JP2003086939A - Method of manufacturing multilayered printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a multilayered printed wiring board that is improved in thermal reliability can be manufactured by using specific metal foil and a specific thermosetting resin for a metal foil-clad laminated board and prepreg. SOLUTION: A highly reliable multilayered printed wiring board is obtained by using a resin having a glass transition point of >=165 deg.C and a pyrolysis starting temperature of >=345 deg.C as the matrix resin used for forming the metal foil-clad laminated board and prepreg. In addition, metal foil having a thickness of <=0.035 mm and an elongation percentage of >=12% at 180 deg.C is used for the metal foil-clad laminated board.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electric / electronic device,
The present invention relates to a method for manufacturing a multilayer printed wiring board used for communication equipment and the like.

[0002]

2. Description of the Related Art Conventionally, a multilayer board used for producing a printed wiring board is semi-cured by heat-drying after impregnating a base material such as glass cloth with a thermosetting resin composition such as an epoxy resin composition. To make a prepreg,
A required number of the prepregs are stacked, metal foils such as copper foils are arranged on one side or both sides of the prepregs, and the prepregs are laminated by heating and pressing to form a metal foil-clad laminate.
Then, after etching the metal foil on the surface of the metal foil-clad laminate, an inner layer substrate having guide marks used for manufacturing a conductor circuit and a printed wiring board is formed on the surface, and then a rough surface is formed if necessary. Then, on the inner layer substrate on which the conductor circuits and the like are formed, a required number of prepregs produced in the same manner as above are stacked on one side or both sides, and a metal foil is placed on one side or both sides as necessary. It is manufactured by arranging and stacking, heating and pressing and molding.

As a method of manufacturing a printed wiring board using this multilayer board, a guide mark formed on the inner layer substrate is used, and a hole is drilled in the multilayer board by a drill machine or a laser machine based on this guide hole. After that, the wall surface of the hole formed by the drill machine and the laser machine is plated with through holes, and the outer layer metal foil is etched to form the outer layer conductor circuit.

The metal foil used for producing the metal foil-clad laminate used for these multilayer printed wiring boards is 180
It is common to use one having an elongation at 2 ° C of 2 to 6%.

[0005] With the higher performance of communication equipment typified by routers and servers in recent years, the multi-layered printed wiring boards used therein are becoming higher in density and higher in multi-layer, and highly reliable multi-layer materials are required. Has been done. The matrix resin that has been used in multilayer printed wiring boards so far is generally FR-4 (T
g = about 120 to 130 ° C. to medium Tg material (Tg = about 14)
Those of 0 to 160 ° C.) have been widely used. But,
In multilayer printed wiring boards in this field, IPC-TM
It has become a necessary characteristic that there is no abnormality after a heat resistance test of solder 288 ° C. for 10 seconds float 6 cycles specified in 650. The above-mentioned FR-4 and medium Tg matrix resins are thermally unstable under high temperature treatment and have a low thermal decomposition temperature. Therefore, blister of a multilayer printed wiring board or resin recession of a through hole wall surface, etc. Was having problems.

[0006] Multilayer printed wiring boards are moving toward higher densities, and as wiring circuits of multilayer printed wiring boards are becoming finer, the metal foil used for the inner layer circuit board is more than that conventionally used. Thinning is advancing, and metal foils having a thickness of 35 μm or less have come to be widely used. Therefore, I
There was a problem that foil cracks occurred in the inner metal foil during the heat resistance test of solder 288 ° C. for 10 seconds float 6 cycles specified in PC-TM650.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to elongate the metal foil used for the inner layer circuit board at a high temperature and the glass transition. Providing a method for manufacturing a multilayer printed wiring board that uses a metal foil-clad laminate or prepreg that uses a matrix resin with a limited temperature (Tg) and thermal decomposition temperature to obtain a multilayer board with excellent heat resistance and reliability To do.

[0008]

As a result of repeated studies to solve the above-mentioned problems, as a matrix resin used for producing a metal foil-clad laminate and a prepreg, a material having a high Tg and a high thermal decomposition temperature is used. Therefore, it is possible to improve the thermal reliability, and by optimizing the elongation rate of the metal foil at high temperature, 288 defined in IPC-TM650.
The problem was solved by finding the range where the heat resistance test of 6 cycles of float at 10 ° C was cleared.

