JP2002264157A - Method for producing laminated plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a laminated plate in which surface roughness, warpage, a dimensional change percentage, and the dispersion of the dimensional change percentage are controlled. SOLUTION: In a method for producing the laminated plate in which a sheet- shaped prepreg impregnated with a thermosetting resin is held between a pair of specular plates, heated, pressed between hot plates, and cooled with the pressing lifted, the pressing is lifted when the hardness of the prepreg is at least 70% and below 100%, and the cooling with the pressing lifted is done while the temperature of the specular plate and the heated, pressed laminated plate is kept without disassembly of the specular plate and the laminated plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a laminate, and more particularly to a method for manufacturing a copper-clad laminate suitable for a printed wiring board substrate.

[0002]

2. Description of the Related Art A laminated board used as a substrate for a printed wiring board or the like is prepared by impregnating a sheet-like base material with a thermosetting resin and then curing the prepreg of one or more sets to a B stage by a pair of mirrors. It is manufactured by sandwiching it between face plates, heating and pressing it with a press hot plate, and press-molding it into a plate shape.

[0003] In the above-mentioned manufacturing process of a laminate, a copper-clad laminate for a printed wiring board is obtained by arranging copper foil on one or both surfaces of a prepreg, and when a release film or the like is used in place of the copper foil, an insulating plate is obtained. Is obtained.

In recent years, as electronic devices have become lighter, thinner and smaller, high-density mounting of electronic components on printed wiring boards has been progressing, and fine patterns of printed wiring boards have been advanced. For this reason, it is desired that the copper-clad laminate has a small surface roughness on the surface of the copper foil, a small warpage, a small dimensional change and a small variation in the process of processing the copper-clad laminate.

Conventionally, as a method of manufacturing a copper-clad laminate having a small surface roughness of a copper foil surface and a small dimensional change rate, a pressing pressure is reduced to a non-pressing state after completion of heating and pressing in a press forming step. A method is known in which cooling is performed in a non-pressurized state (Japanese Patent Publication No. 62-1827). According to this method, since the molding pressure is applied until the heating and pressurization is completed,
There is an advantage that the surface roughness of the copper foil surface can be reduced.

[0006]

However, this conventional method has a problem that a large amount of molding distortion remains when the prepreg is cured because the molding is performed under pressure until the heating is completed. Therefore, the dimensional change rate is not only large and insufficient, but also has a disadvantage that the dimensional change rate has a large variation. In addition, there is also a disadvantage that the warpage becomes large because a large molding distortion remains during prepreg curing.
Furthermore, since press molding is performed until the completion of heating, there has been a problem that press molding time is lengthened and productivity is poor.

Therefore, the present invention provides a copper-clad laminate having a small surface roughness on the surface of a copper foil, a small warpage in a processing step, a small dimensional change and a small variation thereof, and mainly suitable for fine patterns with good productivity. Making it a technical issue.

[0008]

In order to solve the above-mentioned problems, the present invention provides a sheet-like prepreg impregnated with a thermosetting resin, which is sandwiched between a pair of mirror-surfaced plates, heated and pressed between hot plates, and heated. In the method of manufacturing a laminate by cooling under a pressure-free state where the pressure is released, the time point at which the above-mentioned pressure-free state is set is such that the degree of cure of the prepreg represented by the following formula is in the range of 70% or more and less than 100%. At this point, the cooling in the non-pressure state is performed while keeping the temperature without dismantling the mirror plate and the heated and pressed laminate. CF = Tg ₁ / Tg ₂ × 100 CF: Degree of curing of prepreg (%) Tg ₁ : Glass transition point of prepreg at the time of no pressure (° C.) Tg ₂ : Glass transition point of completely cured prepreg (° C.)

In the present invention, as described above, the point at which the prepreg is brought into the pressureless state is the point at which the degree of cure of the prepreg is in the range of 70% or more and less than 100%. This is because if the degree of curing of the prepreg is less than 70%, the curing reaction of the prepreg resin is insufficient, and there is a disadvantage that delamination (delamination) and voids occur when the prepreg is put in a pressureless state. Further, there is a disadvantage that the surface roughness of the copper foil surface is increased. On the other hand, when the degree of cure of the prepreg becomes 100%, the prepreg is kept in a pressurized state until the curing reaction is completed, resulting in a disadvantage that the warpage increases, the dimensional change rate and the variation thereof increase.

Further, in the present invention, it is necessary to perform cooling in a non-pressurized state without disassembling the mirror plate and the heated and pressed laminate. This is because, when cooling in a non-pressurized state is performed after disassembling the mirror plate and the heated / pressed laminate, the cooling rate of the laminate is increased, and a predetermined degree of curing cannot be obtained. . Further, since the support of the laminated plate is lost at the time of cooling, there is a disadvantage that warpage is increased.

