JP2002200633A - Method for manufacturing composite laminate plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a dimensional stability of a composite laminate plate or a metal foil-clad composite laminate plate (restrain a dimensional shrinkage thereof due to heating) by decreasing warp and twist thereof. SOLUTION: A surface layer pre-preg has a resin content of 40 to 50 mass % and its resin cure degree is adjusted so that a gel time in stroke cure at 160 deg.C is 90 to 150 sec. A core layer pre-preg has a resin content (including a compounded inorganic filler) of 87 to 93 mass % and its resin cure degree is adjusted so that a resin flow is 15 to 40 mass % when a 100 mm square pre-preg is heated and pressed under 5 MPa at 160 deg.C. A heat and press forming of the surface layer pre-preg and the core layer pre-preg is conducted by increasing the heating pressure from a first pressure of 2 to 4 MPa to a second pressure of 5 to 10 MPa. This pressure increase is conducted at a stage when the resin initiates curing after passing through a molten state. A pressure during cooling after forming is reduced from the second pressure to 0 to 1 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite laminate having a small warp and twist and excellent dimensional stability. This manufacturing method includes in its concept a method of manufacturing a metal-foil-clad composite laminate in which a metal foil such as a copper foil is integrated on the surface.

[0002]

2. Description of the Related Art In recent years, the development of electric and electronic devices has been remarkable, and printed wiring boards processed from metal foil-clad composite laminates have been used in both industrial and consumer fields.
It has been adopted for high-end equipment. For this reason, further improvement in quality and performance is required for the composite laminate.

[0003] A composite laminate is made by impregnating an epoxy resin into a glass fiber woven fabric and heating and drying the prepreg as a surface layer, impregnating an epoxy resin containing an inorganic filler into a glass fiber nonwoven fabric and heating and drying the prepreg to the core of the surface layer. These layers were formed by heating and pressing between press hot plates. If necessary, a metal foil such as a copper foil is integrally formed on the surface. Since the composite laminate uses a glass fiber nonwoven fabric for the core layer, the composite laminate has excellent machinability such as drilling and punching as compared with an epoxy resin laminate using a glass fiber woven fabric for all layers. And the electrical insulation characteristics and through-hole reliability as a printed wiring board,
Since it is equivalent to a glass fiber woven epoxy resin laminate, production has recently increased sharply.

However, since the composite laminate uses a glass fiber non-woven fabric for the core layer, warpage and torsion easily occur and the dimensional stability is inferior as compared with the glass fiber woven epoxy resin laminate. The use of glass fiber non-woven fabric for the core layer works for both good and bad.

[0005]

An object of the present invention is to reduce the warpage and twist of a composite laminate or a metal foil-clad composite laminate and improve dimensional stability (particularly, suppression of dimensional shrinkage due to heating). It is to make it.

[0006]

In order to solve the above-mentioned problems, a method for producing a composite laminate according to the present invention comprises a glass fiber woven prepreg used for a surface layer and a glass fiber nonwoven fabric used for a core layer of the surface layer. The prepregs are adjusted based on specific indices, respectively, and specific control is also performed for these heat-press molding.

The surface layer prepreg is produced by impregnating a glass fiber woven fabric with an epoxy resin and drying by heating, and the core layer prepreg is produced by impregnating a glass fiber nonwoven fabric with an epoxy resin containing an inorganic filler and drying by heating. The adjustment based on this is as follows. First, for the surface layer prepreg, the resin content was set to 40 to 50% by mass, and the adjustment of the resin curing degree was adjusted to 160%.
Gel time in stroke cure is 90-150
Do so in seconds. On the other hand, the core layer prepreg has a resin (including the blended inorganic filler) content of 87 to 93% by mass, and adjusts the degree of curing of the resin by heating and pressing the 100 mm square prepreg at 160 ° C. and 5 MPa. The molding is performed so that the resin flow at the time of molding becomes 15 to 40% by mass.

