JP2002363386A - Resin composition for filling hole of printed wiring substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for filling holes of a printed wiring substrate which is a thermosetting resin composition for filling holes such as via holes and through holes formed in a printed wiring substrate such as a multi-layered substrate and a double-sided substrate and can impact high heat resistance and, simultaneously, can control the expansion by heat to its lower level. SOLUTION: The resin composition for filling holes of a printed wiring substrate comprises an epoxy resin which is liquid at room temperature, a curing catalyst, and a filler, and as the above epoxy resin, a glycidylamine type epoxy resin is incorporated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin composition for filling holes such as via holes or through holes formed in a printed wiring board such as a multilayer board or a double-sided board.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high performance of electronic equipment, the pattern of a printed wiring board has become finer and the mounting area has been reduced. For this reason, multilayer printed wiring boards on which wiring can be laminated have been favorably used as printed wiring boards.

In a multilayer printed wiring board, through holes and via holes are formed in a core substrate to electrically connect layers of a conductor circuit. Since another layer is laminated on such a through hole or via hole, its surface needs to be flat. Therefore, generally, holes such as through holes and via holes are filled with resin to flatten the surface, and then another layer is stacked thereon.

[0004] By the way, solder is used for surface mounting components on a printed wiring board.
Lead-free solder tends to be used due to environmental problems. Lead-free solder is better than traditional lead-containing solder
Since the bonding temperature at the time of mounting becomes higher, the multilayer printed wiring board is required to have heat resistance that can withstand higher temperatures than before. For this reason, as a core substrate used for a multilayer printed wiring board, glass-BT (bismaleimide /
High heat-resistant laminates such as triazine resin) composite substrates and high Tg glass-epoxy composite substrates (FR-4, FR-5, etc.) are preferably used. In addition, high heat resistance is also required for a double-sided board due to an increase in mounting and joining temperature due to the use of lead-free solder.

[0005] High heat resistance is also required for filling resins used for filling the above-mentioned via holes and through holes. If the filling resin filled in via holes and through holes expands due to heat, cracks will occur in the insulating layer and solder resist layer laminated on these, so there is a need for a filling resin with small expansion due to heat. I have. As the filling resin for the printed wiring board, a thermosetting epoxy resin and an ultraviolet / heat combined curing epoxy resin are generally used.

[0006] By increasing the glass transition temperature (Tg) of the filling resin, the temperature range of the rubbery region above the glass transition temperature is reduced, so that expansion at high temperatures can be suppressed. From such a viewpoint, it is conceivable to increase the curing temperature of the filling resin or lengthen the curing time to increase the Tg of the filling resin to suppress thermal expansion. JP-A-10-75027, JP-A-10-75027
Japanese Patent Application Laid-Open No. 2203404 and Japanese Patent Application Laid-Open No. 11-140280 disclose raising the glass transition temperature of the filling resin by curing at a high temperature or for a long time.

[0007]

However, when the curing temperature is increased, shrinkage from curing to cooling increases,
There is a problem that the substrate is warped. Further, if the curing time is lengthened, there is a problem that the productivity is deteriorated because the manufacturing process is lengthened.

An object of the present invention is to increase the curing temperature,
Another object of the present invention is to provide a resin composition for filling holes in a printed wiring board, which can increase the glass transition temperature and suppress thermal expansion without lengthening the curing time.

[0009]

The resin composition for filling holes according to the present invention is a thermosetting resin composition for filling holes formed in a printed wiring board, and comprises an epoxy resin which is liquid at room temperature and a curing catalyst. And a filler, and a glycidylamine type epoxy resin as an epoxy resin.

In the present invention, since a glycidylamine type epoxy resin is contained as an epoxy resin,
Without increasing the curing temperature or prolonging the curing time,
Glass transition temperature can be increased. For this reason, thermal expansion can be suppressed, and heating by soldering etc.
Cracks and the like can be prevented from occurring in the insulating layer and the solder resist layer formed thereon.

In the present invention, since an epoxy resin which is liquid at room temperature is used, it can be used without being diluted with a solvent. Accordingly, the solvent is not volatilized during the curing after filling into the via hole or the through hole or the like, so that the hole such as the via hole or the through hole can be filled in a good condition.