In the method for producing a multilayer printed wiring board according to the present invention, a plain weave glass cloth is impregnated with a thermosetting resin composition, laminated with a metal foil, and then heated and pressed to produce a metal foil. After etching the metal foil of the laminated laminate, an inner layer circuit board having a conductor circuit formed on the surface and a prepreg made by impregnating a plain weave glass cloth with a thermosetting resin composition are laminated, and then heated and pressed. In the method for producing a multilayer board to be produced, an inner layer circuit board having a metal foil having a thickness of 35 μm or less is contained as a constituent material, and the elongation of the metal foil having a thickness of 35 μm or less at 180 ° C. is 12% or more, Glass transition temperature (Tg) is 165 ° C
(TMA method) or more.

The invention of claim 2 is the method of manufacturing a multilayer printed wiring board according to claim 1, which is a high multilayer board having 10 or more layers.

According to a third aspect of the present invention, in the method for manufacturing a multilayer printed wiring board according to the first or second aspect, the thermal decomposition start temperature of the matrix resin is 345 ° C.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer board according to the present invention is obtained by impregnating glass cloth with a thermosetting resin composition having a glass transition temperature of 165 ° C. or higher (TMA method) and a thermal decomposition initiation temperature of 345 ° C. or higher. The metal foil of the metal-clad laminate prepared by laminating with a metal foil having a thickness of 35 μm or less and an elongation at 180 ° C. of 12% or more, and then heating and pressurizing the metal foil is an inner layer having a conductor circuit formed on the surface by etching. Circuit board and thickness 20-20
It is obtained by laminating a predetermined number of prepregs prepared by impregnating a 0 μm glass cloth with a thermosetting resin composition, and then heating and pressing. (The outermost layer also has a 12% elongation at 180 ° C.
It is desirable to use the above metal foil. )

The matrix resin used for producing the metal foil-clad laminate has a glass transition temperature of at least 165 ° C. (TMA).
It is important that the material has a thermal decomposition starting temperature of 345 ° C. or higher. If the glass transition temperature of the matrix resin used for producing the metal foil-clad laminate and the prepreg is 165 ° C. or lower (TMA method), the expansion amount in the thickness direction (Z direction) will rapidly increase, resulting in a through hole. Reliability is reduced. Also, the thermal decomposition temperature is 30
In the case of a material near 0 ° C., in a cycle test of 288 ° C. for 10 seconds float, thermal decomposition of the resin starts, which causes resin recession and swelling, and a decrease in reliability becomes a problem.

The metal foil 180 having a thickness of 35 μm or less is used.
By setting the elongation rate at 12 ° C to 12% or more, 28
It becomes possible to follow the expansion of the laminated plate and the prepreg during the 8 ° C. 10 second float cycle test, and the stress due to expansion / contraction does not concentrate on the inner metal foil. Therefore, foil cracks and the like can be improved.

The metal foil used in the present invention has a thickness of 35.
It is limited to metal foils of μm or less. The thickness of the metal foil is 35μ
When it exceeds m, the elongation rate of the metal foil is large and the tensile strength is strong, so that foil cracks of the inner layer metal foil tend not to easily occur. In the present invention, Tg is 165 ° C. (T
By using the resin of the MA method) or more, the drawbacks when the metal foil having a thickness of 35 μm or less is formed are improved. When the thickness of the metal foil exceeds 35 μm, it becomes difficult to form a fine wiring circuit due to the problem of etching accuracy.

In addition, the metal foil used in the present invention has a roughness of 4 μm in view of etching accuracy and impedance control.
It is preferably a low profile foil of m or less. The ratio of the thermosetting resin composition with which the glass cloth is impregnated is preferable because it can be manufactured in an appropriate range so that the circuit of the inner layer circuit board can be sufficiently embedded during molding.

As the thermosetting resin composition used in the present invention, both the thermosetting resin composition used for producing the metal foil-clad laminate and the thermosetting resin composition used for producing the prepreg are epoxy resin type, Thermosetting resins as a whole can be used, such as phenol resin-based, polyimide resin-based, unsaturated polyester resin-based, polyphenylene ether resin-based, etc. alone, modified products, and mixtures. The types of the thermosetting resin composition used for producing the metal foil-clad laminate and the thermosetting resin composition used for producing the prepreg may be the same or different.

The thermosetting resin composition contains a thermosetting resin as an essential component and, if necessary, a curing agent for the thermosetting resin, a curing accelerator, an inorganic filler and a solvent. be able to. A thermosetting resin having a low self-hardening property such as an epoxy resin needs to contain a curing agent or the like for curing the resin.