In the present invention, cooling is performed while keeping the temperature in order to completely cure the prepreg.
In order to obtain a predetermined degree of curing of the laminate, a method using a press machine that has been heated and pressurized, or a method using a separate heating device to completely cure the laminate is also conceivable. However, in the former, the number of heating / pressing molding cycles of the press machine decreases, and the productivity decreases. In addition, the latter requires another heating device, which is not preferable in terms of productivity and economy.

As a method of cooling while keeping the temperature, a method of covering with a heat retaining sheet, a method of cooling in a vacuum box, and the like can be adopted, and there is no particular limitation. Further, the heat retention condition may be set appropriately so that the prepreg is completely cured.

The glass transition point of a completely cured prepreg means the glass transition point of the prepreg at the time when the curing reaction of the prepreg is completed. Specifically, it refers to the maximum temperature of the glass transition point of the prepreg (the glass transition point of the laminate) reached when the heating and pressure molding is continued at a predetermined temperature in the press molding step. Usually, the laminated board is subjected to a heat treatment before the press forming step or the processing step of the laminated board so that the degree of cure of the prepreg is set to 100% in order to minimize the influence of the shrinkage of the prepreg resin due to the heat received in the subsequent process. You.

In the present invention, as a sheet-shaped prepreg impregnated with a thermosetting resin, inorganic or organic fibers such as glass fiber, paper, aramid, polyester, etc. are matted,
After impregnating a non-woven fabric or woven base material with a thermosetting resin such as an epoxy resin, a phenol resin, a melamine resin, an unsaturated polyester resin, or a polyimide resin, a material cured to the B stage can be used. In particular, a combination of a glass fiber having high rigidity and easily remaining molding distortion, and an epoxy resin having excellent adhesion and a small generation of volatile components upon curing of the resin and having a small delamination generation factor is preferable.

The manufacturing process of the laminate according to the present invention is as follows. First, a sheet-shaped prepreg impregnated with the thermosetting resin is prepared. Next, one or more of the above prepregs are laminated so that a laminate having a desired thickness is formed, and a release sheet such as a release film or a metal foil such as a copper foil is formed on both surfaces of the prepreg as necessary. The sheets are superimposed, sandwiched between a pair of mirror plates made of stainless steel or the like, formed into one or more sheets, inserted between press hot plates, and heated and pressed. The heating temperature and pressure are appropriately adjusted according to the resin fluidity and the curing rate during molding of the prepreg.

Next, the molding pressure is released before the degree of curing of the prepreg reaches 100% by heating and pressurizing, so that only the own weight of the laminated plate and the mirror surface plate is released.

In the cooling under pressureless condition, cooling is performed while keeping the temperature immediately after taking out from the press machine without dismantling the mirror plate and the laminated plate. When a heat insulating sheet is used for heat insulation, a sheet having excellent heat insulating properties is preferable, and any material having heat resistance higher than the molding temperature is not particularly limited.

According to the present invention, the latter stage of the prepreg curing is performed without restraint in a pressureless state, so that the curing shrinkage of the resin is free and the molding distortion at the time of curing can be minimized.
Thereby, it is considered that a material having a small warpage and a small dimensional change rate and its variation can be obtained. Further, it is considered that the fact that an appropriate load of only the own weight of the laminated plate and the mirror surface plate is applied contributes to the reduction of the surface roughness and the suppression of the warpage.

Further, according to the present invention, since the press forming is completed before the completion of the heating, the press forming time can be shortened.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, Examples 1 and 2 of the present invention
Comparative Examples 1 and 2 and Conventional Example 1 are shown. First, prepreg A
To 100 parts by weight of bisphenol A epoxy resin
2 parts by weight of dicyandiamide as a curing agent
Solid content of 1 part by weight of imidazole as a promoter
0% by weight of a varnish is applied to a glass woven fabric (210 g / m2). ^Two) Included
It was soaked to prepare a resin having a resin adhesion amount of 42%.

Three prepregs A are superimposed, copper foil of 18 μm thickness is superimposed on both surfaces thereof, and a pair of the components sandwiched between stainless steel mirror plates having a thickness of 10 mm is pressed through a cushion material. Inserted between boards. A hot platen temperature of 160 ° C., a molding pressure of 4.9 MPa, and a molding time of 35 minutes were used in Examples 1 and 90 minutes, and Examples 2 and 30 were used.
For 1 minute, Comparative Example 2 for 150 minutes,
The case of Conventional Example 1 for 120 minutes was used, the press pressure was released immediately after molding, and the product was immediately taken out of the press.

