JPS61287744A - Method of molding laminated board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming multilayer printed wiring boards and laminates such as copper-clad laminates and non-copper-clad laminates.

Conventional Technology Conventionally, the hot platen press method has been generally known as a technique for laminating and forming plates used in multilayer printed wiring boards and laminates such as copper-clad laminates and non-copper-clad laminates used in multilayer printed wiring boards. It is being

This hot platen press method involves stacking a large number of materials to be formed to be used for the above-mentioned laminates between hot plates via a plurality of plate molds (mirror plates), and then applying heat and pressure to form the materials. The resin part of the prepreg is once softened and then hardened to bond and mold the material to be molded.

Problems to be Solved by the Invention However, this method has the following problems.

The prepreg used for laminates is molded under heat and pressure while containing some moisture, air during lamination, air contained in the coated paper fabric, and volatile substances from unreacted resin raw materials as air bubbles. , voids occur inside the laminate, significantly degrading the properties of the laminate.

Therefore, in order to eliminate the air bubbles, attempts have been made to make the impregnated resin softened by heating flow and push out the air bubbles contained in the prepreg, but the edges (periphery) of the prepreg do not radiate heat. The heating temperature will be lower. On the other hand, the central part of the prepreg accumulates heat and the heating temperature becomes high, and the molten viscosity of the impregnated resin is low, and the molten resin of the prepreg flows out due to the high pressure (generally about 40 kg/fan) from the hot plate and the edges of the laminate. The thickness of the center part is thinner than that of the center part.

In addition, the resin that flows out hardens and becomes flaky and adheres to the press, heating plate, and plate mold, causing problems during secondary molding and leaving dents in the laminate, resulting in poor appearance.

Therefore, conventionally, Japanese Patent Application Laid-Open No. 121734/1983.

Although various improvements have been made as shown in JP-A-59-62113, JP-A-59-76257, etc.
Each has advantages and disadvantages, and appropriate improvement measures are desperately needed.

Means for Solving the Problems In the method for forming a laminate according to the present invention, when forming a laminate, the material to be formed to form the laminate is placed in a side pressure prevention member on a platen, and the material to be formed is placed in a lateral pressure prevention member on a platen. After covering and sealing the molded material with a vacuum bag film and storing it in a pressure vessel and sealing it,
The method is characterized in that the pressure inside the vacuum bag film is reduced, and high-pressure gas is supplied into the container, and the gas is heated to heat and pressurize the material to be formed to harden the adhesive.

Example Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

First, prior to the explanation, the laminate as used in the present invention will be explained.

The laminate used in the present invention refers to a multilayer printed wiring board and a copper-clad laminate used for the multilayer printed wiring board.

Refers to a laminate such as a non-copper-clad laminate (for example, an aluminum-clad laminate), and the material to be formed into which the laminate is laminated includes the copper-clad laminate, non-copper-clad laminate, prepreg, copper foil, etc. There is.

Prepreg is made by impregnating a base material such as paper or glass cloth with thermosetting resin varnish such as phenolic resin varnish or epoxy resin varnish to create a resin-impregnated sheet, and then drying this resin-impregnated sheet to create a B-stage. .

Copper-clad laminates are made by cutting the prepreg into regular dimensions.

It is made by stacking a plurality of prepregs, pasting copper foil on one or both sides of the prepreg, and applying heat and pressure to adhesively cure and mold.

A multilayer printed wiring board, for example, is one in which a single-sided copper-clad laminate, a prepreg, an inner-layer circuit board, a prepreg, and a single-sided copper-clad laminate are laminated in sequence, heated and pressed, and adhesively cured and molded.

Furthermore, special terms used in the present invention will be explained.

A vacuum bag film is a heat-resistant yet flexible film that isolates a material to be molded from the outside and brings it into close contact with the material by vacuum pressure. Generally, plastic films such as nylon 6, nylon 66, and polytetrafluoroethylene are used.

