JP2002335080A - Manufacturing method of multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of multilayer wiring boards using interlayer connection, which can cope with variation in the height of wiring patterns, connect a desired wiring pattern, eliminate the need for a cove film and a plating process, and also cope with thin-line in wiring. SOLUTION: An adhesive layer has conductivity in a thickness direction and comprises a conductive particle having a particle size smaller than the distance between adjacent wiring patterns and an adhesive. The adhesive layer is arranged between at least two double-sided wiring boards where a wiring pattern is formed projecting to an insulating board. The interlayer connection is carried out by achieving lamination integration due to heating and press, one where a conductive layer is formed on the surface of a molecular nuclide is used as a conductive particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a multilayer wiring board.

[0002]

2. Description of the Related Art A multilayer wiring board can incorporate a signal circuit, a power supply, an earth circuit, and the like, and is therefore often used in various electronic devices as an effective method for increasing the wiring density. A typical method of manufacturing a conventional multilayer printed wiring board is to cover the portions other than the interconnections with a coverlay film or the like and obtain electrical insulation, and electrically connect the wiring patterns of each layer to each other by copper plating or the like. It has been done. In addition, as a relatively new attempt, the interconnects are covered with conductive particles while obtaining insulation by covering other than the interconnects with a coverlay film, mask film, resist film, etc. (collectively referred to as cover films hereinafter). It has also been proposed to connect the wiring patterns of each layer to each other using a material made of a dispersed adhesive (for example, Japanese Patent Application Laid-Open No. 61-49499 and Japanese Patent Application Laid-Open No. 2-3659).
No. 3), and solder is used as the conductive particles in this case.

[0003]

In each of the above-mentioned conventional methods, since a portion other than the interconnecting portion is covered with a cover film, two layers of the cover film exist between the opposing wiring boards, and when a multilayer wiring board is formed, the thickness is reduced. The decrease was difficult to obtain, which contributed to the cost increase. As for the interconnection method of the wiring patterns, the method of plating with copper or the like requires a complicated plating step, and has a disadvantage that the copper plating is easily broken when the cover film is thermocompressed. When the connection is made of a material composed of conductive particles and an adhesive, it is difficult to cope with variations in the height of the wiring pattern, and the practicability is poor. That is, in the case of hard conductive particles, the conductive pattern becomes a spacer, and the connection of the wiring pattern lower than this portion becomes impossible, and the soft conductive particles that are melted at the time of connection like solder and can relatively cope with the variation in the height of the wiring pattern. In such a case, it has become impossible to cope with increasingly thinning of the wiring, such as melting and connecting between adjacent wiring patterns and leaking. The present invention is directed to a multilayer wiring board using an interlayer connection that can cope with a variation in the height of a wiring pattern, can connect a desired wiring pattern, does not require a cover film or a plating step, and can also cope with thinning of wiring. Related to manufacturing method.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method of forming a conductive pattern between two or more double-sided wiring boards, each having a wiring pattern protruding from an insulating substrate, and a conductive particle having a particle size smaller than the distance between adjacent wiring patterns. The present invention relates to a method for manufacturing a multilayer printed wiring board in which an adhesive layer having conductivity is arranged in the thickness direction and the layers are integrated by heating and pressing to perform interlayer connection. That is, an adhesive having conductivity in the thickness direction comprising conductive particles having a particle size smaller than the distance between adjacent wiring patterns and an adhesive is provided between two or more double-sided wiring boards each having a protruding wiring pattern formed on an insulating substrate. A method for producing a multilayer wiring board in which conductive layers are formed on a surface of a polymer nucleus by forming conductive layers on a surface of a polymer nucleus. And
A method of manufacturing a multilayer wiring board in which five or more conductive particles are deformed and present in a part of a wiring pattern of an interlayer connection part that requires connection. A method for producing a multilayer wiring board, wherein the adhesive layer further contains hard particles that are at least equal to the distance of the opposing wiring pattern after lamination and integration and are less likely to deform than conductive particles during lamination. Adhesive extraction water (100 with pure water)
This is a method for producing a multilayer wiring board in which Na and Cl ions (after extraction at 10 ° C. for 10 hours) are each 20 ppm or less based on the weight of the adhesive.