[0008] The specific control in the heat and pressure molding of the surface layer prepreg and the core layer prepreg is as follows. The pressure at the time of heating is controlled to increase from a primary pressure of 2 to 4 MPa to a secondary pressure of 5 to 10 MPa. This control is performed at the stage where the resin of the prepreg reaches the start of curing through the molten state. The pressure at the time of cooling after the heat and pressure molding is controlled to decrease from the secondary pressure to 0 to 1 MPa.

The reason why the above-mentioned prepreg adjustment and molding control reduce the warpage and twist of the composite laminate and improve the dimensional stability is presumed as follows.
In the production method according to the present invention, the surface layer prepreg has a higher resin content and lower resin curing degree than usual. The core layer prepreg has a higher resin content and a higher resin curing degree than usual. If the degree of resin curing of the core layer prepreg is increased, the resin flow at the time of heat and pressure molding is reduced.
This prevents the glass fiber nonwoven fabric from being cut or stretched due to the resin flow, reduces the residual internal stress caused by the resin flow, and contributes to the suppression of warpage and twisting of the laminate. Since the residual internal stress is a major cause of warpage and torsion, it is effective to reduce it.
In addition, increasing the resin content of the surface layer prepreg and lowering the degree of curing is advantageous in that the resin of the surface layer prepreg does not exert a large stress on the core layer prepreg during lamination molding, and the perforated portion of the core layer prepreg ( Voids) to completely fill the voids of the core layer prepreg. If the degree of curing is set low, the resin flow does not give a great stress to the core layer prepreg, which contributes to the suppression of warpage and twist of the laminate. The reason for increasing the resin content of the surface layer prepreg is to ensure that the voids of the core layer prepreg are filled with the resin of the surface layer prepreg and that a sufficient amount of resin is secured so as not to leave voids. Note that the reason for increasing the resin content of the core layer prepreg is the same, in order to reduce the perforated portion (void portion) of the core layer prepreg from the stage of prepreg.

[0010] The control of the heat and pressure forming in the production method according to the present invention contributes to remarkable improvement of dimensional stability in addition to suppression of warpage and twist of the laminated plate. By making the primary pressure lower than the secondary pressure, the flow of the resin in the surface layer prepreg and the core layer prepreg when the resin melts does not increase, and the flow during the resin melting does not become significant.・ It leads to suppression of torsion. The resin is raised from the primary pressure to the secondary pressure at a stage from the molten state to the start of curing to suppress the residual voids in the laminate and to secure the adhesive strength between the prepreg layers or between the metal foil and the surface layer prepreg. . At this stage, even if the pressure is increased, the flow of the resin is small, and there is no effect on warpage and twist. By lowering the pressure at the time of cooling after the heat and pressure molding from the secondary pressure to a pressure of 0 to 1 MPa, the stress remaining inside the laminate at the time of molding can be released, and no stress remains in the laminate. This leads to suppression of warpage and twist of the laminate. Also, during this cooling, the laminate tends to shrink, but by lowering to the low pressure, there are fewer obstacles when the laminate is about to shrink, and the laminate is released until the residual stress is released. Due to the sufficient shrinkage, the subsequent dimensional stability of the laminate is significantly improved.

