JP2003077337A - Conductive paste component and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive paste component for printed wiring board interlayer connection, enable to form a bump which does not cause any defective connection with the material having high hardness, crack, or with a wiring pattern. SOLUTION: The adhesive paste component for printed wiring board interlayer connection contains at least one resin chosen from melamine resin, phenol resin, or an epoxy resin, dihydric alcohol and/or trihydric alcohol with boiling point of not less than 180 deg.C, and conductive powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel conductive paste composition, and more particularly to a conductive paste composition used for molding an electronic circuit which requires adhesion to a substrate, hardness and toughness. The present invention relates to an article and a printed wiring board using the same.

[0002]

2. Description of the Related Art Conductive paste compositions are used in various fields such as IC circuits, conductive adhesives and electromagnetic shields in the field of electronics. Particularly recently, a first substrate having a conical conductive bump made of a conductive paste at a predetermined position on at least one surface thereof and a second substrate having a wiring pattern provided on at least one surface thereof. A substrate is made to face each other with the surface on which the conductive bumps are provided and the surface on which the wiring patterns are provided facing each other, and an insulator layer is disposed between the first substrate and the second substrate. There is proposed a method for manufacturing a printed wiring board in which a conductive wiring portion is formed by penetrating the bumps in the thickness direction of the insulating layer by forming a laminated body and laminating and pressing the laminated body. (JP-A-6-350258)

To form the above-mentioned conductive bumps, a binder component such as melamine resin, phenol resin or polyimide resin is mixed with a conductive powder such as silver, gold, copper or solder powder or an alloy powder thereof. The conductive paste composition prepared by the above is used.

[0004]

When the above conductive paste composition is used in the production of the above printed wiring board, there are the following problems.

A first problem is to solve the connection failure due to the penetration failure of the insulating layer for forming the conical bump formed from the conductive paste composition. For this purpose, the height of the conductive bumps needs to be 30 μm or more higher than that of various insulating layers, and the average height of the bumps must be 180 μm or more. Further, 3σ at this time is required to be 25 μm or less. 3σ includes 99.74% of ± 3σ centered on the average value of the bump height.

Further, the penetration temperature of the conductive bump must be set in an optimum range depending on various insulating layers.
For example, FR-4 having a relatively low softening point (US NEMA: n
national electrical manufa
The prepreg containing glass cloth according to the Cturers association standard) penetrates in a temperature range of 80 to 120 ° C. Therefore, the bump softening point and hardness are required to prevent deformation in this temperature range. If it is deformed, the bump cannot penetrate the insulator layer, resulting in a poor connection between the layers.

A third problem is to solve the connection failure due to the breakage of the bump during the penetration and the laminating press, and the short circuit of the circuit due to the jump of the tip of the bump. this is,
When the binder resin was brittle, it tended to occur when the filler such as the conductive powder and the thixotropy agent was not properly blended.

A fourth problem is to solve the adhesion failure between the bump abutting part and the wiring pattern after the lamination press. In addition to the case where the adhesive strength of the binder itself is weak, it tends to occur when the curing degree of the bumps is too advanced. The present invention aims to solve the above problems.

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to solve the above problems, and completed the present invention. That is, the present invention includes (1) a resin selected from at least one of a melamine resin, a phenol resin, and an epoxy resin, a conductive powder, and a divalent alcohol having a boiling point of 180 ° C. or higher and /
Alternatively, a conductive paste composition comprising a solvent containing trivalent alcohol. (2) Conductivity characterized by containing a melamine resin, a phenol resin and an epoxy resin, a conductive powder and a solvent containing a divalent alcohol and / or a trivalent alcohol having a boiling point of 180 ° C. or higher. Paste composition. (3) The conductive paste composition according to (2), wherein the epoxy resin has a softening point of 80 to 130 ° C. (4) The printed wiring according to any one of (1) to (3). Conductive paste composition for board interlayer connection (5) The conductive paste composition according to any one of (1) to (3).
The present invention relates to a printed wiring board using a strike composition.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.

The epoxy resin used in the present invention is METTL
An epoxy resin having a softening point measured by an ER FP-90 automatic softening point measuring device of 80 ° C. or higher and 130 ° C. or lower is preferable,
More preferably, it is an epoxy resin of 95 ° C or higher and 125 ° C or lower. When the softening point of the epoxy resin is in this range, the penetration of the bump through the insulator is good, the bump is not cracked, and the adhesive force between the bump and the copper foil is large, which is preferable.