When the thermosetting resin composition is an epoxy resin type, it is preferable because it has a good balance of electrical characteristics and adhesiveness. Examples of the epoxy resin contained in the epoxy resin-based resin composition include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and bisphenol F. Examples thereof include novolac type epoxy resins, cresol novolac type epoxy resins, diaminodiphenylmethane type epoxy resins, and epoxy resins flame-retarded by halogenating a part of hydrogen atoms in these epoxy resin structures. Examples of the curing agent contained in the epoxy resin-based resin composition include amide-based curing agents such as dicyandiamide and aliphatic polyamide, and amine-based curing agents such as ammonia, triethylamine and diethylamine, and phenol novolac resins. Examples include phenolic curing agents such as cresol novolac resin and p-xylene-novolac resin, and acid anhydrides.

Examples of the inorganic filler that can be contained in the thermosetting resin composition include silica, calcium carbonate, aluminum hydroxide, talc and other inorganic powder fillers, glass fibers, pulp fibers and synthetic fibers. , Fibrous fillers such as ceramic fibers, and the solvent that can be contained in the thermosetting resin composition is N,
Amides such as N-dimethylformamide, ethers such as ethylene glycol monomethyl ether, acetone,
Examples thereof include ketones such as methyl ethyl ketone, alcohols such as methanol and ethanol, and aromatic hydrocarbons such as benzene and toluene.

The method of impregnating the glass cloth with the thermosetting resin composition is not particularly limited, and a general method can be applied. After impregnating the glass cloth with the thermosetting resin composition, it may be dried by heating if necessary.

As the metal foil used in the present invention, a single, alloy, or composite metal foil of copper, aluminum, brass, nickel or the like can be used, and a metal foil laminated instead of the metal foil is coated on one side with metal. A laminated board or a double-sided metal-clad laminated board can also be used. The metal foil is not limited to being used only for producing a metal foil-clad laminate, and may be used by laminating it on one side or both sides of the laminate in which the inner layer substrate and the prepreg are laminated. As the thickness of this metal foil, when used in the production of a metal foil-clad laminate,
The thickness is generally 0.003 to 0.035 mm, and when it is laminated on one side or both sides of the laminate in which the inner layer substrate and the prepreg are laminated, the thickness is generally 0.003 to 0.035 mm.

The conditions for heating and pressing when producing the metal foil-clad laminate and the conditions for heating and pressing after laminating the inner layer substrate and the prepreg are appropriately adjusted depending on the conditions under which the thermosetting resin composition is cured. It is sufficient to heat and pressurize, but if the pressurizing pressure is high, the dimensional shrinkage of the conductor circuit may vary greatly. Therefore, it is preferable to pressurize as low as possible within the range where the formability is satisfied. It is preferable to heat and pressurize under a reduced pressure atmosphere of 300 Torr or less because the moldability becomes good.

The method for etching the metal foil on the surface of the metal foil-clad laminate is not particularly limited, and a general method can be applied depending on the metal foil and the etching resist used for the etching.

[0025]

Example 1 As a thermosetting resin composition, an epoxy resin resin composition comprising the following two kinds of epoxy resins, a curing agent, a curing accelerator and a solvent was used.・ Epoxy resin 1: 50 parts by weight of bisphenol A novolac type epoxy resin (Dainippon Ink and Chemicals, Inc., Epicron N868, trade name) ・ Epoxy resin 2: Brominated bisphenol A type epoxy resin (Sumitomo Chemical Co., Ltd., ESB-400, trade name) 50 parts by weight-Curing agent: bisphenol A novolak resin (YLH-129, manufactured by Japan Epoxy Resin Co., Ltd., trade name) 40 parts by weight-Curing accelerator: 1-cyanoethyl-2-phenylimidazole 1 Parts by weight / solvent: 90 parts by weight of methyl ethyl ketone

This resin composition was mixed with glass cloth (# 10
80 type: weight 48 g / m ² ) and the amount of the thermosetting resin composition after drying was adjusted to 62 parts by weight based on 100 parts by weight of the total amount of the thermosetting resin composition and the glass cloth. And impregnated with it, and then dried at a maximum temperature of 165 ° C. to prepare a prepreg.

Then, a copper foil having a thickness of 18 μm (elongation at 180 ° C. of 16
%) Was placed and laminated, this laminate was sandwiched between metal plates, and heated and pressed at a maximum temperature of 180 ° C. and a pressure of 3.0 MPa for 90 minutes to form a double-sided copper-clad laminate.