As described above, in the production method according to the present invention, the prepreg used for the glass fiber woven fabric used for the surface layer and the prepreg used for the glass fiber nonwoven fabric used for the core layer of the surface layer are adjusted based on specific indices. The combination of the specific controls when these are heated and pressed and then cooled can suppress the warpage and twist of the composite laminate and ensure good dimensional stability.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In carrying out the method according to the present invention, the glass fiber woven fabric and the glass fiber non-woven fabric can be those which are commonly used for composite laminates. The epoxy resin to be impregnated into these is a bifunctional epoxy resin (such as bisphenol A epoxy resin), a trifunctional epoxy resin (such as bisphenol A epoxy resin with phenylglycidyl ether), and a polyfunctional epoxy resin (such as phenol novolac epoxy resin). And other epoxy resins can be appropriately selected alone or in combination. As the curing agent, a phenolic novolak resin, an amine compound or the like can be appropriately selected. Inorganic fillers such as aluminum hydroxide, magnesium hydroxide, and talc are added to the epoxy resin impregnated in the glass fiber nonwoven fabric as a filler. If necessary, an inorganic filler may be added to the epoxy resin impregnated in the glass fiber woven fabric. The epoxy resin may be blended with a flame retardant such as a bromo compound, antimony trioxide, antimony pentoxide, or a phosphorus compound, or a flame retardant aid to make the laminate flame-retardant. Aluminum hydroxide and magnesium hydroxide have not only a filler but also a flame retardant action. In the production of a composite laminate, a metal foil is integrally formed on the surface as necessary, but the metal foil is not particularly limited as long as it is suitable for wiring formation of a printed wiring board such as a copper foil, a nickel foil, and an aluminum foil. .

The surface layer prepreg and the core layer prepreg are each manufactured by impregnating a varnish of an epoxy resin composition diluted with a solvent into a long glass fiber woven fabric or a glass fiber nonwoven fabric while transferring the same, and drying by heating. I do. The adjustment of the resin content is performed by bringing a squeeze roll into contact with the impregnated glass fiber woven fabric or glass fiber nonwoven fabric. Adjustment of the degree of curing (semi-cured state, so-called B stage) of the prepreg resin is performed by the temperature and time of heating and drying. The resin content of the core layer prepreg is calculated by including the blended inorganic filler as a resin component. When the inorganic filler is included in the surface layer prepreg, the resin content is calculated in the same manner as in the core layer prepreg.

In the production of a composite laminate, a surface layer prepreg is laminated on both sides of one or more of the above core layer prepregs, and a metal foil is placed on both sides or one side if necessary. It is performed by heating and pressing between boards. The control for raising the primary pressure to the secondary pressure is performed at a stage where the resin of the prepreg reaches the start of curing through the molten state. However, it is difficult to directly know the state during the molding operation. By detecting the temperature, the state is indirectly grasped. The time when the pressure is increased is preferably when the temperature of the prepreg located in the center of the step of the press hot platen is in the range of 100 to 140 ° C.

[0015]

EXAMPLES Examples according to the present invention will be described in detail along with comparative examples and conventional examples. Examples 1 to 13, Comparative Examples 1 to 8 and Conventional Examples 80 parts by mass of bisphenol A type brominated epoxy resin ("YDB-400" manufactured by Toto Kasei), phenol novolak type epoxy resin ("YDPN-638" manufactured by Toto Kasei)
20 parts by mass, 3 parts by mass of dicyandiamide as a curing agent,
A varnish (A) was prepared by diluting 0.15 parts by mass of 2-ethyl-4-methylimidazole as a curing accelerator with methyl ethyl ketone. Further, a bisphenol A type epoxy resin which is liquid at room temperature ("Ep-82" manufactured by Yuka Shell Epoxy Co., Ltd.)
8 ") 66 parts by mass, tetrabromobisphenol A20
Parts by mass, 14 parts by mass of a phenol novolak resin ("TD-2093" manufactured by Dainippon Ink and Chemicals, Inc.) as a curing agent, 100 parts by mass of aluminum hydroxide, and 0.2 parts by mass of 2-ethyl-4-methylimidazole as a curing accelerator. Mix,
Varnish (B) was prepared. The varnish (A) Glass fiber woven fabric (Asahi Schwebel Ltd. "GC-7628", unit weight 210g / m ²⁾ was impregnated with, to obtain a surface layer prepreg by heating and drying. Further, the varnish (B) was impregnated into a glass fiber nonwoven fabric (“EPM-4090” manufactured by Japan Vilene, unit mass 90 g / m ² ) and dried by heating to obtain a core layer prepreg.