As these epoxy resins, a bisphenol type epoxy resin, a trisglycidyl type epoxy resin, a tetraglycidyl type epoxy resin and a novolac type epoxy resin can be used, but preferably, a solid bisphenol type epoxy resin alone or A mixture of solid bisphenol type epoxy resin and novolac type epoxy resin is preferable. Even when the solid bisphenol type epoxy resin and the novolac type epoxy resin are mixed, the softening point is 80 ° C to 130 ° C.
It is preferably in the range of ° C. It is not preferable to use the novolac resin alone because the bump hardness increases but the adhesive strength decreases.

It is preferable to use a resin selected from any one of a melamine resin, a phenol resin and an epoxy resin, and a mixing ratio of the epoxy resin to the melamine resin and the phenol resin is melamine resin and phenol.
300 parts by mass of epoxy resin to 100 parts by mass of resin
5 parts by mass is preferable, and particularly preferably 100 parts by mass to 1 part.
0 mass part is preferable. If the amount of epoxy resin is large, the hardness of the bump is insufficient, and if it is too small, the adhesive force is insufficient and the bump becomes brittle. The proportion of the melamine resin is preferably 20 parts by mass to 100 parts by mass, more preferably 30 parts by mass to 70 parts by mass, relative to 100 parts by mass of the phenol resin.

In the present invention, a curing agent (hereinafter referred to as a curing agent), which is a latent curing agent for the epoxy resin, may be used within the range where the bump performance is not deteriorated. As these curing agents, dicyandiamide, diaminodiphenyl sulfone,
Examples include phenol resin latent imidazole and the like.
The curing agents can be used alone or in combination of two or more. When selecting a curing agent, the pot life is long, the degree of bump curing is easy to control, the curing temperature is the same as the molding temperature of the printed wiring board, and the generation of by-products that cause voids occurs. Considered to be extremely small.

In the present invention, as the conductive powder, for example, metal powder such as silver, gold, copper and solder powder, alloy powder or mixed metal powder thereof can be used.
Copper is preferred. The amount of conductive metal powder used is 300 to 2000 parts by mass, preferably 450 to 1000 parts by mass, based on 100 parts by mass of the total amount of the resin.

The ratio of the above-mentioned conductive metal powder is the total amount of resin 1
When the amount is less than 300 parts by mass with respect to 00 parts by mass, good conductivity may not be obtained in some cases. When the ratio of the metal powder is more than 2000 parts by mass, not only the fluidity of the paste is lowered and the printability is deteriorated, but also the binding force of the metal powder of the obtained cured body is weakened and the bump is cracked. In some cases, the tip of the bump is apt to fly, resulting in poor connection and short circuit.

The solvent used in the present invention is different from that used for dissolving melamine resin, phenol resin, epoxy resin and the like. The solvent of the present invention has a boiling point of 180 ° C.
As mentioned above, those selected from divalent alcohols and / or trivalent alcohols can be mentioned. For example, petamethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3 butylene glycol, 1,4 butylene glycol, butyl glycol.
And butyl diglycol, ethyl diglycol, glycerin and the like. The compounding amount of the solvent of the present invention is the total amount of melamine resin, phenol resin and epoxy resin 1
It is used in an amount of 1 part by mass to 70 parts by mass, preferably 5 parts by mass to 50 parts by mass, relative to 00 parts by mass. The solvent of the present invention is used in combination with other solvent for dissolving the resin. As the other solvent, known solvents can be used without particular limitation. For example, ester compounds such as ethyl acetate and butyl acetate, cellosolves such as ethyl cellosolve and butyl cellosolve, carbitols such as ethyl carbitol and butyl carbitol, isopropanol, butanol.
And alcohols such as alcohol. The above solvents may be used singly or as a mixture of two or more kinds, but when forming bumps by printing with a metal mask plate or screen printing, carbitol and cellosolves should be used in consideration of plate shaving. preferable. By adding the solvent of the present invention to these solvents, the height (average value) of the conical bumps can be reduced to about 10 times without sharpening like the conical bumps formed from the conventional conductive paste composition. It can be formed 10 μm higher. The distribution of the conical bumps formed by printing is 3σ, which is 25 μm or more in the conventional case.
It can be controlled to less than μm. Thus, it is possible to prevent defective penetration of the insulator layer, and prevent defective connections due to cracking of the bumps during penetration and lamination pressing, and short circuit of the circuit due to jumping of the tips of the bumps. The amount of the other solvent used is 30 parts by mass to 1 part by mass based on 100 parts by mass of the total amount of the melamine resin, the phenol resin and the epoxy resin.
00 parts by mass is preferred. Furthermore, it is used in a ratio of 40 parts by mass to 60 parts by mass.

