JPH11181398A - Adhesive composition, multilayer printed circuit board prepared by using the same, and production of multilayer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive compsn. which has an easily controllable flowability by incorporating a thermosetting resin, an elastomer of which part of the structural units of the main chain have been crosslinked, and an inorg. filler into the same. SOLUTION: This compsn. contains, as essential ingredients, 100 pts.wt. thermosetting resin, 1-20 pts.wt. elastomer (e.g. an acrylonitrile-butadiene copolymer elastomer) having a particle size of from 10 nm to 2 mm and having a main chain of which part of the structural units have been crosslinked, and 10-50 pts.wt. inorg. filler having a particle size of 0.02-200 μm and selected from among alumina, titanium oxide, etc. The compsn. is dissolved or dispersed in a solvent (e.g. methyl ethyl ketone, methyl glycol, dimethylformamide, or their mixture), then applied as a varnish to a substrate, and dried and pressed under heating to give a multilayer printed circuit board. The thermosetting resin is at least two resins selected from among benzoxazine-ring-contg. resins, epoxy resins, polyimide resins, etc., and is used together with a curing agent and/or a cure accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition, a multilayer printed wiring board using the adhesive composition, and a method for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art A multilayer printed wiring board is manufactured by bonding and integrating a plurality of substrates, and a substrate is bonded to a thermosetting resin composition containing a thermosetting resin such as an epoxy resin using a glass cloth or the like. A prepreg obtained by impregnating and drying a material is used. The thermosetting resin composition impregnated and dried in the prepreg is once melted and fluidized in a pressing step at the time of bonding and integration, so as to fill the recesses between the conductor circuits formed on the substrate. Recently, packages (hereinafter simply referred to as packages) used for mounting semiconductor elements, such as chip carriers, pin grid arrays, and ball grid arrays, have been manufactured by a method of manufacturing a multilayer printed wiring board. For example, as shown in FIG. 1, the pin grid array includes a lower substrate 2a having a semiconductor element mounting portion 1 and upper substrates 2b, 2c having window holes 4b, 4c, and 4d serving as cavities 3 for accommodating semiconductor elements.
This is a multilayer printed wiring board in which c and 2d are bonded and integrated, and electrical connection and mounting conductor pins 5 are inserted through them. One of the upper substrates, for example, 2b, is usually provided with a bonding pad 6 for bonding a wire from a semiconductor element.
d, except for the surface of the lower substrate 2a and the upper substrates 2b and 2c.
Is provided with a conductor circuit 7. Although FIG. 1 shows an example in which the number of the upper substrates is three, the number of the upper substrates is not limited to this.

As described above, the upper substrates 2b, 2
When prepregs similar to those used in the production of a conventional multilayer printed wiring board are used when adhesively integrating c and 2d, the thermosetting resin composition once melted and fluidized in the pressing step becomes Figure 2
As shown in FIG. 7, the bonding pad 6 was sometimes covered with the protruding thermosetting resin composition. It is not preferable that the bonding pad 6 is covered with the protruding thermosetting resin composition because it becomes difficult to bond a wire from a semiconductor element. Therefore, a prepreg has been developed in which the curing of the thermosetting resin composition is advanced more than the prepreg used in the production of ordinary multilayer printed wiring boards, and the resin flow during press molding is reduced.

[0004]

However, since the curing conditions of the thermosetting resin composition vary depending on the resin composition and the type and amount of the solvent, it is difficult to properly adjust the resin flow. In prepregs in which the resin flow at the time of press molding is reduced, voids remain because the resin flow may be small and the dents between the conductor circuits may not be sufficiently filled, and the thermosetting resin is further hardened. Therefore, there is a disadvantage that the adhesion to the substrate is also deteriorated.

The present invention has been made in view of the above situation, and has an adhesive composition which can easily adjust a resin flow.
By using this adhesive composition, a multilayer printed wiring board with small protrusion of resin into the cavity, and
It is an object of the present invention to provide a manufacturing method thereof.

[0006]

The invention according to claim 1 is an adhesive composition containing a thermosetting resin, an elastomer in which a part of a main chain structural unit is crosslinked, and an inorganic filler as essential components. .

[0007] According to a second aspect of the present invention, there is provided a multilayer printed wiring board using the adhesive composition of the first aspect for bonding between substrates.

[0008] The elastomer and the inorganic filler in which a part of the structural unit of the main chain is crosslinked are dispersed as particles in the thermosetting resin without melting at the time of press molding, so that a so-called sea-island type dispersed structure can be obtained. The protrusion of the resin into the cavity can be suppressed by suppressing the flow of the melted thermosetting resin by the particles scattered in the thermosetting resin. Since the flowability of the melted thermosetting resin can be adjusted by the amount of the elastomer and inorganic filler in which a part of the main chain structural unit blended in the thermosetting resin is cross-linked, the control is also easy and constant. Quality. And since it is not necessary to advance the curing of the thermosetting resin, the adhesiveness to the substrate is not impaired. It is necessary to use an elastomer and an inorganic filler in which a part of the main chain structural unit is crosslinked. When an elastomer in which a part of the main chain structural units is crosslinked alone is used, the heat resistance of the obtained multilayer printed wiring board is reduced. Also,
When the inorganic filler is used alone, the flexibility is reduced and cracks occur during processing such as drilling.