The configuration of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view illustrating an embodiment of the present invention. Reference numeral 1 denotes an insulating substrate made of phenolic resin, epoxy resin, polyimide, etc., paper, glass cloth, glass nonwoven fabric,
Or the like, which is impregnated into a base material such as polyester, heated and pressed, a plastic film such as polyester or polyimide, a metal such as Al or Fe, and a ceramic. Wiring pattern 2
Although formed on both sides of the insulating substrate 1 as shown in FIG. 1, the outermost layer when a multilayer wiring board is formed may be one side. It is necessary that at least one of the wiring patterns 2 protrudes from the substrate surface as shown in FIG. The opposing wiring pattern is not shown, but may be any of a flat shape and a concave shape, but it is preferable to protrude from the surface of the insulating substrate 1 from the viewpoint of connection stability. These wiring patterns can be formed by general means such as a tenting method, an additive method, and a transfer method. Insulating substrate 1
An adhesive layer may be present between the wiring pattern 2.

The adhesive layer 7 suitable for the present invention will be described. As the adhesive 6, a thermoplastic material used for a sheet or the like, or a curable material using energy such as heat, light, or an electron beam can be widely applied. Curable materials are preferred because they have excellent heat resistance and moisture resistance of the multilayer wiring board.Epoxy-based adhesives and imide-based adhesives have excellent adhesiveness and heat resistance due to their molecular structure, and can be set over a wide range of curing times. Is preferred. Epoxy adhesives, for example, high molecular weight epoxy,
In general, a solid epoxy, a liquid epoxy, an epoxy modified with urethane, polyester, NBR or the like as a main component, and a curing agent, a catalyst, a coupling agent, a filler, and the like are added. When these materials are high-purity products in which Na ions and Cl ions of the extraction water are 20 ppm or less, it is preferable that the electric corrosion resistance of the multilayer wiring board is improved.

As the conductive particles 5, Au, Ag, Ni,
There are metal particles such as Cu, W, Sb, Sn, and solder, carbon, and the like, and the conductive layer may be formed by coating the conductive layer on a polymer core material such as a non-conductive plastic or the like. Further, the above-mentioned insulating coated particles formed by coating the conductive particles and the insulating layer, and the combination use of the conductive particles and the insulating particles are also extremely useful for thinning the circuit. It is necessary that the particle size of these conductive particles be smaller than the distance between adjacent wiring patterns in order to cope with thinning of wiring. The conductive particles 5 are preferable because they have deformability by heating or pressurizing or pressurizing, and increase the contact area with the circuit at the time of lamination and improve reliability. The term “deformability” refers to a case where the conductive particles are coated particles having a conductive layer on the surface of a polymer core material, or a case where the conductive particles form an aggregate and change the aggregation state during lamination. These particles do not melt like solder and have deformability due to heating and pressing during lamination, so they do not protrude from the wiring pattern or the wiring pattern in which the thickness or flatness varies, or the wiring pattern protrudes. It is easy to cope with the case where the wiring pattern is mixed with the wiring pattern, or the like. The number of conductive particles may be such that the particles have conductivity only in the pressing direction. For this reason, in principle, it is sufficient that only one portion is required on the wiring pattern, but it is preferable to use five or more portions because connection reliability is further improved. When the number of the conductive particles increases, a leak easily occurs between adjacent patterns after lamination and integration.

[0008] The polymer core material of the coated particles having a conductive layer of metal, metal oxide, alloy or the like on the surface of the polymer core material suitable for the present invention includes plastics such as polystyrene and epoxy resin, rubbers and the like. Polymers. The conductive particles having a conductive layer on the surface of the polymer nucleus material do not show a melting point unlike solder, so that the softened state can be widely controlled by the connection temperature. In the case of coated particles or hard metal particles such as Ni and W, reliability is improved by forming an aggregate and changing the aggregate state during lamination.

At the time of lamination and integration, an adhesive layer made of conductive particles and an adhesive is formed between a plurality of double-sided wiring boards having at least a wiring pattern protruding on an insulating substrate, and the wiring pattern surface is formed. The parts requiring connection are aligned and laminated by heating and pressing. At this time, a so-called pin lamination method in which, for example, a through-hole is formed in a predetermined number of wiring boards that require lamination and alignment is performed with pins or the like is preferable. As a method of integration, a general method such as pressing or a roll laminator is used. Good way. Filling the through-hole of the pin lamination method with a conductive adhesive,
Electrical connection between all layers can be obtained by plating through holes.