In the present invention, known additives may be added within a range that does not significantly deteriorate the characteristics. Examples of such additives include thixotropy-imparting agents, defoaming agents, dispersants, rust preventives, reducing agents and the like.

The method for producing the conductive paste of the present invention is not particularly limited, but the above-mentioned melamine resin, phenol resin,
A method in which an epoxy resin, a curing agent, a conductive metal powder, a solvent for dissolving the resin and the solvent of the present invention are premixed and kneaded using a three-roll mill to obtain a paste and defoam under vacuum. Is mentioned. Alternatively, there is an inexpensive method using a propeller-less stirrer that also serves as a method of removing. In particular, the use of a propeller-less stirrer is effective in stabilizing the bump height variation when performed immediately before printing.

In the present invention, the viscosity measured by Malcol's spiral viscometer at 10 revolutions / min at 25 ° C. is 10
0 Pa · s to 400 Pa · s, preferably 200
Pa · s to 300 Pa · s are suitable. See also lo
g (viscosity at 10 rpm / 5 viscosity at 5 rpm) / log (1
The thixo ratio calculated at 0 rpm / 5 rpm) is 0.3 or more and 1.0 or less, preferably 0.4 or more and 0.9 or less. If the above properties are deviated, the metal mask plate or the screen plate may be poorly wet, it may be difficult to pass through the holes of the plate, and even if printing is possible, a sufficient bump height may not be obtained.

In the present invention, the hardness of the bump measured by a micro hardness meter is preferably 30 or more. If the hardness is less than 30, it may be difficult to penetrate the insulator.

The conductive paste of the present invention can be printed by a known method such as screen printing, metal mask printing, dispenser and the like.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The blending ratio is parts by mass, and evaluation and measurement were according to the following methods.

(1) A softening point epoxy resin was melted and measured with a METLER FP-90 automatic softening point measuring device at a temperature rising rate of 1 ° C./min.

(2) The hardness paste was applied to the M surface of the copper foil (electrolytic copper foil surface having no gloss on the electrolytic solution side) to a thickness of 200 μm, and then 20 minutes at 160 ° C.
Minute drying was performed to obtain a sample. Hardness is micro hardness meter MX-T5
0 (Matsuzawa Seiki Co., Ltd.), test temperature 23 ℃, test load 2
It was measured at 5 kgf and a load holding time of 15 seconds.

(3) Copper foil peeling strength After applying the paste to the M side of the copper foil to a thickness of 200 μm,
It was dried at 160 ° C. for 20 minutes. A copper foil was placed on the coated surface with the M side facing down, and the sample was cured by a press at 180 ° C. for 60 minutes. The copper foil peeling strength (N / cm) was measured according to JIS C6481.

(4) Prepreg penetration, bump cracking
A conductive paste was printed on an electrolytic copper foil having a chip thickness of 18 μm through a metal mask plate having a thickness of 0.3 mm formed by forming holes having a diameter of 0.3 mm at predetermined positions. Printed conductive paper
The strike was dried at 160 ° C. for 10 minutes, and then the same metal mask plate was used to print at the same position and the drying treatment was repeated 4 times. After the fourth printing, it was dried at 160 ° C. for 20 minutes to form a conical conductive bump. After that, FR4 type prepreg in which glass cloth was impregnated with epoxy resin was placed on the electrolytic copper foil provided with the conductive bumps, and the bumps were passed through the prepreg through a dedicated penetrating machine. The state after penetration was observed with a 20 × optical microscope to determine prepreg penetration, bump cracking, and chipping. a) Good penetrability: All pass through the prepreg. Bad: There is a bump that does not penetrate the prepreg. b) Good cracking and chipping of bumps: The bumps that penetrate the prepreg and project are conical. Bad: The tip of the protruding bump is chipped, cracked, or cracked.

Example 1 50 parts of melamine resin, 50 parts of phenol resin, 25 parts of bisphenol A type epoxy resin (softening point; 125 ° C.), 10 parts of naphthalene novolac type epoxy resin (softening point of 96 ° C.) were mixed with acetic acid. It was dissolved in 88 parts of diethylene glycol monobutyl ether and 10 parts of propylene glycol (boiling point 186 ° C.). 3.9 parts of diaminodiphenyl sulfone, 2-phenyl-4,5
0.1 part of dihydroxymethyl imidazole, silver powder 80
Add 0 parts and 17 parts of Aerosil, and use a universal mixer for 30
Premix for minutes. Then, the mixture was kneaded with a triple roll to obtain a conductive paste.