The properties of the surface layer prepreg and the core layer prepreg prepared as described above are as shown in Table 1. The gel time and resin flow shown in the table are measured as described below. Gelation time: The surface layer prepreg is cut into a predetermined size, rubbed, and 150 mg of resin powder is collected. This resin powder is stroke-cured on a hot plate (set at a surface temperature of 160 ° C.) of a gelling tester using a Teflon (registered trademark) rod.
The stroke is started at the same time as the resin powder is dropped on the hot plate, and the time from the time when the viscosity of the molten resin rises sharply to gelation is measured. Resin flow: Two 100 mm square test pieces are cut out from the core layer prepreg. The mass of the two test pieces is measured (initial mass). The two sheets are stacked, and release films are arranged on both sides thereof, and heated and pressed by a resin flow measuring press for about 10 minutes. The heating and pressurizing are performed at a temperature of 160 ° C. and a pressure of 5 MPa. After heating and pressing, the resin flowing around the test piece is removed, and the weight of the test piece is measured (final mass). The resin flow is determined by the following equation. Resin flow (%) = ((initial mass-final mass) / initial mass)
× 100

[0017]

[Table 1]

One surface layer prepreg is stacked on each side of the two core layer prepregs, and copper foil (1
(8 μm thick) was placed between the hot plates, and heated and pressed under predetermined conditions to produce a 1.6 mm-thick composite copper-clad laminate. The control of the heat and pressure molding is selected from the molding conditions 1 to 10 shown in Table 2.
The time for raising the pressure from the primary pressure to the secondary pressure is determined by the temperature of the prepreg during molding, and the temperature of the prepreg located in the center of the stage of the press hot platen is the temperature shown in each molding condition in Table 2. Is reached. Molding condition 4 shown in Table 2
Is the case where the pressure is increased from the primary pressure to the secondary pressure before the resin of the prepreg is melted. The molding condition 10 is a case where the pressure of the prepreg is increased from the primary pressure to the secondary pressure after the resin of the prepreg is cured through melting.

[0019]

[Table 2]

In each of the examples, comparative examples, and conventional examples, the combinations of prepreg types and molding conditions were performed as shown in Table 3.

Table 3 also shows the results of evaluating the properties of the composite copper-clad laminates manufactured in the respective examples. The evaluation method of each characteristic is as follows. Warpage: 34 from the composite copper clad laminate
Cut out a 0 × 250 mm size test piece. The copper foil on both surfaces of the test piece is etched with a ferric chloride aqueous solution to remove the entire surface.
Thereafter, an air heating treatment is performed at 150 ° C. for 30 minutes in a flat place. The test piece naturally cooled to room temperature is placed flat on a surface plate, and the lifting amount of the test piece at the four sides and four corners from the surface plate is measured with a gap gauge to determine the maximum value. The warpage amounts shown in Table 3 are average values of the maximum values measured for 100 samples. Dimensional change rate: From the manufactured composite copper-clad laminate,
A 340 × 250 mm size test piece is cut out. A hole having a diameter of 1.0 mm is formed in each of the four corners of the test piece at a position 10 mm inside from each side, and a distance between the holes is measured to obtain a normal dimension (L1).
Next, the copper foil on both surfaces of the test piece is etched with a ferric chloride aqueous solution to remove the entire surface. Then, at 150 ° C for 30 minutes,
Aerial heat treatment is performed on a flat surface. The dimension between the holes of the test piece naturally cooled to room temperature was measured, and the dimension after heat treatment (L
2). The dimensional change is calculated by the following equation. The dimensional change rates shown in Table 3 are average values for 10 samples. Dimensional change rate (%) = ((L1−L2) / L1) × 100 Appearance after etching: A 340 × 250 mm size test piece is cut out from the manufactured composite copper-clad laminate. The copper foil on both surfaces of the test piece is etched with a ferric chloride aqueous solution to remove the entire surface. Thereafter, the laminate surface and the cut surface are observed. Thickness difference: The thickness of the manufactured composite copper-clad laminate having a size of 1000 × 1000 mm is measured, and the difference between the maximum value and the minimum value is determined as the thickness difference. The thickness difference shown in Table 3 is an average value for 10 samples.

