JPH0453168B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a multilayer printed wiring board and an apparatus used in manufacturing the multilayer printed wiring board. (Prior Art) Generally, a multilayer printed wiring board is manufactured as follows. A suitable number of substrates on which a predetermined pattern (conductor circuit) has been formed by etching a copper-clad laminate and an uncured resin-impregnated base material (prepreg) that can bond these substrates to each other are alternately laminated,
These laminated substrates and base materials are integrated by pressurizing and hot pressing. This pressing is performed to prevent gas from remaining between the substrates and base materials, and this pressing is an absolutely necessary operation. However, since this press is performed under high pressure of 40 to 50 kg/ ^cm2 , a large amount of resin may flow out at the end of the process, making it impossible to secure the desired thickness for the multilayer printed wiring board. Or, adhesion between each layer may not be obtained and the layers may become loose. In other words, a board with a conductor circuit has a convex portion corresponding to the thickness of the conductor circuit, while a base material for insulating and bonding between boards is generally formed by impregnating resin into glass fibers. It has been done. Therefore, if both are placed in a sanderch state and pressed under high pressure, the resin will move to both sides of the base material that contacts the conductor circuit on the board side, leaving behind the glass fibers that make up the base material, which will cause the conductor circuit to This weakens the adhesive effect of the resin in the areas where it exists. In particular, when conductor circuits are present in high density to enable high-density packaging, as in recent multilayer printed wiring boards, the above-mentioned adhesive effect becomes extremely small, resulting in so-called delamination phenomena. This may also result in defects. Further, stress may remain in the base material etc. due to this pressing, resulting in problems such as "warping" in the multilayer printed wiring board formed in this way. In order to solve such problems, there has conventionally been an "autoclave" method shown in FIG. 3 or a "daylight" method shown in FIG. 4. The "autoclave" is a sealed and depressurized pack by covering a laminated printed wiring board 71 with a heat-resistant sheet 72 and sealing the periphery of the heat-resistant sheet 72 on a surface plate 73 with only a heat-resistant resin. Then, store this pack in an airtight container 74 weighing 10 to 20 kg/
A multilayer printed wiring board in which a large number of substrates are laminated is made by heating and pressing with an inert gas (for example, nitrogen) of cm ² . On the other hand, when "Daylight" presses a laminated printed wiring board 81 between heat platens 82, a wall 83 made of a flexible material such as rubber is placed around the printed wiring board 81 to form an airtight state. This is a method of standing up. In this method, the top and bottom of the wall 83 are sealed with a thermal platen 82, and the thermal platen 82
Pressing is performed at a low pressure of 10 to 20 kg/cm ² by discharging gas from an exhaust port formed in the wafer. (Problem to be Solved by the Invention) However, in the case of the above-mentioned "autoclave", unlike pressing using a hot platen, the curing of the resin does not necessarily occur from the center of the printed wiring board, but may occur from the periphery. It was hot. If the curing of this resin occurs from the periphery of the printed wiring board, or if it occurs from the periphery of the printed wiring board at the center, the air bubbles located at the center will completely disappear even though the pressure has been reduced. A problem had arisen without it. Moreover, with this method, uniform heat conduction is not achieved, and the shrinkage dimensions of the printed wiring board during heat curing are not uniform. There was also a problem that it was not possible to process at a certain position when applying . Furthermore, in the case of "Daylight", the pressure applied to the wall made of rubber or the like and the printed wiring board during pressing are not equal. For this reason, it was not possible to ensure sufficient airtightness between the wall and the heat platen, resulting in problems such as air bubbles remaining at the edges of the multilayer printed wiring board. The present invention was made in view of the above-mentioned conventional problems, and its purpose is first to prevent any air bubbles from remaining in the completed multilayer printed wiring board, and to create a multilayer printed wiring board with no residual stress. An object of the present invention is to provide a method for efficiently manufacturing printed wiring boards. Another object of the present invention is to provide an apparatus with a simple configuration for use in applying such a manufacturing method. (Means for Solving the Problems) The method adopted by the present invention to solve the above problems will be explained with reference to FIGS. 1 and 2, which correspond to embodiments. When manufacturing a multilayer printed wiring board 20 by laminating a plurality of formed substrates 21 and a plurality of adhesive base materials 22 for bonding them, at least one air intake port 11 that opens upward is formed.
The substrate 21 and the adhesive base material 22 are alternately stacked and placed on the surface plate 10 having at least one exhaust port 12 communicating with the air intake port 11 outside the pressure hot press 60. At the same time, these substrates 21
and covering the entire adhesive base material 22 from above with a heat-resistant and airtight flexible sheet 30,
The entire circumference of the portion of the flexible sheet 30 located on the outer periphery of the substrate 21 etc. is fixed and set airtightly on the surface plate 10 using the fixing frame 40, screw fasteners and elastic material, and then , by inserting the substrate 21 and the like between the pressurizing and hot press machines 60 together with the surface plate 10 while maintaining the set state with screw fasteners, and discharging the gas in the flexible sheet 30 through the exhaust port 12. After reducing the pressure inside the flexible sheet 30, the substrate 21 and the adhesive base material 22 are heated and pressed together with the surface plate 10 and the flexible sheet 30 between a pressurizing hot press machine 60 at a low pressure of 20 kg/cm ² or less. This is a method for manufacturing a multilayer printed wiring board 20. Further, the apparatus according to the present invention applied when carrying out this method has a pressurized heat generating apparatus having at least one intake port 11 opening upwardly and at least one exhaust port 12 communicating with the intake port 11. A surface plate 10 separate from the press machine 60, a substrate 21 placed on this surface plate 10 outside the pressurizing heat press machine 60, and an adhesive base material 22 for bonding these together.
a heat-resistant and airtight flexible sheet 30 for covering the entire surface; and a fixing device that presses the entire circumference of the portion of the flexible sheet 30 located on the outer periphery of the substrate 21 etc. onto the surface plate 10. a frame 40; and a fixed frame 40 formed around the surface plate 10.