A breather is a device that maintains a uniform pressure load by allowing air and gas (bubbles) generated by reaction to pass through even when the pressure is reduced within the vacuum bag film and pressure is applied to the container.

Heat-resistant glass cloth is used.

A sealant is used to attach the material to be formed to a jig (in this case, a platen).
It completely seals against the mold and ensures hermeticity during molding.
Generally, a sticky clay-like substance is used.

A platen is a plate-shaped jig that stacks materials to be formed and receives pressure from the upper surface of the materials to be formed.In general, the platen has a flat surface that is less distorted by heating and has a smooth upper surface. A flat plate made of light metal is used.

Next, the configuration of the embodiment will be explained.

As shown in Figures 1 and 2, ■ indicates a copper-clad laminate.

Molded materials such as inner layer circuit boards, prepregs, and copper foils.

Reference numeral 2 represents a pressure vessel for accommodating the material to be formed, and reference numeral 3 represents an opening/closing door for sealing the container 2.

A is a heating and cooling means that heats and cools the material to be formed contained in the container 2.

B is a high-pressure gas supply means for supplying high-pressure gas (for example, high-pressure nitrogen, high-pressure carbon dioxide, high-pressure air, etc.) into the pressure vessel.

C is a heated gas heated by a heat exchanger (for example, high-pressure nitrogen gas heated by high-pressure steam).

high-pressure carbon dioxide, high-pressure air, etc.) and cooling gases (e.g. high-pressure nitrogen gas cooled by cooling water).

High pressure carbon dioxide gas, high pressure air, nitrogen gas, carbon dioxide gas.

This is a circulation means that blows and circulates air, etc.) to the molded material 1 in the container 2.

D is a pressure reducing means for reducing the pressure inside the container 2 and the vacuum bag film.

E is a container which has a plurality of sheets of the material to be formed 1 placed on a platen, a lateral pressure prevention member arranged therein, a means for covering and sealing the material to be formed with a vacuum bag film, and reducing the pressure inside the vacuum bag film. This is a member for equipping the material to be formed, which is provided so as to be able to move in and out of the 2.

F is a lateral pressure prevention member provided to surround the material to be formed 1 placed on the platen, and prevents pressure from being applied to the side surface of the material to be formed 1 when high pressure gas is supplied into the container 2. be.

Next, details of each means and each member will be explained.

“The heating and cooling means A is configured to supply high pressure steam from the outside of the container 2 to the internal heat exchanger 4 as shown in FIGS. 1 and 2, and includes an automatic valve 5 that supplies high pressure steam An automatic valve 6 for supplying cooling water is provided through the container 2 and communicated with the heat exchanger 4, and an automatic drain valve 7 is provided in communication with the lower part of the container 2 from below the heat exchanger. It is.

The high pressure gas supply means B stores, for example, 14 kg/- in the container 2.
An automatic valve 8 for supplying high-pressure gas such as high-pressure nitrogen gas, high-pressure carbon dioxide gas, or high-pressure air is provided in communication with the automatic valve 8 for supplying high-pressure gas such as high-pressure nitrogen gas, high-pressure carbon dioxide gas, or high-pressure air. The air is then exhausted through the automatic valve 9. Furthermore, a safety valve 10 is provided to reduce the pressure inside the container 2 when it exceeds a predetermined pressure.

In addition, as another example of the heating and cooling means, a means for heating and cooling may be provided outside the container 2, and the heating gas and cooling gas may be supplied to the container 2.

The circulation means C includes a fan 12 provided inside the container 2, and a motor 13 for driving the fan installed outside the container 2 so as to be airtight. and,
The heating gas and cooling gas sent by the fan 12 pass through the outer periphery of the wind barrel plate 14 shown in FIG. It consists of

In this manner, the heated gas passes over the surface of the material to be formed, thereby heating the material to be formed.