Hereinafter, each component of the resin composition for filling holes of the present invention will be described. <Glycidylamine-type epoxy resin> The glycidylamine-type epoxy resin is an epoxy resin obtained by reacting epichlorohydrin with active hydrogen of an amine compound.
As the glycidylamine type epoxy resin used in the present invention, those which are liquid at room temperature are preferably used. In the present invention, “liquid at room temperature” means that the composition is liquid at the time of preparation and use, and room temperature generally means a temperature range of about 0 ° C. to about 30 ° C. I have.

Specific examples of the glycidylamine type epoxy resin include, for example, tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, diglycidylaniline, diglycidyltoluidine, tetraglycidyl metaxylenediamine, tetraglycidylbisaminomethylcyclohexane and the like. No. Among them, epoxy resins having three or more epoxy groups in one molecule are preferable, and such resins include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, tetraglycidylmethaxylenediamine, and tetraglycidylbisaminomethylcyclohexane. No.

<Other Epoxy Resins> In the present invention, another epoxy resin may be mixed with the glycidylamine type epoxy resin. As the other epoxy resin, a liquid at room temperature is preferably used. Specific examples of other epoxy resins include bisphenol A
Type, bisphenol F type phenol novolak type, cresol novolak type epoxy resin, etc., and these resins can be used alone or in combination of two or more.

Further, for the purpose of lowering the viscosity,
Aliphatic polyfunctional epoxy resins such as 1,6 hexanediol diglycidyl ether, neopentyl diglycidyl ether, and polypropylene glycol diglycidyl ether; monofunctional aromatic epoxy resins such as phenyl glycidyl ether and cresyl glycidyl ether; and butyl glycidyl ether And other monofunctional aliphatic epoxy resins.

When the above aliphatic polyfunctional epoxy resin, monofunctional aromatic epoxy resin and monofunctional aliphatic epoxy resin are mixed with a glycidylamine type epoxy resin, the epoxy resin has low reactivity and glass transition. Since the temperature is lowered and unreacted components may remain, the mixing ratio is preferably 1 to 30% by weight, more preferably 1 to 20% by weight, based on the total epoxy resin.
% By weight.

The mixing ratio of the glycidylamine type epoxy resin is preferably at least 2% by weight, more preferably at least 10% by weight in all epoxy resins. If the blending ratio of the glycidylamine type epoxy resin is low, the glass transition temperature cannot be increased, and the thermal expansion may not be sufficiently suppressed.

<Curing Catalyst> The curing catalyst is not particularly limited as long as it can cure the epoxy resin, but imidazole is particularly preferably used because of its excellent chemical resistance and hygroscopicity. Can be Specific examples of imidazole include trade names (all trade names are manufactured by Shikoku Chemicals Corporation) “2MZ”, “C11Z”, “C1
Imidazoles such as "7Z" and "2E4MZ";
AZI of imidazole such as "-A" and "2E4MZ-A"
NEs, imidazole isocyanurate such as "2MA-OK", "2PZ-OK", "2PHZ", "2P4"
MHZ ”and the like.

In the present invention, the curing catalyst is preferably blended in an amount of 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, based on 100 parts by weight of the epoxy resin. If the amount is too small, curing may be insufficient, the glass transition temperature may be lowered, and sufficient heat resistance may not be obtained. If the amount is too large, the reactivity may increase, and a problem may occur in storage stability.

<Filler> The filler used in the present invention includes a metal filler, an inorganic filler and a resin filler. Copper, as metal filler
Fillers such as silver and aluminum are exemplified, and examples of the inorganic filler include fillers such as silica, precipitated barium sulfate, talc, alumina, zirconia, and calcium carbonate. Examples of the resin filler include resin fillers such as an acrylic polymer and a styrene polymer. Further, a halogen-based organic substance, a phosphorus-based organic substance, or the like may be blended as a filler for imparting flame retardancy. The fillers described above may be used alone or in combination of two or more.

The average particle size of the filler is 0.1 to 15 μm.
m is preferable. If the thickness is less than 0.1 μm, the viscosity of the resin composition becomes too high, so that the filling workability may be deteriorated. On the other hand, if it is larger than 15 μm, the smoothness of the surface of the filled portion filling the hole may be deteriorated.