In Examples 1 and 2 and Comparative Examples 1 and 2, the sheets were covered with a glass wool sheet immediately after being taken out of the press machine, and after 24 hours, the temperature of the laminate was at room temperature (20 ° C.).
° C). For Inherited Example 1,
Immediately after taking out from the press machine, it was allowed to cool naturally.

In the measurement of the degree of hardening, the copper-clad laminate formed in the same configuration between different hot plates at the time of press molding was disassembled and separated from the mirror-finished plate immediately after decompression. The glass transition point of the laminated plate obtained by immersing the plate in water and quenching was determined by the DMA method (the measurement method was JIS C 6481 5.1).
7.2), and the comparison was made with the glass transition point of the copper-clad laminate obtained in Comparative Example 2 which was completely cured.

The surface roughness was measured by measuring the surface of the obtained copper-clad laminate according to JIS B 0601 and measuring the ten-point average roughness R
Indicated by z.

The dimensional change and the variation in the dimensional change were measured as follows. First, holes having a diameter of 1 mm are formed in the four corners of a test piece of 510 × 510 mm size, and a dimension between the holes is measured to be an initial dimension. Next, after the copper foil was removed by etching, a heat treatment was performed at 150 ° C. for 30 minutes, and the dimension between holes of the test piece was calculated as a dimensional change rate with respect to the initial dimension, and expressed as an average value. The variation in the dimensional change was represented by a standard deviation δn-1 when n = 50 holes were measured.

The warpage was measured by measuring the amount of warpage of the test piece after the heat treatment measured at the above dimensional change rate, and expressing the average value. Table 1 shows the results of the above.

[0027]

[Table 1]

From the results shown in Table 1, in the press forming step, the press forming pressure was set to a non-pressurized state in the range of 70% to less than 100% of the degree of curing of the prepreg, and the mirror plate and the laminated plate were kept warm without being disassembled. When cooled, no voids or delaminations occur, the surface roughness of the copper foil surface is small,
It was confirmed that a copper-clad laminate having a small warpage and a small dimensional change and its variation in the processing step was obtained.

[0029]

As described above, according to the present invention, there is no occurrence of voids or delamination, the surface roughness of the copper foil surface is small, and the warpage is small in the processing step.
The dimensional change rate and its variation are small, and a copper-clad laminate mainly suitable for fine patterns can be provided with high productivity.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/24 CFC C08J 5/24 CFC H05K 1/03 610 H05K 1/03 610L // B29K 63:00 B29K 63:00 105: 08 105: 08 B29L 9:00 B29L 9:00 C08L 63:00 C08L 63:00 F term (reference) 4F072 AA04 AA07 AB03 AB05 AB06 AB09 AB28 AB29 AB31 AD13 AD21 AD23 AD38 AD45 AG03 AH02 AK05 AK14 AL12 AL13 4F100 AB17C AB33C AG00A AG00B AG00D AK01A AK01B AK01D AK53A AK53B AK53D BA04 BA10A BA10C DG01A DG01B DG01D DG12 DH01A DH01B DH01D EJ052 EJ202 EJ472 EJ502 EJ82A EJ82B EJ82D GB43 JB13A JB13B JB13D JL02 JL04 4F204 AA39 AD03 AD04 AD16 AG03 AH36 AK07 AP02 AP05 FA20 FB01 FB24 FG09 FJ30 FN15 FN30 FQ16

Claims (4)

[Claims] 1. A sheet-like prepreg impregnated with a thermosetting resin is sandwiched between a pair of mirror plates, heated and pressurized between hot plates, and cooled in a pressure-free state where the pressurization is released. In the manufacturing method, the point of time when the above-mentioned pressure-free state is set is 10 times when the degree of curing of the prepreg represented by the following formula is 70% or more
A method for producing a laminated plate, wherein cooling in a non-pressurized state is performed while maintaining the temperature without dismantling the mirror plate and the heated / pressed laminated plate at a time point of less than 0%. . CF = Tg ₁ / Tg ₂ × 100 CF: Degree of curing of prepreg (%) Tg ₁ : Glass transition point of prepreg at the time of no pressure (° C.) Tg ₂ : Glass transition point of completely cured prepreg (° C.) 2. The method according to claim 1, wherein the laminate is a copper-clad laminate for a printed wiring board, using a prepreg obtained by impregnating a glass fiber base material with an epoxy resin. 3. The method according to claim 1, wherein a plurality of sheet prepregs are sandwiched between a pair of mirror plates. 4. The method according to claim 1, wherein a plurality of sets of mirror plates are inserted into the hot platen.