The adhesive composition according to the first aspect of the present invention has a small resin flow during heat curing. Thus forming the adhesive composition having a small resin flow into a sheet,
If this is inserted between the substrates and heated and pressed, the recesses between the conductor circuits formed on the substrate surface may not be sufficiently filled. Therefore, it is preferable to dissolve and disperse the adhesive composition of the present invention in an organic solvent, apply it to the surface of the substrate, dry it, overlay another substrate thereon, and apply heat and pressure. That is, a third aspect of the present invention is a multilayer printed wiring, wherein the adhesive composition according to the first aspect is used as a varnish, the varnish is applied to an adhesive surface of a substrate, dried, and then heated and pressed. This is a method for manufacturing a plate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermosetting resin used in the adhesive composition of the present invention includes a resin having a benzoxazine ring in its structure, an epoxy resin, a polyimide resin,
Examples include isocyanate resins, resins having a triazine ring in the structure, phenol resins, unsaturated polyester resins, and the like. Two or more of these thermosetting resins can be used in appropriate combination. These thermosetting resins include:
A necessary curing agent and / or curing accelerator is used. As the curing agent and / or curing accelerator, a known curing agent and / or curing accelerator for each thermosetting resin can be used, There is no particular limitation.

The elastomer used in the present invention in which a part of the main chain structural unit is cross-linked may be obtained by cross-linking a part of the main chain structural unit of an elastomer such as polyurethane, acrylic, polyamide or vinyl acetate. Elastomers. Among them, an acrylonitrile-butadiene copolymer elastomer is preferably used because it easily forms a sea-island structure with a thermosetting resin and has excellent heat resistance when absorbing moisture. From the viewpoint of dispersibility in the thermosetting resin, the particle size of the elastomer is 1
It is preferably from 0 nm to 2 mm, more preferably from 0.5 to 2 μm.

Examples of the inorganic filler used in the present invention include powders of alumina, silica, titanium oxide, zirconia and the like. Among them, alumina powder is preferably used because it has a small amount of impurities and is excellent in electric insulation or corrosion resistance. The particle size of the inorganic filler is
From the viewpoint of dispersibility in a thermosetting resin, 0.02 μm to 2
It is preferably 00 μm, more preferably 0.05 to 100 μm.

The mixing ratio of the thermosetting resin, the elastomer in which a part of the main chain structural unit is crosslinked, and the inorganic filler is such that a part of the main chain structural unit is crosslinked with respect to 100 parts by weight of the thermosetting resin. It is preferred that the elastomer be 1 to 20 parts by weight and the inorganic filler be 10 to 50 parts by weight. When the elastomer in which a part of the main chain structural units is crosslinked is less than 1 part by weight and the inorganic filler is less than 10 parts by weight, the effect of reducing the protrusion of the resin is reduced. When the crosslinked elastomer exceeds 20 parts by weight and the inorganic filler exceeds 50 parts by weight, the amount of the thermosetting resin becomes relatively small, and the phase of the thermosetting resin becomes discontinuous. It tends to be inferior. For this reason, the elastomer in which a part of the structural unit of the main chain was cross-linked was 100 parts by weight of the thermosetting resin.
More preferably, the content of the inorganic filler is set to 20 to 40 parts by weight.

The adhesive composition of the present invention is preferably used by dissolving and dispersing it in an organic solvent and applying it to a substrate as a varnish. Examples of the organic solvent used herein include methyl ethyl ketone, methyl glycol and methyl glycol. Examples include isobutyl ketone, methyl cellosolve, butyl cellosolve, dimethylformamide, dimethylacetamide, acetone, toluene, methanol, and the like, and these are used alone or in appropriate combination of two or more kinds. The mixing ratio of the adhesive composition and these organic solvents is selected according to the workability when applying the composition to a substrate as a varnish. Drying after applying the varnish is preferably touch drying, since good adhesion can be formed.

Although the description has been given mainly of the multilayer printed wiring board having a cavity for mounting a semiconductor, the adhesive composition of the present invention and the manufacturing method of the present invention are applied to a conventional multilayer printed wiring board having no cavity. It goes without saying that it can be applied to manufacturing.