The compounding ratio of the filler is appropriately set within a range that does not impair the workability of filling the resin composition into the holes. In the present invention, whiskers may be contained as a filler. By including whiskers as fillers, thermal expansion can be further suppressed.

As the whiskers, those generally defined as whiskers can be used. In general,
The whisker has a cross section of 8 × 10 ⁻⁵ in ² (5.16 ×
10 ^{- 2} mm ²⁾ or less in length than the average diameter of the cross-section 1
It is defined as "0 times or more single crystal."

The whiskers used in the present invention include:
Those having an average fiber length of 2 to 30 μm are preferably used. Specific examples of whiskers include aluminum borate, potassium titanate, silicon carbide, silicon nitride, magnesium borate, zinc oxide, graphite, and the like. These whiskers may be used alone or in combination.

It is preferable to use whiskers that have been surface-treated with a coupling agent such as a silane coupling agent. The surface treatment enhances the wettability to the epoxy resin, so that even if it is blended in a large amount, the viscosity does not increase, and the workability of filling holes is improved.

The mixing ratio of the whiskers is 10
It is preferably at least 1 part by weight with respect to 0 parts by weight,
More preferably, the amount is 5 parts by weight or more. If the mixing ratio is small, the effect of suppressing thermal expansion may not be sufficiently obtained. The upper limit of the compounding ratio varies depending on the epoxy resin used because the compounding can be performed until the viscosity does not impair the workability of filling the holes. Generally,
80 parts by weight or less is suitable for 100 parts by weight of the epoxy resin. Accordingly, a preferable range of the mixing ratio of the whisker is 1 to 80 parts by weight based on 100 parts by weight of the epoxy resin.

In the resin composition for filling holes of the present invention,
In addition to the above components, additives such as an antifoaming agent, a leveling agent, and a thixotropic agent can be blended within a range that does not impair the performance.

The resin composition for filling holes of the present invention can be filled into holes such as via holes and through holes of a printed wiring board by conventional screen printing or the like. After filling the holes, usually 90-150 ° C
For about 30 to 60 minutes for primary curing. 1
At the time of the completion of the next curing, the substrate has not been completely cured, and thus the portion of the substrate surface that protrudes from the hole can be physically polished and removed to flatten the substrate surface. Then, heat at 140-150 ° C for about 30-60 minutes to
Next curing (final curing) can be performed.

The resin composition for filling holes of the present invention can be used as a resin composition for filling permanent holes for filling holes such as via holes and through holes formed in a printed wiring board. After curing, a resin composition having low thermal expansion and excellent heat resistance can be obtained.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples, and may be appropriately changed within the scope of the gist. It can be implemented by

(Examples 1 to 5 and Comparative Example 1) The following epoxy resin, curing catalyst, silica, whisker, and fumed silica were used as the compounding components, and each compounding ratio (parts by weight) shown in Table 1 was used. After the components were preliminarily mixed, they were kneaded and dispersed by three rolls to prepare a resin composition.

Glycidylamine type epoxy resin: tetraglycidyl meta-xylylenediamine, trade name "TET"
RAD X ", manufactured by Mitsubishi Gas Chemical Company, epoxy equivalent = 10
3. Bisphenol F type epoxy resin: trade name “Epicoat YDF-807”, manufactured by Japan Epoxy Resin Co., epoxy equivalent = 170 Curing catalyst: imidazole curing catalyst, trade name “Curesol 2MZ-A”, manufactured by Shikoku Chemicals Co., Ltd. Silica: trade name "Crystalite WX", manufactured by Tatsumori Co., Ltd.-Aluminum borate whisker: trade name "Albolex YS3C", manufactured by Shikoku Chemicals, Inc., average fiber length 10 m-Fumed silica: trade name "AEROSIL R-8"
12 ", manufactured by Nippon Aerosil Co., Ltd.

[0033]

[Table 1]

With respect to the resin compositions of Examples 1 to 5 and Comparative Example 1 obtained as described above, the glass transition temperature and the coefficient of linear expansion were measured as follows. Glass transition temperature: The resin compositions of Examples 1 to 5 and Comparative Example 1 were applied to a fluororesin plate which had been washed and dried in advance with a doctor blade (30 mil), and dried in a hot-air circulation drying oven for 150 minutes. After curing for 1 hour at 150C, after cooling, post-curing was performed at 150C for 30 minutes. After cooling to room temperature, the cured coating film was peeled off from the fluororesin plate to obtain an evaluation sample. Using this evaluation sample, TMA
The glass transition temperature was measured by the method.

