was produced.

The insulating film 21 thus obtained has the material number 1 shown in Table 3.
It consists of polyetherimide having the structure shown as.

(2) Next, a positive type resist film is formed on the copper film 22a, exposed through a mask having a predetermined pattern, developed, and then copper is etched to remove the resist, The wiring 22 was obtained (FIG. 2 (b)). Here, the wiring width is 20 μm, and the closest distance between the wirings 22 is 50 μm.
The wiring pitch was 70 μm.

(3) Finally, using an excimer laser,
A via hole 23 is formed in a desired portion of the insulating film 21 (FIG. 2C), and copper is filled in the via hole 23 by an electroless plating method to obtain a via wiring 24 (FIG. 2).
(D)). Thus, the thin film wiring sheet 20 (the first layer thin film wiring sheet 20a, the second layer thin film wiring sheet 20b, and the third layer thin film wiring sheet 20c) including the planar wiring 22 and the via wiring 24 was obtained. Note that other methods such as selective etching may be used to form the via holes.

B. Preparation of surface electrode Nickel foil was used instead of copper foil 22a, and the above (1)
A thin film wiring sheet was produced in the same manner as in (3) to (3). As a result, instead of the copper wiring 22, the nickel surface electrode 25
Thus, a thin film wiring sheet for uppermost layer 20d was obtained.

C. Lamination Next, as shown in FIG. 2E, on the alumina-based ceramic substrate 26 having the tungsten wiring 27 inside,
The first layer thin film wiring sheet 20a, the second layer thin film wiring sheet 20b, the third layer thin film wiring sheet 20c, and the uppermost layer thin film wiring sheet 20d were laminated in this order. At this time, the solder 28 is adhered onto the planar wiring 22 of the lower layer, which will face the exposed portion of the via wiring 24 of the upper layer due to the lamination, and then the upper layer is laminated to form the solder 2
8 was inserted into the connection point between the lower layer wirings 22 and 27 and the upper layer via wiring 24. It should be noted that the solder was applied by melting the solder by covering the connection part of the wiring 22 with a solder sheet made of 97% tin and 3% silver and having a thickness of 5 μm and then heating the connection part.

Ceramic substrate 2 laminated in this way
6 and the thin film wiring sheet 20 are placed on the hot plate in the vacuum chamber with the thin film side facing up, and the inside of the chamber is set to 1
While reducing the pressure to 1/0000 atm, while applying downward pressure to the laminated body from above the thin film wiring sheet 20d for the uppermost layer using a flat plate, the temperature of the hot plate is increased from room temperature by 2 ° C. per minute, After being kept at 210 ° C. for 60 minutes, the temperature is further raised to 260 ° C. and then lowered, so that each layer 20a-
A laminated body of d and 26 was obtained.

Finally, the laminate was taken out of the chamber,
A thick film / thin film composite multilayer wiring board for a multi-chip module shown in FIG. 3 is formed by connecting signal input / output pins 30 to the side of the thick film board 26 on which the thin film wiring sheet 20 is not laminated, through solder 29. Was completed. In the obtained thick-film / thin-film composite multilayer wiring board, the material of the insulating film 22 of the upper layer is filled in the gap of the planar wiring 21 by pressure bonding, and the planar wiring 21 and one of the filled insulating film 22 of the upper layer are The planar wiring layer 100 is formed by the parts. Here, the surface electrode 25 side is the top and the ceramic wiring board side is the bottom. Further, the via wiring layer 110 is formed by the via wiring 24 and a part of the insulating film 21.
The via wiring layer 110 and the planar wiring layer 100 are alternately laminated. One end of the via wiring 24 is directly joined to the upper plane wirings 22 and 25, and the other end is connected to the lower plane wirings 22 and 27 via solder 28.

As a result of the continuity test, it was found that the completed multilayer wiring board had no problem and that all the electrical connections were made well.

Example 2 An alloy of tin and silver (80% gold, 20% tin) was used as the solder material 28 for interlayer bonding, and after the thin film wiring sheet 20 was laminated on the alumina-based ceramic substrate 26. Example 1 was repeated except that the heating conditions in the heating step were held at 210 ° C. for 60 minutes and then raised to 260 ° C. instead of holding at 210 ° C. for 60 minutes and then raised to 320 ° C. In the same manner as above, a thick film / thin film composite multilayer wiring board for a multi-chip module was completed. Also in this example, it was found that the completed multilayer printed circuit board had no problem in the continuity test and good electrical connection as in the case of Example 1.