FIG. 2 is a schematic sectional view showing the structure of FIG. 1 after lamination and integration. An adhesive layer 7 made of conductive particles 5 and an adhesive 6 is laminated and integrated between the first and second wiring boards 3 and 4 having the wiring pattern 2 requiring connection.
The two wiring boards 3-4 are bonded together, and electrical connection between the wiring patterns 2-2 'which requires these connections is obtained. Wiring pattern 2 which needs connection here
May be an entire pattern or a part of the pattern, and a connection-free wiring pattern 8 (for example, a via hole) may be present on the connection surface. In the case of the deformable particles, which are preferable conductive particles, the conductive particles 5 are deformed into the portion 2-2 'that requires connection on the wiring pattern, so that the contact area with the pattern is increased, the connection resistance is stabilized, and the reliability is improved. Also improve.

By arbitrarily laminating this layer, an arbitrary multilayer wiring board can be obtained. Although the optimum filling amount of the adhesive can be controlled by the thickness of the adhesive, it is preferable that the unnecessary portion is removed by flowing out to the end by laminating and integrating, so that air bubbles are less mixed. This situation will be described with reference to FIG. The degree of deformation is changed according to the difference in height (2, 2A) of the protruding wiring pattern, and FIG. 3 is deformed by thermal deformation of the core material of the coated conductive particles. At this time, if at least a hard granular material 9 that is at least equal to the distance of the opposing wiring pattern after lamination and integration and is less likely to be deformed than the conductive particles at the time of lamination is contained, the conductivity according to the difference in the height of the wiring pattern is increased. This is preferable because the degree of deformation of the particles can be easily controlled. The granular material 9 may use the single particle size of hard conductive particles as they are, and may be insulating silica, glass, hard resin such as henzoguanamine, or the like.

FIG. 4 shows an example of a sectional structure of a multilayer wiring board obtained by the present invention. Wiring pattern 11 with protruding wiring pattern
And the wiring pattern 12 that does not protrude are mixed, but a portion including the protruding wiring pattern that requires connection of the wiring pattern including the through-hole portion 13 is interlayer-connected,
Wiring patterns that do not protrude, for example, wiring patterns that do not protrude on a flat surface or a concave surface, are insulated and connected between layers.

[0013] According to the present invention, the bonding between conductive particles having a particle size smaller than the distance between adjacent wiring patterns and an adhesive is provided between two or more double-sided wiring boards having wiring patterns protruding from the insulating substrate. Since it is a multi-layered wiring board with an agent layer arranged and laminated and integrated by heating and pressing, a cover film is unnecessary because it is in contact with the insulating adhesive except for the interconnecting parts,
Since the interconnects are electrically connected only by the pressure in the pressing direction by conductive particles, no plating is required. The conductive particles have deformability due to heating and pressurizing or pressurizing but do not melt, so they can cope with variations in the height of the wiring pattern, connect the desired wiring pattern, and increase the contact area with the circuit at the time of lamination and increase reliability. The performance is improved. In addition to controlling the concentration of the conductive particles, no leak occurs between the patterns, and the conditions of thermocompression bonding can be applied in a wide range. Therefore, the connection resistance is stabilized, the reliability is improved, and it is possible to cope with the thinning of the circuit. In addition, a multilayer wiring board which is effective in reducing the thickness and cost of the multilayer wiring board can be obtained very easily.

[0014]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition, for simplicity of description, a four-layer wiring board in which two double-sided boards are connected to each other will be described. However, one of the two double-sided boards may be a single-sided board, and a multilayer wiring board having more than four layers may be used. Applicable.

