JP2005317730A - Method for manufacturing substrate for printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a substrate for a printed wiring board in which temperature control whose temperature raising speed is 4C° per minute is performed even when heated steam is used as a heat source. <P>SOLUTION: When a plurality of laminated constitution bodies formed by stacking a prepreg and metal foil in this order from inside are stacked on both the surfaces of an internal layer circuit board, sandwiched between press heat boards using steam as a heat source, and heated, and pressed into one body; initial heating is intermittent heating in which injection of steam of 100 to 140°C and its stop are repeated not to heat the pressed body above proper temperature, and the gradient of a rise in product temperature of the pressed body is set to ≤4°C per minute. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a printed wiring board substrate.

  Laminated structure in which a prepreg and a metal foil (usually copper foil) that are semi-cured and impregnated with resin are impregnated in this order from the inside on both sides of the core board (inner circuit board) on which the circuit is formed 2. Description of the Related Art Conventionally, a printed wiring board substrate manufacturing method (ie, a method using a multistage press) in which a plurality of sets of bodies are stacked, sandwiched between press hot plates, and integrated by pressing and heating is known. (See Patent Documents 1 and 2). The multilayer printed wiring board is formed by forming a circuit on the surface of the printed wiring board substrate manufactured by the above method, and alternately superimposing the circuit board and the prepreg, sandwiching them between press hot plates, and heating and pressurizing them. To manufacture.

A metal plate (such as iron) is usually used as the press hot platen, and in the metal plate, a heat medium such as heated steam or heated oil (or a coolant such as water) serving as a heat source is used. A passage is formed, and the press hot platen is pressurized with hydraulic pressure or the like.
In addition, when heating steam is used as a heat source, there are some changes depending on the type of thermosetting resin in the pressed product, but about 100 to 130 ° C. in the initial heating (starting operation to about 1 hour). Followed by continuous injection of steam at about 180 ° C. in the middle (approximately 1-2 hours of operation) and late (approximately 2-3 hours of operation) heating. Often to do.

  By the way, in the case of steam in which the heat source is continuously injected (supplied), control at a temperature of 100 ° C. or less is almost impossible. Therefore, when it is necessary to control the temperature rise at 100 ° C. or lower, usually other means such as heated oil is used as the heat source.

Japanese Patent No. 2990825 Japanese Patent No. 3428480

  In the case of the above method using heated steam as a heat source, even if the temperature of the press hot platen, the pressure applied between the press hot plates and the operation time are appropriately set according to the type of thermosetting resin in the pressed object, etc. In the initial heating from the start of operation to 120 ° C., it is difficult to control the temperature increase rate of the pressed object to 4 ° C. or less, and it tends to be overheated. In addition, the thermosetting resin material of the printed wiring board substrate is softened at around 80 to 130 ° C. and often melts depending on the material. If the temperature rise rate in the initial heating is too fast, the melt viscosity of the pressed material decreases. After that, the resin in the prepreg melts and flows with pressurization and becomes distorted, and dimensional change is likely to occur. In order to avoid these problems, the temperature must be controlled so that the rate of temperature rise is 4 ° C. or less. The objective of this invention is providing the manufacturing method of the board | substrate for printed wiring boards which temperature-controls a temperature increase rate to 4 degrees C / min or less even if it uses heating steam as a heat source.

In order to achieve the above object, the inventors have made various studies and completed the present invention.
That is, the present invention is a laminate in which a prepreg and a metal foil (usually a copper foil) are stacked in this order from the inside on both surfaces of an inner layer circuit board (a fibrous base material is impregnated with a resin and is semi-cured). When stacking multiple sets of components, sandwiching them between press hot plates using steam as a heat source, and integrating them by heating and pressurization, the initial heating will not heat the pressed object beyond the appropriate temperature. In addition, it is intermittent heating in which steam injection at about 120 ° C. (100 to 140 ° C.) is repeated and stopped, and the gradient of the product temperature rise of the pressed product is 4 ° C./min or less. The present invention relates to a method for manufacturing a substrate.
The present invention also relates to the above-described printed wiring board manufacturing method, wherein the number of repetitions of steam injection and stoppage is at least once.
Moreover, this invention relates to the manufacturing method of said printed wiring board board | substrate whose steam injection time is 1 to 5 minutes.

  According to the present invention, in the initial heating, heating steam is intermittently injected (supplied) into the press hot platen, so that the temperature rise rate is gradually increased without causing overheating, and the pressed object is brought to an appropriate temperature. Can be heated.

According to the present invention, even when heated steam is used as a heat source, the temperature rise rate in initial heating is not too fast (without becoming overheated), and the substrate for a printed wiring board that controls the temperature rise of the pressed object to 4 ° C. or less per minute We were able to provide a manufacturing method. Accordingly, it is possible to provide a printed wiring board substrate that prevents molding defects such as strain and dimensional change of the printed wiring board substrate.
In addition, it is possible to cope with the diversification of printed circuit board materials in recent years, for example, the use of high-performance resin materials and the configuration having IVH by a method other than plating, and manufacturing printed circuit board substrates. it can.

The present invention will be described in further detail.
The heating process performed together with the pressurization in the production of the printed wiring board substrate of the present invention includes initial heating, intermediate heating, and final heating, followed by a cooling process. As described above, the present invention is characterized by the method of initial heating.

  The number of repetitions of the steam injection and the stop in the initial heating is selected so that the temperature rise rate of the pressed object is a temperature not exceeding 4 ° C. per minute. It is at least once, preferably 1 to 5 times, more preferably 2 to 3 times.