<Embodiment 3> This embodiment is the same as Embodiment 3 except that instead of using the single-layer film 21 used in Embodiment 1, a three-layer film 31 shown in FIG. 4 is used. In the same manner as in Example 1, a thick film / thin film composite multilayer wiring board used for a multichip module was produced. This embodiment is the same as the first embodiment.
Instead of (1) in the thin film wiring sheet manufacturing process in
It differs from Example 1 only in that the composite film 33 shown in FIG. 4 was produced and the composite film 33 was used as a starting material in (2) of the thin film wiring sheet production process. Therefore, here, only the method for producing the composite film 33 will be described.

First, an acid dianhydride represented by the following structural formula (Formula 10)

[0069]

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And the following structural formulas (formula 11), (formula 12),
Alternatively, a mixture of three kinds of diamines represented by (Chemical Formula 9) (the molar ratio is (Chemical Formula 11) :( Chemical Formula 12) :( Chemical Formula 9) =
70:20:10)

[0071]

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[0072]

[Chemical 12]

[0073]

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Polyimide precursor varnish (solid content concentration 15 w / w%) obtained by polymerizing and in a solvent (N-methylpyrrolidone) is applied on a flat supporting substrate surface and heat-cured, 20 μm thick second insulating layer 3
12 was formed. The second insulating layer 312 obtained is shown in Table 3.
It is made of polyimide having the structure shown as Material No. 2. The coefficient of thermal expansion of this polyimide is 8 ppm.

Next, after ashing the surface of the obtained polyimide film 312, the same polyetherimide precursor varnish as that used in Example 1 was applied to the surface and heat-cured to form a 15 μm-thick first film. The insulating layer 113 of No. 3 was formed. The third insulating layer 313 thus obtained is shown in Table 3 under Material No. 2
It consists of polyetherimide having the structure shown as.

Next, the obtained laminated body of the second layer and the third layer is peeled off from the supporting base material, and the exposed surface of the second layer is ashed to form the first insulating layer 311 on the surface. The same polyetherimide precursor varnish as used in Example 3 was applied and cured by heating, and the third insulating layer 3 having a thickness of 5 μm was applied.
13 was formed. As a result, the insulating film 3 having a three-layer structure in which the polyetherimide layer 313 having a thickness of 5 μm, the low thermal expansion polyimide layer 312 having a thickness of 20 μm, and the polyetherimide layer 311 having a thickness of 15 μm are laminated in this order
1 (thickness 40 μm) was obtained.

Finally, a copper film having a thickness of 1 μm was formed on the surface of the first insulating layer 311 by sputtering, and then the thickness of the copper film 22a was adjusted to 5 μm by electroplating. As a result, a composite film 33 including the three insulating layers 311 to 312 and the conductor layer 22a having a thickness of 5 μm was obtained.

Also in this example, similar to Example 1, the obtained thick film / thin film composite multilayer wiring board had good electrical connection.

Furthermore, the thick film obtained in the present embodiment
When the electrode of the semiconductor chip was soldered to the surface electrode 25 of the thin film composite multilayer wiring board, no peeling between the thin film wiring sheet 20 and the thick film substrate 26 was observed and good connection was obtained. In addition, the thickness of the thin film portion in the laminate is 4
Four thin film wiring sheets of 0 μm have a thickness of 160 μm.

Example 4 In this example, as shown in FIG. 5, a high-density multilayer wiring structure was manufactured by the following steps A to C.

A. Production of Thin Film Wiring Sheet By repeating the following steps (1) to (3), three thin film wiring sheets 20 each having a copper wiring 22 and a via wiring 24 were manufactured.

(1) First, in the same manner as in the thin film wiring sheet forming steps (1) and (2) of Example 1, an insulating layer 21 made of polyetherimide having a thickness of 40 μm and a copper film 22a having a thickness of 5 μm are formed. And a composite film 22b (see FIG. 5).
(A)) was formed and the copper film 22a was patterned to obtain the wiring 22 (FIG. 5 (b)). The wiring width is 20 μm,
The closest distance between the wirings 22 is 30 μm, and the wiring pitch is 50.
μm.