[0016]

Example 1 80 parts by weight of a thermosetting resin having a benzoxazine ring in its structure (HR-1000 (trade name) manufactured by Hitachi Chemical Co., Ltd.), bisphenol A type brominated epoxy resin ( Epoxy equivalent 40, bromine content 48% by weight) 2
0 parts by weight, 5 parts by weight of a crosslinked acrylonitrile-butadiene copolymer elastomer (acrylonitrile content: 20% by weight, manufactured by Nippon Synthetic Rubber Co., Ltd., XER-91 (trade name)) and 10 parts by weight of aluminum hydroxide The adhesive composition was mixed with a mixed solvent of methyl ethyl ketone and dimethylformamide in the same amount (weight ratio) with a viscosity of 25P.
An adhesive varnish was prepared by dissolving and dispersing so as to obtain a · s.

A conductor circuit was formed on a single-sided copper-clad laminate having a size of 500 × 300 mm, a thickness of 0.2 mm, and a thickness of copper of 12 μm, thereby forming a lower substrate. Also, 500 × 300 mm, thickness of 0.1 mm.
A conductor circuit and a 15 × 15 mm window hole were formed in a single-sided copper-clad laminate having a thickness of 1 mm and a copper foil thickness of 12 μm to form an upper substrate.
Next, by masking the position of the window hole when the upper substrate is overlaid on the lower substrate, by printing the adhesive varnish prepared above,
The thickness measured from the board surface excluding the conductor circuit is 50 μm
Then, apply so that the unevenness of the conductor circuit does not appear on the surface,
Thereafter, the mixture was heated at 80 ° C. for 30 minutes to evaporate the solvent, thereby forming an adhesive layer. An upper substrate was overlaid on the adhesive layer, and heated and pressed at a temperature of 175 ° C. and a pressure of 3.0 MPa to produce a multilayer printed wiring board.

Example 2 45 parts by weight of a thermosetting polyimide resin (Kerimide 601 (trade name) manufactured by Rhone Poulin Co., France), a phenol novolak type epoxy resin (Epicoat 154 (trade name) manufactured by Yuka Shell Epoxy Co., Ltd.) First name)
45 parts by weight, dicyandiamide 10 parts by weight, crosslinked acrylonitrile-butadiene copolymer elastomer (X
An adhesive varnish was prepared by dissolving and dispersing an adhesive composition comprising 5 parts by weight (using ER-91) and 10 parts by weight of aluminum hydroxide in dimethylacetamide so as to have a viscosity of 25 Pa · s. Example 1 below
A multilayer printed wiring board was produced in the same manner as described above.

Comparative Example 1 An adhesive varnish was prepared in the same manner as in Example 1 except that the crosslinked acrylonitrile-butadiene copolymer elastomer was removed, and a multilayer printed wiring board was produced.

Comparative Example 2 An adhesive varnish was prepared in the same manner as in Example 2 except that the crosslinked acrylonitrile-butadiene copolymer elastomer was removed, and a multilayer printed wiring board was produced.

The adhesive varnishes prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were desolvated under vacuum,
Heated for a minute to cure. About the obtained cured product,
The glass transition point (Tg) was examined by the TMA method specified in ISC 6481, and the heat resistance level was evaluated.

With respect to the multilayer printed wiring boards manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, the length of resin protrusion, the presence or absence of voids, and the peel strength of the bonded portion were examined as follows. Protrusion length of resin: The maximum length of the adhesive protruding from the wall of the opening of the upper substrate was measured by a microsection method. Presence or absence of voids: Observed visually. Peel strength: The load required to peel off the upper and lower substrates and the adhesive layer in the direction of 90 degrees at a clock head speed of 50 mm / min was measured. Table 1 shows the results.

[0023]

[Table 1]

[0024]

According to the first and second aspects of the present invention,
The protrusion of the resin into the cavity can be reduced, and the adhesion between the substrates can be improved. Furthermore, according to the third aspect of the present invention, the adhesive between the conductor circuits is coated with an adhesive, dried and then heated and pressed, so that the depression between the conductor circuits can be sufficiently filled and the bonding without voids can be achieved. A multilayer printed wiring board having good properties can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a pin grid array.

FIG. 2 is a sectional view of a main part when a pin grid array is manufactured by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element mounting part 2a Lower substrate 2b, 2c, 2d Upper substrate 3 Cavity 4b, 4c, 4d Window hole 5 Conductor pin 6 Bonding pad 7 Conductor circuit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Teruki Aizawa 1500, Oji Ogawa, Shimodate City, Ibaraki Prefecture Inside the Shimodate Plant, Hitachi Chemical Co., Ltd. (72) Yasuyuki Hirai 1500 Ogawa Ogawa, Shimodate City, Ibaraki Prefecture Inside the Shimodate Plant (72) Inventor Hideo Nagase 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. An adhesive composition comprising a thermosetting resin, an elastomer in which a structural unit of a main chain is partially crosslinked, and an inorganic filler as essential components. 2. A multilayer printed wiring board using the adhesive composition according to claim 1 for bonding between substrates. 3. A method for producing a multilayer printed wiring board, comprising using the adhesive composition according to claim 1 as a varnish, applying the varnish to an adhesive surface of a substrate, drying and applying heat and pressure.