  In addition, the time for steam injection and the time for stopping steam injection in the initial heating are related to the size of the multistage press and the size of the hot platen (metal plate), but the temperature rise rate is not too fast. Select the “steam injection time” and “steam injection stop time” that change to (temperature rise). Although it may be determined appropriately by experiment, it is preferable that the steam injection time is 1 to 5 minutes and the steam injection stop time is 10 to 60 minutes. It is important to stop steam injection before the temperature of the entire hot plate rises to a temperature corresponding to the steam pressure. Thereby, the hot platen temperature can be increased more slowly (than continuous steam injection).

  When it is necessary to further increase the hot platen temperature by the second steam injection in the initial heating, the steam is not injected continuously at a considerable steam pressure, but the second steam is injected and then the steam is injected again. To stop. The same applies to the third steam injection in the initial heating.

  In the medium-term heating, after the final steam stop in the initial heating, steam having a predetermined steam pressure is injected, and the steam is continuously injected and raised to the curing temperature (molding temperature). The reason why the steam injection stop time is sandwiched between the last steam injection in the initial heating and the continuous steam injection in the medium heating is as follows. That is, the injected steam becomes water with time and remains in the hot platen, which tends to be an unstable factor during subsequent steam reinjection. After this last steam injection, the steam injection is temporarily stopped to remove residual water in the hot platen which becomes an unstable factor. Thereby, continuous steam injection in the medium-term heating can be stably performed. The time from the end of the last steam injection in the initial heating to the start of continuous steam in the medium heating depends on the size of the heating plate and the length of the steam path, but preferably 40 minutes so as not to exceed 60 minutes. Do not exceed.

  In addition, when the rate of temperature increase is excessively increased by continuous steam injection in medium-term heating, this can be suppressed by lengthening the last steam injection in initial heating. In addition, in order to actually set the temperature of the pressed product to the desired temperature rise curve, the thickness and material of the cushion material sandwiched between the pressed product and the press heating platen are selected, and combined with the pressing conditions, the optimum multistage press It is also important to drive the machine.

The following examples illustrate the invention.
Example 1

As the material to be pressed, prepreg (GEA-67N, manufactured by Hitachi Chemical Co., Ltd.) and copper foil (electrolytic copper foil, thickness) on both sides of the inner layer circuit board (MCL-E-67, manufactured by Hitachi Chemical Co., Ltd.) 18 μm) were stacked in this order from the inside to prepare a plate material having four conductor layers. 20 sheets of these are overlapped with a stainless steel mirror plate, heat-resistant cushions are placed above and below, inserted between the press hot plates, heated and pressurized with the program setting of the heat source temperature shown in FIG. A substrate was manufactured. The program setting of the heat source temperature is as shown in FIG. 1. In the initial heating, the first steam injection is 3 minutes, the subsequent stop time is 30 minutes, the second steam injection is 3 minutes, and then The stop time is 30 minutes, and in the mid-term heating, the temperature is linearly increased from 110 ° C. to 185 ° C. for about 45 minutes by continuous injection of steam. Further, the latter heating is about 65 minutes and is a constant temperature heating of about 185 ° C.
The temperature transition of the pressed product is shown in FIG. The second axis on the right side shows a temperature increase gradient every 30 seconds, and it can be seen that the initial heating is suppressed to 4 ° C. or less per minute.
Example 2

A printed wiring board substrate was manufactured by heating and pressurizing in the same manner as in Example 1 except that the program was set for the heat source temperature shown in FIG. The program setting of the heat source temperature is as shown in FIG. 2. In the initial heating, the first steam injection is 3 minutes, the subsequent stop time is 63 minutes, and the second steam injection is continuous steam injection. Then, the stop time is 63 minutes, and in the mid-term heating, the temperature is linearly increased from 110 ° C. to 185 ° C. for about 45 minutes by continuous injection of steam. Further, the latter heating is about 65 minutes and is a constant temperature heating of about 185 ° C.
The temperature transition of the pressed product is shown in FIG. In the initial heating, the temperature gradually rises from about 30 ° C. at the start to about 60 ° C. after 40 minutes, but has a constriction around 60 ° C. in the initial period of the medium-term heating. Although the temperature rises, the slope is kept at 4 ° C. or less per minute. In addition, when Example 1 and Example 2 are compared, the temperature transition of the to-be-pressed goods of Example 1 is more preferable.

It is a graph of the program setting value of heat source temperature in the manufacturing method of Example 1 of this invention. It is a graph of the program setting value of heat source temperature in the manufacturing method of Example 2 of this invention. It is a graph which shows the temperature transition and temperature rising inclination of the to-be-pressed material in Example 1 and Example 2. FIG.

Claims (3)

Two or more sets of laminated structures in which prepreg and metal foil are stacked in this order from the inside are stacked on both sides of the inner layer circuit board, and are sandwiched between press hot plates that use steam as a heat source, and then heated and pressurized to integrate To
The initial heating is intermittent heating in which steam injection at 100 to 140 ° C. and the stop thereof are repeated so as not to heat the pressed material beyond the appropriate temperature, and the gradient of the product temperature rise of the pressed material is 4 ° C. per minute. A method for producing a printed wiring board substrate, comprising: The method for producing a printed wiring board substrate according to claim 1, wherein the number of repetitions of the steam injection and the stop thereof is at least one. The method for producing a printed wiring board substrate according to claim 1 or 2, wherein the steam injection time is 1 to 5 minutes.

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