(2) Next, using an excimer laser,
A hole (that is, a hole having a depth of 40 μm) that penetrates the insulating film 21 having an inner diameter (diameter) of 30 μm and reaches the planar wiring 22 is formed in a desired portion of the insulating film 21 from the side where the wiring 22 is not formed. A hole having an inner diameter (diameter) of 40 μm and a depth of 10 μm was drilled with the same central axis as this hole. As a result, as shown in FIG. 9, the via hole 43 having an inner diameter (diameter) of 30 μm and a depth of 30 μm and the inner diameter (diameter) of 40 μm are formed.
m and a recess 41 for connection having a depth of 10 μm were formed (FIG. 5C).

The inner diameter (diameter) 40 μm and the depth 10 μm
It is also possible to first make a hole of m, and then make a hole that penetrates the insulating film 21 having an inner diameter (diameter) of 30 μm and reaches the planar wiring 22. In addition, a method such as selective etching may be used for drilling.

(3) Finally, the via hole 43 was filled with copper by the electroless plating method to form the via wiring 44 (FIG. 5D). As a result, the thin film wiring sheet 4 including the connection recess 41, the planar wiring 22, and the via wiring 44 is formed.
0 (first layer thin film wiring sheet 40a, second layer thin film wiring sheet 40b, and third layer thin film wiring sheet 40c)
was gotten.

B. Preparation of surface electrode Nickel foil was used instead of copper foil 22a, and the above (1)
A thin film wiring sheet was produced in the same manner as in (3) to (3). As a result, instead of the copper wiring 22, the nickel surface electrode 25
As a result, a thin film wiring sheet 40d for the uppermost layer was obtained.

C. Lamination Next, as shown in FIG. 5E, the tungsten wiring 2
On the alumina-based ceramic substrate 26 having No. 7, the first layer thin film wiring sheet 40a and the second layer thin film wiring sheet 40
b, the third layer thin film wiring sheet 40c, and the uppermost layer thin film wiring sheet 40d were laminated in this order. At this time, the wiring 2 in the lower layer, which is opposed to the connection concave portion 41 in the upper layer due to stacking
After placing the solder ball 48 (diameter 30 μm) on the upper layer 2, the upper layer is laminated, so that the solder ball 48 made of 97% tin and 3% silver is connected to the lower wirings 22 and 27 and the upper via wiring 44. I was caught in the connection point.

Ceramic substrate 2 laminated in this way
6 and the thin film wiring sheet 40 are placed on the hot plate in the vacuum chamber with the thin film side facing up, and the inside of the chamber is set to 1
While reducing the pressure to 1/0000 atm, a flat plate is used to apply downward pressure to the laminated body from above the uppermost thin film wiring sheet 40d, and the temperature of the hot plate is maintained at 210 ° C. for 60 minutes. After the temperature was raised to 0 ° C., the temperature was lowered and the layers 20a to 20d were pressure-bonded.

Finally, as in the first embodiment, the thick film wiring 2 is formed.
7, the signal input / output pin 30 is connected via the solder 29, and the thick film / thin film composite multilayer wiring board for the multi-chip module shown in FIG. It was

As with Example 1, the completed multilayer printed circuit board had good electrical connections.

<Example 5> The insulating layer 21 in Example 1
A thick film / thin film composite multilayer wiring board similar to that shown in FIG. 3 was completed in the same manner as in Example 1 except that the polyether sulfone shown as material number 3 in Table 1 was used as the material of . In addition, the fifth embodiment and the first embodiment are
Only the manufacturing process (1) of the thin film wiring sheet is different.
Therefore, here, this step, that is, the composite sheet 1
Only the manufacturing process of 9 will be described.

First, a pellet of polyethersulfone having the structure shown in Table 1 as material No. 3 was prepared,
This was melted by heating and kneaded. Next, the film thickness is 10 μm
Prepare an electrolytic copper foil with one surface roughened with, and on this roughened surface,
A polyether sulfone melt-kneaded in advance was applied to form a film. As a result, a composite sheet 22b of polyether sulfone and copper was obtained.

The thick-film / thin-film composite multilayer wiring board manufactured in the same manner as in Example 1 using the obtained composite sheet 22b as a starting material had no problem in the continuity test and was excellent as in Example 1. It was a substrate.

<Example 6> As the pellets of the polyether sulfone, the pellets of the polyether sulfone having the structure shown as the material number 4 in Table 1 are used,
In the same manner as in Example 5, a thick film / thin film composite multilayer wiring board was produced. The obtained multilayer wiring board was good as in Example 5.