The pressure reducing means branches off from a vacuum pump 16 installed outside the container 2, as shown in FIGS. 1 and 2.

The pipes are connected to the inside of the container 2 via an automatic valve 17 and an automatic valve 18, respectively. One of the branched pipes serves as a means for reducing the pressure inside the container 2.

The other end is connected to each platen 21 or the side pressure prevention member F so that it can be attached to and removed from the pipe in order to reduce the pressure inside the vacuum bag film 20.

As shown in FIGS. 1 and 2, the forming material equipment member E includes a multi-stage shelf 24 placed on a trolley 23, and an iron fence connected to the platen 21.
can be inserted and taken out, and furthermore, the cart is provided so that it can be carried into and taken out of the container 2.

A lateral pressure prevention member F as shown in FIGS. 4 and 6 is installed on the platen 21, and in the lateral pressure prevention member,
The materials to be formed 1 are stacked and placed on the platen 21 . For example, as shown in FIG. A mirror plate 26 is placed, followed by a copper foil 27. A plurality of sheets of prepreg 28, copper foil 27. Mirror plate 26. The cushioning material 29 is layered one after another, and the mirror plate corresponds to the plate mold described above, and generally has a thickness of 1.0 to 2.0.
It is a flat plate made of stainless steel with a diameter of about mm.

Next, the laminated materials to be formed are covered with, for example, a vacuum bag film 20, as shown in FIG.

As shown in FIG. 7, the platen 21 or side pressure prevention member F
A sealant 30 is attached to the outer periphery of the sealant 3.
0 is provided so that the outer periphery of the vacuum bag film 20 can be adhered to seal the laminate, which is the material to be molded 1. Then, the air inside the vacuum bag film 20 is removed by the breather 25. It passes through a vacuum path provided in the platen 21 or the side pressure prevention member F, and is provided so as to be able to communicate with and shut off from the aforementioned pressure reducing means.

The side pressure prevention member F is provided so as to surround the material to be formed placed on the platen 21, and when high pressure gas is supplied into the container 2, the pressure on the stacked materials to be formed is reduced by the vacuum bag film 20. Pressure is only applied from the top surface through the side pressure prevention member, and pressure is not applied from the side side because it is blocked by the partition wall of the side pressure prevention member.

FIG. 4 shows a first embodiment of the side pressure prevention member. The lateral pressure prevention member in this case consists of a rectangular frame 32 with open upper and lower surfaces and a flat plate 33 that can fit into the upper opening of the frame.The method for loading and sealing the material to be formed is shown in FIG. An appropriate gap is provided between the material to be formed 1 and the inner wall of the frame 32 of the side pressure prevention member, and the material to be formed 1 is covered with a vacuum bag film 20 and sealed with a sealant 30.

The lateral pressure prevention member F is provided with a vacuum path 34 for reducing the pressure inside the vacuum bag film 20, and is provided so that it can be connected to and removed from the vacuum pump 16 via an automatic valve 18 shown in FIGS. 1 and 2. .

FIG. 6 shows a second embodiment of the side pressure prevention member. In this case, the lateral pressure prevention member is a rectangular box 35 with an open bottom, and the method for loading and sealing the material to be formed is as shown in FIG. In addition, an appropriate gap is provided between the material to be formed 1 and the inner wall of the rectangular box 35 of the lateral pressure prevention member, and the material to be formed 1 is covered with a vacuum bag film 20 and sealed with a sealant 30. . In this case, the vacuum path 34 is connected to the platen 21
It is set up in

When high-pressure gas is supplied into the container 2 and the gas is heated to heat and pressurize the material to be formed, the inside of the container becomes static pressure, so pressure is applied from all directions indicated by the arrows in Figure 5. It will be done.

However, since the lateral pressure prevention member F receives the lateral pressure, no lateral pressure is applied to the workpiece 1 within the lateral pressure prevention member, and the workpiece 1 is pressed onto the platen 21 with pressure only from the upper surface. work.