[0022]

[Table 3]

Comparative Example 1 shows a case where the resin content of the surface layer prepreg is too small, and Comparative Example 2 shows a case where the resin content of the surface layer prepreg is too large. Comparative Example 3 shows a case where the resin flow of the core layer prepreg is too small, and Comparative Example 4 shows a case where the resin flow of the core layer prepreg is too large. Comparative Example 5
The case where the pressure is increased from the primary pressure to the secondary pressure before the prepreg resin is melted (the pressure increase timing is too early) is shown. In Comparative Example 6, the primary pressure is increased after the prepreg resin is cured through melting. From the pressure to the secondary pressure (the pressure rising timing is too late). Comparative Example 7 shows a case where the primary pressure is too small, Comparative Example 8 shows a case where the primary pressure and the secondary pressure are too large, and Comparative Example 9 shows a case where the cooling pressure is too large.

[0024]

As is clear from Table 3, the composite laminate manufactured by the method according to the present invention has reduced warpage and twist and good dimensional stability. And the base material runs out,
There are no defects such as blurring and voids, and the thickness accuracy is good. By providing such a composite laminate for the manufacture of printed wiring boards, troubles in the printed wiring board processing process, which had been a problem due to the occurrence of warpage and torsion and insufficient dimensional stability, were reduced, The yield and cost can be greatly improved.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08J 5/24 CFC C08J 5/24 CFC H05K 3/00 H05K 3/00 R // H05K 3/46 H05K 3/46 G B29K 63:00 B29K 63:00 105: 08 105: 08 105: 16 105: 16 B29L 9:00 B29L 9:00 C08L 63:00 C08L 63:00 F term (reference) 4F072 AA04 AA05 AA07 AA09 AB09 AB28 AD23 AD27 AD28 AE02 AE06 AF03 AF27 AG03 AH02 AH25 AJ04 AK05 AK14 AL09 AL12 4F100 AA01B AG00A AG00B AG00C AK53A AK53B AK53C BA03 BA06 BA10A BA10C CA23B DG12A DG12C DG15B DH01A DH01B DH01C EJ42A EJ42B EJ42C EJ82A EJ82B EJ82C EJ86A EJ86B EJ86C GB43 JL04 4F204 AA39 AB11 AD16 AG03 AR03 AR06 AR11 FB01 FG09 FN15 5E346 AA02 AA12 AA51 CC01 CC09 DD02 EE01 EE09 EE13 EE18 GG28 HH11

Claims (2)

[Claims] 1. A prepreg impregnated with an epoxy resin in a glass fiber woven fabric and heated and dried as a surface layer, and a prepreg impregnated with an epoxy resin containing an inorganic filler in a glass fiber nonwoven fabric and heated and dried as a core layer of the surface layer, In the production of a composite laminate in which these are heated and pressed between press hot plates, the surface layer prepreg has a resin content of 40 to 50% by mass, and the degree of resin curing is adjusted by a gelation time at 160 ° C. stroke cure. The core layer prepreg is made of a resin (including a blended inorganic filler).
The content is set to 87 to 93% by mass, and the adjustment of the resin curing degree is performed.
The 100 mm square prepreg is heated and pressed at 160 ° C. and 5 MPa so that the resin flow is 15 to 40%. The heat and pressure forming of the surface layer prepreg and the core layer prepreg is performed during heating. From a primary pressure of 2-4 MPa to 5-1
Control to increase the secondary pressure to 0 MPa and control to reduce the pressure at the time of cooling after heating and pressing from the secondary pressure to 0 to 1 MPa, and control to increase the primary pressure to the secondary pressure At a stage where the resin of the prepreg passes through a molten state and starts to cure. 2. The control for increasing the primary pressure to the secondary pressure by adjusting the prepreg temperature at the center of the press hot platen to 100-140.
The method for producing a composite laminate according to claim 1, wherein the method is carried out when the temperature is at ° C.