Example 7 Polyamide pellets having the structure shown as material No. 5 in Table 1 were used in place of the polyether sulfone pellets, and the heating conditions during lamination were maintained at 290 ° C. for 60 minutes. A thick film / thin film composite multilayer wiring board was produced in the same manner as in Example 5 except that the temperature was raised to 340 ° C. and then lowered, and the composition of the solder 28 for interlayer connection was 95% lead and 5% tin. . The obtained multilayer wiring board was good as in Example 5.

Example 8 A thick film / thin film composite was prepared in the same manner as in Example 7 except that the polyamide imide pellet having the structure shown in Table 1 as material number 6 was used in place of the polyether sulfone pellet. A multilayer wiring board was produced. The obtained multilayer wiring board was good as in Example 7.

<Example 9> As the insulating film 21, a heat-meltable polyimide made of the polyimide shown as material No. 7 in Table 1 was used, and the composition of the interlayer connecting solder 28 was 95% lead and 5% tin. A thick film / thin film composite multilayer wiring board was produced in the same manner as in Example 1 except that the heating conditions in the lamination treatment were held at 290 ° C. for 60 minutes, then raised to 340 ° C. and then lowered. The obtained multilayer wiring board was good as in Example 5.

In this embodiment, the composite film 22b is used.
Is an acid dianhydride represented by the following structural formula (Formula 14)

[0099]

Embedded image

And the following structural formula (Formula 15)

[0101]

Embedded image

A polyimide precursor varnish (solid content concentration 15 w / w%) obtained by polymerizing and in a solvent (N-methylpyrrolidone) was used to form a copper foil 2 having a thickness of 10 μm.
It was prepared by applying it on the surface of 2a and curing it by heating.

<Comparative Example 1> As a solder material for interlayer bonding, a solder material composed of tin and lead and having an excessive tin content and a bonding temperature of 183 ° C. was used, and the heating condition during lamination was 183 ° C. A thick film / thin film multilayer wiring board used for a multi-chip module was manufactured in the same manner as in Example 9 except that the temperature was further held for 60 minutes and then the temperature was further raised to 250 ° C. and held for 60 minutes. The softening temperature of the polyimide used in this comparative example and Example 9 is 250 ° C.

The thick-film / thin-film composite multilayer wiring board obtained was
In the continuity test, many defects were confirmed, and it was confirmed that short-circuiting of the wiring 22 frequently occurred.

<Comparative Example 2> An example other than using the non-thermoplastic polyimide shown as the material number 8 in Table 1 as the material of the insulating film 21 in place of the polymer material softened by heat A thick film / thin film multilayer wiring board used for a multi-chip module was manufactured in the same manner as in 1. In addition,
The varnish used for forming the insulating film 21 in this comparative example is an acid dianhydride represented by the following structural formula (Formula 13).

[0106]

Embedded image

And a diamine represented by the following structural formula (Formula 9)

[0108]

Embedded image

Polyimide precursor varnish (solid content concentration 20 w / w%) obtained by polymerizing and in a solvent (N-methylpyrrolidone). After being applied to the surface of the foil 22a, it is heated and cured to form the insulating film 21 having a thickness of 35 μm, whereby a composite film 22b as a starting material was produced.
The obtained insulating film 21 is made of polyimide having the structure shown as material number 8 in Table 1.

The thick film / thin film composite multilayer wiring board thus obtained was
In the continuity test, many defects were confirmed, and it was confirmed that short-circuiting of the wiring 22 frequently occurred.

[0111]

As described above, according to the present invention, a multilayer wiring board having high connection reliability can be obtained. Therefore, according to the present invention, since a wiring having a high aspect ratio is formed with high connection reliability and collective lamination adhesive connection, a high-density multilayer wiring board used for a multi-chip module or the like can be formed with high reliability and low reliability. Can be provided at cost.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a manufacturing process of a thin film wiring sheet according to the present invention.

FIG. 2 is an explanatory diagram showing a manufacturing process of the multilayer wiring board according to the first embodiment.

3 is a schematic view of a cross section of a multilayer wiring board manufactured according to Example 1. FIG.

FIG. 4 is a schematic view of a cross section of an insulating film used in Example 3.

FIG. 5 is an explanatory view showing the manufacturing process of the multilayer printed circuit board according to the fourth embodiment.

FIG. 6 is a schematic view of a cross section of a multilayer wiring board manufactured in Example 4.

FIG. 7 is a schematic view of a cross section of an insulating film having a three-layer structure according to the present invention.

FIG. 8 is a cross-sectional view showing sizes of a via hole and a connection recess.

FIG. 9 is a cross-sectional view showing the sizes of via holes and connection recesses in the fourth embodiment.