Next, its effect will be explained.

First, the material to be formed 1 for forming a laminate on the platen 21 is sequentially stacked in multiple layers, for example, as shown in FIG. The molded material 1 is sealed by covering it with a sealant 30 and adhering it onto the platen 21 with a sealant 30. next,
The material to be formed 1 is placed on the shelf 24 of the cart 23, and as shown in FIGS.
As shown in the figure, it is carried into the container 2, one side of the pipe branched from the vacuum pump 16 is connected to a removable coupler 37 provided on the side surface of the side pressure prevention member F, and the door 3 is closed.

Next, the vacuum pump 16 is activated, followed by the automatic valve 17.
18 to remove the inside of the container 2 and the vacuum bag film 2.
Reduce the pressure within 0. Here, when air is used as the high pressure gas, there is no need to reduce the pressure inside the container 2.

Finally, the automatic valve 17 is closed to stop the pressure reduction inside the container 2.

Next, while reducing the pressure inside the vacuum bag film 20, the automatic valve 8 is operated to supply high-pressure gas into the container 2, and the automatic valve 5 is operated to supply high-pressure steam to the heat exchanger 4 inside the container 2. supply.

The high pressure gas is heated. Next, by driving the motor 13 and rotating the fan 12, the heated high-pressure gas is circulated through the molded material 1 of the side pressure prevention member F via the outer periphery of the wind barrel plate 14.

Then, the material to be formed 1 is heated and pressurized.

At this time, pressure is applied to the material to be formed 1 from the top and side surfaces as shown by the arrows in FIG.

As mentioned above, the side pressure is received by the frame 32 of the side pressure prevention member,
The material to be formed 1 will be added only from the top.

Furthermore, since the gap 38 between the molded material 1 and the lateral pressure prevention member F is depressurized and becomes a high vacuum, the heating to the molded material 1 is applied from the side surface of the frame 32 to the side surface of the molded material 1. No heat transfer takes place. Therefore.

There is no heat radiation from the side surfaces of the material to be formed 1, and heat is stored by heating from the top and bottom surfaces.

Then, the material to be formed is heated to a temperature at which the resin portion of the prepreg of the material to be formed softens and the melt viscosity becomes a minimum value, and this temperature is maintained for a while. At this time, as described above, the ends of the prepreg accumulate heat and the temperature difference with the center becomes smaller.

The melt viscosity at the center and end portions of the prepreg is approximately the same.

Then, when the middle part (middle layer part) of the laminated materials to be formed is melted and reaches the minimum viscosity, the pressure is increased and the temperature is raised as shown in FIG. Due to this pressure increase, the air bubbles contained in the prepreg are pushed out to the end (periphery) and discharged into the vacuum in the gap between the side pressure prevention members F.

In addition, in the present invention, the pressure increase is not as high as about 40 kg/cffl used in the conventional hot platen press method, but is generally a low pressure of about 20 dazzle/ci or less, or depending on the conditions, 10 kg/crd or less. However, it can be fully functional.

One reason for this is that in the case of the present invention, since static pressure is applied, it can be applied uniformly to the upper surface of the material to be formed.

Unlike the hot platen press method, there is no heat dissipation from the edges (periphery) of the material to be formed, and the melt viscosity at the center and edges of the prepreg is almost the same, improving fluidity, so it can be encapsulated in the prepreg even at low pressure. It is possible to sufficiently push out the air bubbles that are present.

Next, according to the program shown in FIG. 8, the resin part of the prepreg is heated at a specified temperature for curing (for example, in one embodiment of the present invention, epoxy resin is used, so the specified temperature is 170°C), and the pressure is increased for a certain period of time. Heating takes place.