Next, a predetermined number of the obtained double-sided copper-clad laminates were subjected to surface treatment, a predetermined number of prepregs were arranged and laminated, and the laminates were sandwiched between metal plates, the maximum temperature was 180 ° C., and the pressure was 2 A multilayer board was produced by heating and pressing at 0.5 MPa for 80 minutes and molding. Glass transition temperature (T
g) was 174 ° C. (TMA method). The thermal decomposition starting temperature was 347 ° C.

Example 2 A double-sided copper-clad laminate and a prepreg were prepared in the same manner as in Example 1 except that an 18 μm copper foil (elongation at 180 ° C., 20%) was obtained to obtain a multilayer board.

Example 3 A double-sided copper-clad laminate and a prepreg were prepared in the same manner as in Example 1 except that a 12 μm copper foil (elongation at 180 ° C., 12%) was obtained to obtain a multilayer board.

Example 4 A double-sided copper-clad laminate and a prepreg were prepared in the same manner as in Example 1 except that a 12 μm copper foil (elongation at 180 ° C., 18%) was obtained.

Comparative Example 1 A double-sided copper-clad laminate and a prepreg were prepared in the same manner as in Example 1 except that a 18 μm copper foil (elongation at 180 ° C .: 9%) was obtained to obtain a multilayer board. At this time, the glass transition temperature (Tg) was 173 ° C. (TMA method). The thermal decomposition starting temperature (Tg) at this time was 346 ° C.

Comparative Example 2 After subjecting a predetermined number of double-sided copper-clad laminates (18 μm copper foil: elongation at 180 ° C. 16% of 16%) of another company's material to a surface treatment and arranging and laminating a predetermined number of prepregs of another company's material , Sandwich this laminate between metal plates, maximum temperature 180 ℃, pressure 2.5
A multilayer plate was produced by heating and pressing at 80 MPa for 80 minutes for molding. The glass transition temperature (Tg) at this time is 163 ° C. (Tg)
MA method). Thermal decomposition start temperature (Tg) at this time
Was 298 ° C.

(Evaluation, Results) Examples 1 to 4 and Comparative Example 1
About the multilayer board obtained by -2, the solder float test of 288 degreeC 10 second 6 cycle was done based on IPC-TM650.

The results are shown in Table 1 and are shown in Examples 1 to 4
It was confirmed that, compared with Comparative Example 1, the foil crack resistance was improved. In addition, each of Examples 1 to 4 is a comparative example 2.
It was confirmed that the heat resistance (resin recession, blistering) by soldering and the through-hole reliability were improved, though the structure of the multilayer board remained the same.

[0036]

[Table 1]

[0037]

According to the present invention, the glass transition temperature is 165 ° C. or higher and the thermal decomposition starting temperature is 345 as the matrix resin used for producing the metal foil-clad laminate and the prepreg.
In the case of applying a material characterized in that the temperature is ℃ or more, the thickness of the metal foil used for the metal foil-clad laminate is 0.035 mm or less, and the elongation at 180 ° C. is 12% or more. It is possible to obtain a multilayer printed wiring board having excellent heat resistance, foil crack resistance, and reliability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor You Murai             Hitachi Chemical, 1500 Ogawa, Shimodate City, Ibaraki Prefecture             Shimodate Office of Industry Co., Ltd. F-term (reference) 5E346 CC04 CC09 CC10 CC12 CC13                       CC32 CC34 CC37 DD12 EE09                       HH21

Claims (3)

[Claims] 1. A metal cloth of a metal-clad laminate prepared by impregnating a plain weave glass cloth with a thermosetting resin composition, laminating it with a metal foil, and then heating and pressurizing the metal foil to etch a conductor circuit on the surface. In the method for producing a multilayer printed wiring board, the inner layer circuit board on which is formed and a prepreg produced by impregnating a plain weave glass cloth with a thermosetting resin composition are laminated, and then heated and pressed to obtain a thickness of 35 μm or less. The inner layer circuit board having the metal foil of No. 3 is included in the constituent materials, the elongation of the metal foil having a thickness of 35 μm or less at 180 ° C. is 12% or more, and the glass transition temperature (hereinafter referred to as Tg) of the matrix resin is 165 ° C. (TMA method)
A method for manufacturing a multilayer printed wiring board having the above. 2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the multilayer printed wiring board is a high multilayer board having 10 or more layers. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the thermal decomposition start temperature of the matrix resin is 345 ° C. or higher.