Examples 1 to 3 Adhesive 10 was applied to both sides of a polyimide film having a thickness of 50 μm.
A double-sided board formed by forming a copper foil 18 μm through
A wiring board on which pattern printing, etching, and the like were performed was prepared. The minimum diameter of the wiring pattern that requires connection is 50 μm
Met. Polytetrafluoroethylene film 25μ
m, thickness of 30 μm mainly composed of high molecular weight epoxy
Adhesive (Na of extraction water after extraction with pure water at 100 ° C for 10h)
Ions and Cl ions are each 10 ppm or less). The following conductive particles were uniformly dispersed in the adhesive at 2% by volume to obtain an adhesive film. The conductive particles used here were Ni / Ni particles on the surface of a core material made of cross-linked polystyrene.
As in Example 1, a plated plastic sphere having a composite conductive layer of Au and having a particle diameter of 10 μm (Example 1), a combination of the particles of Example 1 and 1% by volume of silica particles having a particle diameter of 3 μm (Example 2). Are insulating coated particles (Example 3) obtained by coating the surface of a plated plastic sphere having a particle diameter of 3 μm with nylon having a thickness of about 0.2 μm. Place an adhesive film on a wiring pattern of the wiring board that requires one connection,
After passing between the rubber rolls, the polytetrafluoroethylene film is peeled off, aligned with a wiring pattern requiring connection of another wiring board, and then filled with a through-hole portion with a conductive adhesive at 180 ° C. and 20 kg. / Cm ² for 30 minutes to cure the adhesive. As described above, a four-layer wiring board in which two double-sided boards are connected between layers is obtained. Examples 1-3
All showed sufficient interlayer connection characteristics. In Example 1, the plated plastic ball was appropriately deformed, and the distance between the minimum portions of the opposed wiring patterns was controlled to 2 μm. Example 2
In Example 1, the distance between the minimum portions of the opposing wiring patterns was 3 μm, and the distance was controlled by the particle size of the silica particles. Example 3 was agglomerated because of its small particle size, but conductivity was obtained only in the pressing direction.

Example 4 Adhesive 1 was applied to both sides of a glass epoxy substrate having a thickness of 0.2 mm.
A wiring board was prepared by performing pattern printing, etching, and the like on a double-sided board formed with a copper foil of 18 μm through 0 μm. The minimum diameter of the wiring pattern that requires connection is 20
μm. Using the adhesive film of Example 1, the same positioning, heating, pressurizing, and curing of the adhesive as in Example 1 were performed to obtain a four-layer wiring board in which two double-sided boards were interconnected.
Example 4 also showed sufficient interlayer connection characteristics.

[0017]

As described above, according to the present invention, it is possible to cope with the variation in the height of the wiring pattern, to connect a desired wiring pattern, and to eliminate the need for a cover film or a plating step and to cope with thinning of the wiring. A multilayer wiring board using a possible interlayer connection can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the configuration of the present invention.

FIG. 2 is a schematic sectional view showing one embodiment of the present invention after lamination and integration.

FIG. 3 is a schematic sectional view showing one embodiment of a deformed state of the conductive particles of the present invention.

FIG. 4 is a schematic sectional view showing one embodiment of the multilayer wiring board of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating board 2 Wiring pattern 3 First wiring board 4 Second wiring board 5 Conductive particles 6 Adhesive 7 Adhesive layer 8 Connection unnecessary wiring pattern 9 Granular object 11 Projected wiring pattern 12 Non-projected wiring pattern 13 Through Hall

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Naoyuki Shiozawa 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. (72) Inventor Yutaka Yamaguchi 1500 Ogawa, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.F-term (reference) 4J040 EC001 EH031 HA066 KA32 NA19 5E344 AA01 AA22 BB02 BB06 CD02 DD06 EE21 EE23 5E346 AA12 AA15 AA16 AA22 AA32 AA35 AA51 CC42 EE06 EE07 EE12 EE18 GG28 HH26 HH31

Claims (4)

[Claims] A conductive material having a particle size smaller than a distance between adjacent wiring patterns and an adhesive is provided between two or more double-sided wiring boards each having a protruding wiring pattern formed on an insulating substrate. Is a method for producing a multilayer wiring board in which an adhesive layer having a layer is disposed and laminated and integrated by heating and pressing to perform interlayer connection, in which conductive particles are formed on the surface of a polymer core. Manufacturing method of multilayer wiring board. 2. The method for manufacturing a multilayer wiring board according to claim 1, wherein five or more conductive particles are present in a portion of the interlayer connection requiring connection on the wiring pattern. 3. The method according to claim 1, wherein the adhesive layer further contains hard particles which are at least equal to the distance between the opposing wiring patterns after lamination and integration and are less likely to deform than conductive particles during lamination. The method for manufacturing a multilayer wiring board according to claim 1 or 2, wherein 4. Extraction water of an adhesive (pure water at 100 ° C., 10
The method for producing a multilayer wiring board according to any one of claims 1 to 3, wherein Na and Cl ions after time extraction) are each 20 ppm or less based on the weight of the adhesive.