When the adhesive hardening of the molded material 1 is completed, the automatic valve 5 shown in FIG. 1 is operated in reverse to stop the supply of high-pressure steam. next,
The automatic valve 6 is operated to supply cooling water to the heat exchanger 4 to cool the gas circulating in the container 2, and the automatic valve 9 is operated to gradually lower the pressure inside the container 2.

When the temperature of the material 1 to be formed reaches a level that an operator can handle, all operations are stopped, the door 3 is opened, and the material 1 to be formed is carried out to the outside, completing one process.

Here, the dimensions of the two-layer copper-clad laminate: 500mm x 500mm
.

When prepreg G-10 was molded according to the conditions shown in FIG. 8, there was no flash at the end of the laminate.

A two-layer copper-clad laminate with uniform thickness and no voids was obtained.

9. The molding program used in the present invention is under conditions other than those shown in FIG. 82. For example, the type and size of the prepreg resin,
It varies depending on the number of layers to be laminated.

The present invention is not limited to the embodiments.

Effect of the invention According to the present invention, the following effects are achieved.

In forming a laminate, the material to be formed forming the laminate was placed in a lateral pressure prevention member on a platen, the material to be formed was covered and sealed with a vacuum bag film, and the material was placed in a pressure vessel and sealed. After that, the pressure inside the vacuum bag film is reduced, and high pressure gas is supplied into the container and the gas is heated to heat and press the molded material to harden the adhesive, so that the inner wall of the side pressure prevention member and the molded material are The gap between the prepreg and the prepreg becomes a vacuum and no heat conduction takes place, and the ends of the prepreg accumulate heat, reducing the temperature difference between the center and the ends of the prepreg.Moreover, since the prepreg is pressurized at a low pressure, it softens due to heating. The impregnating resin can be made to flow uniformly and easily from the center to the ends, and therefore the air bubbles contained in the prepreg can be easily discharged, making it possible to create a material with no voids and a uniform thickness. A laminate can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway schematic side view showing one embodiment of the device according to the present invention. FIG. 2 is a schematic vertical sectional view of the apparatus shown in FIG. 1. FIG. 3 shows an embodiment of a laminated plate in which materials to be formed are stacked in two layers. FIG. 4 is a three-dimensional view showing the first embodiment of the side pressure prevention member. FIG. 5 is a sectional view showing a state in which the material to be formed and the side pressure prevention member of the first embodiment are placed on a platen and covered and sealed with a vacuum bag film. FIG. 6 is a three-dimensional view showing a second embodiment of the side pressure prevention member. FIG. 7 is a sectional view showing a state in which the material to be formed and the side pressure prevention member of the second embodiment are placed on a platen and covered and sealed with a vacuum bag film. FIG. 8 is a diagram showing an example of a heating and pressing program for molding a material to be molded. In these figures, A: heating and cooling means, B: high-pressure gas supply means, C6 circulation means, D: decompression means, and E: forming material equipment member. F Side pressure prevention member, 1: Molded material, 2: Pressure vessel. 3: Door, 4/Heat exchanger, 5, 6, 7, 8, 9: Automatic valve, 1o: Safety valve, 12: Fan, 13: Motor, 14:
Wind body board, 16. Vacuum pump, 17.18 Automatic valve, 2o
: Vacuum bag film, 2 platen, 23: Trolley, 2
4: Shelf, 25: Breather, 26: Mirror plate, 27: Copper foil,
28 Niblibreg, 29. Cushion material, 3o nitrogen. 32: Frame, 33: Flat plate, 34: Vacuum path, 35: Square box, 37: Cover, 38: Gap. Figure 1 Figure 82 Group 4

Claims (1)

[Claims] In forming a laminate, the material to be formed forming the laminate was placed in a lateral pressure prevention member on a platen, the material to be formed was covered and sealed with a vacuum bag film, and the material was placed in a pressure vessel and sealed. Thereafter, the pressure inside the vacuum bag film is reduced, and high-pressure gas is supplied into the container and the gas is heated to heat and pressurize the material to be molded to cure the adhesive.