FIG. 10 is an explanatory diagram showing an example of a manufacturing process of a thin film wiring sheet in the case of embedding a planar wiring in an insulating film and forming a groove as a connection recess.

[Explanation of symbols]

11 ... Insulating film, 12 ... Planar wiring, 12a ... Conductive film, 13
... roller, 14 ... flat plate, 15 ... via hole, 16 ... via wiring, 17 ... via hole, 17a ... connection recess,
18 ... Via wiring, 19 ... Composite film of conductor film and insulating film, 111, 113 ... Insulating layer softened by heat and capable of adhesion, 112 ... Layer of low thermal expansion material, 20, 20a
-D ... Thin film wiring sheet, 21 ... Polyetherimide insulating film, 22 ... Copper plane wiring, 22a ... Copper foil, 22b ... Composite film of conductor film and insulating film, 23 ... Via hole, 2
4 ... Via wiring, 25 ... Nickel surface electrode, 26 ... Alumina-based ceramic substrate, 27 ... Tungsten wiring, 28
... Solder piece, 29 ... Solder, 30 ... Pin, 311 ... First
Insulating layer, 312 ... Second insulating layer, 313 ... Third insulating layer, 40, 40a-d ... Thin film wiring sheet having connection recess, 41 ... Connection recess, 43 ... Via hole, 44 ...
Via wiring, 48 ... Solder ball, 49 ... Solder-filled connection recess, 90 ... Thin film wiring sheet having groove-shaped connection recess, 91 ... Groove-shaped connection recess, 100 ... Planar wiring layer, 110 ... Via wiring layer.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08G 73/10 NTF C08G 73/10 NTF C08L 71/10 LQK C08L 71/10 LQK 81/06 LRF 81 / 06 LRF

Claims (24)