Linear expansion coefficients (α1 and α2): Using the same evaluation samples as above, the linear expansion coefficient α1 before the glass transition temperature and the linear expansion coefficient α2 after the glass transition temperature were measured by the TMA method.

Linear expansion coefficient (30 to 280 ° C.): The linear expansion coefficient in the temperature range of 30 to 280 ° C. was measured by the TMA method using the evaluation sample. Table 2 shows the measurement results. In addition, each of the above linear expansion coefficients is
It has the relationship shown in FIG. As is clear from FIG. 1, the linear expansion coefficient α1 before the glass transition temperature (Tg) and the linear expansion coefficient α2 after the glass transition temperature (Tg) are reduced, so that the linear expansion coefficient in the temperature range of 30 to 280 ° C. α decreases. Also, as shown by the dashed line, the linear expansion coefficient α
It can be seen that, even when the coefficient of linear expansion 1 and the coefficient of linear expansion α2 are the same, the linear expansion coefficient α at 30 to 280 ° C. decreases with an increase in Tg.

[0037]

[Table 2]

As is clear from the results shown in Table 2, the resin compositions of Examples 1 to 5 containing the glycidylamine type epoxy resin had a smaller linear expansion coefficient than the resin composition of Comparative Example 1. You can see that there is. Further, it can be seen that the glass transition temperature increases as the content of the glycidylamine type epoxy resin increases. Due to the increase in the glass transition temperature, as described with reference to FIG.
The linear expansion coefficient α at 280 ° C. is small.

As is evident from the results of Example 5, by containing aluminum borate whiskers as the filler, the coefficient of linear expansion is further reduced, and the thermal expansion is suppressed.

As described above, the resin compositions of Examples 1 to 5 have a small thermal expansion and are suitable as a resin composition for filling permanent holes in a printed wiring board.

[0041]

The resin composition for filling holes according to the present invention has a low linear expansion coefficient, and can reduce expansion due to heat. Therefore, when used as a resin composition for filling permanent holes in a printed wiring board, expansion due to heat can be reduced even at a high temperature such as stagnant reflow.
Therefore, by using the resin composition for filling holes of the present invention, work of filling holes such as via holes and through holes of a printed wiring board can be performed efficiently, and a highly reliable printed wiring board can be manufactured with high productivity. Will be able to do it.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a relationship between a linear expansion coefficient α1 before a glass transition temperature and a linear expansion coefficient α2 after a glass transition temperature, and a linear expansion coefficient α in a temperature range of 30 to 280 ° C.

Continued on the front page (72) Inventor Takahiro Nakano 19-17 Ikedanakamachi, Neyagawa-shi, Osaka F-term in Nippon Paint Co., Ltd. (reference) 4J002 BC022 BG032 CD131 DA027 DA077 DA097 DE097 DE107 DE147 DE187 DE237 DG047 DJ007 DJ017 DJ047 DK007 EU116 FA067 FA082 FA087 FB097 FD012 FD017 FD156 GQ05 4J036 AH07 AH18 AH20 DA02 DC40 FA01 FB01 JA08 5E314 AA25 AA32 AA41 AA42 AA43 BB06 FF05 FF08 GG24

Claims (5)

[Claims] 1. A thermosetting resin composition for filling a hole formed in a printed wiring board, comprising a liquid epoxy resin at room temperature, a curing catalyst, and a filler, wherein glycidylamine is used as the epoxy resin. A resin composition for filling holes in a printed wiring board, comprising a mold epoxy resin. 2. The resin composition for filling holes in a printed wiring board according to claim 1, wherein the glycidylamine type epoxy resin is a resin having three or more epoxy groups in one molecule. 3. The resin composition for filling holes in a printed wiring board according to claim 1, wherein the curing catalyst is imidazole. 4. The resin for filling holes in a printed wiring board according to claim 1, wherein the filler is at least one selected from a metal filler, an inorganic filler, and a resin filler. Composition. 5. The resin composition for filling holes in printed wiring boards according to claim 1, wherein whiskers are contained as the filler.