The softening point of the mixture of bisphenol A type epoxy resin and naphthalene novolac type epoxy resin is 115.
It was ℃. As a result of measuring the obtained conductive paste by the method described in the previous term, the viscosity was 260 Pa · s / 25.
C., thixo ratio was 0.5, hardness was 43, copper foil peeling strength was 6 N / cm, penetration of prepreg was good, and bumps were not broken or chipped.

(Examples 2 to 7) Table 1 shows the evaluation results of the conductive pastes of Examples 2 to 6 having the composition as shown in Table 1 and obtained by the same operation as in Example 1. .

Comparative Example 1 5 parts of bisphenol A type epoxy resin, 50 parts of melamine resin and 5 parts of phenol resin.
0 parts, diethylene glycol monobutyl ether acetate 5
Example 1 except that 8 parts, 1 part of diaminodiphenyl sulfone, 0.1 part of 2-phenyl-4,5-dihydroxyimidazole, 600 parts of silver powder and 16 parts of Aerosil were used.
And mixed in the same manner as above to obtain a conductive paste. As a result of measuring the obtained conductive paste by the method described above, the viscosity was 250 Pa · s / 25 ° C., the thixo ratio was 0.5, the hardness was 43, the copper foil peeling strength was 2 N / cm, and the prepreg Penetration was good, but bumps cracked and chipped. The results are shown in Table 2.

Comparative Examples 2 to 4 Table 2 shows the evaluation results of the conductive pastes of Comparative Examples 2 and 3 obtained by the same composition as in Table 1 and the same operation as in Comparative Example 1.

The abbreviations in the table mean the following, respectively. Epoxy resin A: BPA type solid epoxy resin (softening point: 1
25 ° C) Epoxy resin B: BPA type solid epoxy resin (softening point: 1
00 ° C) Epoxy resin C: BPA type solid epoxy resin (softening point; 7
5 ° C.) Epoxy resin D: naphthalene novolac type epoxy resin (softening point; 96 ° C.) Phenolic resin: para-hydroxystyrene resin Melamine resin: Cymel 350 DDS: diaminodiphenyl sulfone 2PHZ: 2-phenyl-4,5-dihydroxymethylimidazole

[0032]

[Table 1]

[Table 2]

When the conductive paste of the present invention is used,
It is possible to form a bump having a good prepreg penetrability, which does not break or break at the time of penetrating or pressing and has a large adhesive force between the bump after penetrating and the wiring pattern.
As a result, in the production of a printed wiring board having a through-type conductive wiring portion, the yield is improved and the connection reliability is improved.

[0033]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyomi Yasuda             Mitsui Chemicals Co., Ltd. 3 Chikusaigan, Ichihara, Chiba Prefecture             Inside the company F term (reference) 4E351 AA03 BB01 BB31 CC11 CC22                       DD04 DD05 DD06 DD24 EE15                       EE16 EE24 GG02 GG09 GG16                 4J002 CC031 CC181 CD001 CD051                       CD061 CD081 DA066 DA076                       DC006 EC047 EC057 FD116                       FD207 GQ00 GQ02                 5E346 CC04 CC09 CC32 DD02 DD12                       DD32 EE01 FF35 GG19 GG28                       HH07 HH11                 5G301 DA55 DA57 DA60 DD01

Claims (5)

[Claims] 1. A resin selected from at least one of a melamine resin, a phenol resin and an epoxy resin, a conductive powder, and a divalent alcohol and / or a trivalent alcohol having a boiling point of 180 ° C. or higher. A conductive paste composition comprising: 2. A conductive sheet containing a melamine resin, a phenol resin, an epoxy resin, a conductive powder, and a divalent alcohol and / or a trivalent alcohol having a boiling point of 180 ° C. or higher. Strike composition. 3. The softening point of the epoxy resin is 80 ° C. to 130 ° C.
3. The conductive paste according to claim 2, wherein the conductive paste is at a temperature of ° C.
Strike composition 4. The conductive paste composition for printed wiring board interlayer connection according to claim 1. 5. A printed wiring board using the conductive paste composition according to claim 1.