[Claims] 1. A multilayer wiring board comprising a thin film laminate having a plurality of planar wiring layers and a plurality of via wiring layers, wherein the planar wiring layer is an insulating film made of an insulating material exhibiting adhesiveness by heating. And a planar wiring made of a conductor, the via wiring layer includes a via wiring made of a conductor and an insulating film made of an insulating material, and at least a part of the via wiring has at least one end formed into the planar wiring. A multi-layer wiring board, which is connected in a conductive manner via a conductive bonding material, and a temperature at which the film insulating material exhibits adhesiveness is lower than a bonding temperature of the conductive bonding material. 2. A plurality of laminated and adhered thin film wiring sheets, each of which includes a planar wiring and a via wiring made of a conductor, and an insulating film at least a part of which is made of an insulating material exhibiting adhesiveness by heating. At least one end of at least one end of the via wiring is conductively connected to the planar wiring through a conductive bonding material, and the temperature at which the adhesiveness of the film insulating material is developed is A multilayer wiring board having a temperature lower than a bonding temperature of the conductive bonding material. 3. The insulating film according to claim 2, wherein the insulating film is a laminated film having a three-layer structure of a first layer to a third layer, and the first layer and the third layer each exhibit adhesiveness by heating. The second layer is made of a low thermal expansion insulating material having a thermal expansion coefficient of 20 ppm / ° C. or less, and the temperature at which the adhesiveness of the film insulating materials of the first layer and the third layer is expressed is A multilayer wiring board, each of which has a temperature lower than a bonding temperature of the conductive bonding material. 4. The multilayer wiring board according to claim 1, wherein the insulating material exhibiting adhesiveness by heating is a thermoplastic polymer. 5. The insulating material exhibiting adhesiveness by heating according to claim 1 or 2, wherein the insulating material is at least one polymer selected from polyetherimide, polyamideimide, polysulfone, and polyethersulfone. A multilayer wiring board characterized by: 6. The multilayer wiring board according to claim 5, wherein the thermoplastic polymer has any of repeating units represented by the following structural formula groups (Chemical formula 1) to (Chemical formula 6). . Embedded image Embedded image Embedded image Embedded image Embedded image [Chemical 6] 7. The conductive bonding material according to claim 1, wherein the conductive bonding material is selected from an alloy of gold and tin, an alloy of gold and germanium, an alloy of lead and tin, and an alloy of silver and tin. A multilayer wiring board comprising at least one kind of solder. 8. The thin film wiring sheet according to claim 3, wherein the low thermal expansion insulating material is low thermal expansion polyimide. 9. The thin film wiring sheet according to claim 8, wherein the low thermal expansion polymer is a polyimide represented by the following (formula 7). [Chemical 7] 10. The thin film according to claim 1, further comprising a ceramic substrate having wiring, wherein the thin film laminated body is connected to the ceramic substrate surface, and the thin film laminated body is in contact with the ceramic substrate surface. At least a part of the wiring of the wiring sheet is connected to the wiring of the ceramic substrate so as to be conductive, and a multilayer wiring board. 11. The wiring of the thin film wiring sheet according to claim 1, wherein the wiring is a flat wiring formed on at least one of the front and back surfaces of the insulating film, and one end is exposed on the other surface of the insulating film. A multilayer wiring board, the other end of which includes a via wiring which is conductively connected to the planar wiring formed on the insulating film. 12. The multilayer wiring board according to claim 11, wherein the insulating film has a concave portion surrounding a periphery of the exposed end portion of the via wiring. 13. The multilayer wiring board according to claim 12, wherein the recess has a groove shape. 14. The multilayer wiring board according to claim 12, wherein the exposed end portion of the via wiring is exposed at a bottom surface of the recess. 15. The thin film wiring sheet according to claim 14, wherein the area of an arbitrary cross section parallel to the opening of the recess is equal to or less than the area of the opening. 16. A thin-film wiring sheet manufacturing step for manufacturing a thin-film wiring sheet, comprising: a wiring made of a conductor; and at least a part thereof made of an insulating film made of an insulating material exhibiting adhesiveness by heating. The conductive bonding material is arranged such that the portion is connected to the wiring of the other thin film wiring sheet laminated in contact with the thin film wiring sheet including the wiring through the conductive bonding material. However, it comprises a laminating step of laminating a plurality of thin film wiring sheets produced in the thin film wiring sheet producing step, and an adhesive step of thermocompression-bonding the laminated thin film wiring sheets, and manifests the adhesiveness of the membrane insulating material. The temperature for applying is lower than the bonding temperature of the above-mentioned conductive bonding material. 17. The wiring of the thin film wiring sheet according to claim 16, wherein the wiring is a flat wiring formed on at least one of the front and back surfaces of the insulating film, and one end of the wiring is exposed on the other surface of the insulating film. The other end includes a via wiring that is conductively connected to the planar wiring formed on the insulating film, and the thin film wiring sheet manufacturing step includes at least one of front and back surfaces of the insulating film. And a plane wiring forming step of forming a plane wiring on the other surface of the insulating film, and a via wiring forming step of forming a via wiring by forming a via hole reaching the plane wiring on the other surface of the insulating film and filling the via hole with a conductor. In the laminating step, at least a part of the via wiring is in contact with a thin film wiring sheet including the wiring, and another planar wiring included in the other thin film wiring sheet is laminated with a conductive bonding material. The multilayer wiring board is characterized in that it is a step of stacking a plurality of thin film wiring sheets produced in the thin film wiring sheet producing step while arranging the conductive bonding material so as to be in a position to be connected with each other. Production method. 18. The embedding step according to claim 16, wherein the thin-film wiring sheet manufacturing step further comprises a step of pressing the planar wiring formed by the planar wiring forming step to at least partially embed it in the insulating film. A method for manufacturing a multilayer wiring board, comprising: 19. The method of manufacturing a multilayer wiring board according to claim 16, wherein the laminating step includes a step of laminating the thin film sheet on a ceramic substrate having wiring. 20. The method of manufacturing a multilayer wiring board according to claim 16, wherein the adhering step is performed at a pressure of 1/1000 atmosphere or less. 21. The via wiring forming step according to claim 16, wherein a connecting concave portion forming step of forming a concave portion on a surface of the insulating film on which a via hole is formed and a via wiring reaching the planar wiring at a bottom portion of the concave portion are formed. A method of manufacturing a multilayer wiring board, comprising: a step of forming a hole; and a step of filling the via hole with a conductor to form a via wiring. 22. The method of manufacturing a multilayer wiring board according to claim 16, wherein the via hole forming step further comprises a connecting concave portion forming step of forming a concave portion around the via hole. 23. The method of manufacturing a multilayer wiring board according to claim 21, wherein the step of forming the connection recess includes the step of forming a groove surrounding the via hole. 24. The bonding step according to claim 16, wherein the heating is performed at a temperature not lower than the bonding temperature of the conductive bonding material, which is equal to or higher than the temperature at which the insulating material having the bonding property by the heating develops the bonding property. And a step of heating at a temperature equal to or higher than the bonding temperature in this order, a method for manufacturing a multilayer wiring board.