When the flexible sheet 30 is fixed on the surface plate 10 by the fixing member 50, the substrate 21 etc. are fixed on the surface plate 10.
By inserting this surface plate 10 between the pressure hot press machines 60 and discharging gas from the exhaust port 12, the substrate 2 can be integrally supported on the substrate 2.
Multilayer printed wiring board manufacturing equipment 1 that enables pressurized hot pressing while keeping the surroundings of the first class airtight
It is 00. (Actions of the Invention) By adopting the above-described measures, the present invention has the following effects. First, in the method according to the present invention, the substrate 21
and adhesive base material 22 are placed on the surface plate 10.
The product is airtightly covered with a flexible sheet 30 fixed to the side, and the product set in this way is inserted between the pressurizing and hot press machines 60 for manufacturing. The hot press operation and the above-mentioned setting operation are completely separated. In this way, compared to the conventional method in which all the work was performed between the pressurizing and hot press machines 60, it is possible to perform the work very efficiently. Further, the adhesive base material 22 and the flexible sheet 30 are placed and covered airtightly with the flexible sheet 30 fixed to the surface plate 10 side, so that the gas in the covered part is removed. Since only the gas is discharged from the exhaust port 12 of the surface plate 10, the amount of gas that must be exhausted is considerably smaller than that of the conventional method. Therefore, in this method, not only the gas between the substrates 21 is reliably discharged, but also the time required for bonding the adhesive base material 22 with the flexible sheet 30 is reduced. In particular, after being airtightly covered with a flexible sheet 30 and evacuated, pressing was performed at a low pressure of 20 kg/cm ² or less and with a pressure hot press machine 60.
The resin in the convex parts of the conductor circuit is pressed at low pressure, so it does not become particularly thin, and since it is pressed with a press, the resin is not confined to the periphery but is pushed out from the center and There are no air bubbles left in the center like in the autoclave method. The printed wiring board manufacturing apparatus 100 used to carry out the method according to the invention described above has the effects of the method described above, and
A flexible sheet 30 and a fixed frame 40 are placed on the surface plate 10.
Since the fixing member 50 and the fixing member 50 can be assembled integrally, the configuration is extremely simple. Furthermore, the gas between the respective substrates 21 can be reliably discharged. (Example) Next, each invention will be described according to a specific printed wiring board manufacturing apparatus 100 shown in the drawings. First, as shown in FIG. 1, the manufacturing method according to the present invention is based on a surface plate 10 having at least one intake port 11 opening upward and at least one exhaust port 12 communicating with the intake port 11. board 21
and the adhesive base material 22 are alternately stacked and placed. Then, the entire substrate 21 and adhesive base material 22 are covered from above with a heat-resistant and airtight flexible sheet 30. Thereafter, the entire circumference of the portion of the flexible sheet 30 located on the outer periphery of the substrate 21 and the like is airtightly fixed onto the surface plate 10. In this embodiment, this fixing is done using a fixing member 50 as described later, but other methods may also be used.
For example, the entire outer periphery of the flexible sheet 30 may be bonded with resin. The gas in the flexible sheet 30 is exhausted through the exhaust port 12 by a vacuum pump (not shown) or the like. As a result, the pressure inside the flexible sheet 30 is reduced, and the gas remaining between each substrate 21 is removed from each substrate 21.
1 into the flexible sheet 30, and then discharged to the outside through the above-mentioned exhaust port 12. After that, the substrate 21 and the adhesive base material 22 are heat-pressed together with the surface plate 10 and the flexible sheet 30 between a pressurizing heat press machine 60 at a low pressure of 20 kg/cm ² or less, thereby producing a desired multilayer print. Wiring board 2
0 is manufactured. A printed wiring board manufacturing apparatus 100 used in applying this manufacturing method has the following configuration. That is, this printed wiring board manufacturing apparatus 100 mainly includes a surface plate 10, a flexible sheet 30, a fixed frame 40, and a fixed member 50. The surface plate 10 has at least one air intake port 11 that opens upward on its upper surface side, and at least one exhaust port 12 that is formed within the surface plate 10 and communicates with the air intake port 11. This surface plate 10 is
It is made of SUS304 or SUS630, and also has the above-mentioned intake port 11 and exhaust port 1.
2 is formed by appropriately dividing plates made of these materials and fixing them to each other. Of course, a vacuum pump (not shown) is connected to the exhaust port 12 of the surface plate 10. A flexible sheet 30 for covering each substrate 21 and adhesive base material 22 placed on this surface plate 10
must have sufficient airtightness to prevent gas from entering inside. Furthermore, since the flexible sheet 30 must contract as the gas inside it is discharged, it must have flexibility as its name suggests. Furthermore, since the flexible sheet 30 is placed in the hot press 60 and heated, it must have sufficient heat resistance. The periphery of the flexible sheet 30 is fixed to the upper surface of the surface plate 10 by a fixing frame 40 made of the same material as the surface plate 10 described above. The fixing frame 40 is specifically fixed to the surface plate 10 by a fixing member 50. For this fixing member 50, a clamp device as shown in FIG. 2 was used. In order to use this clamp device, the flexible sheet 30 and the fixed frame 40 were arranged in the following relationship. That is, the lower inner circumferential surface of the fixed frame 40 and the flexible sheet 30 are joined together, and the sealing member 51 made of an elastic material is interposed between the lower outer circumferential surface of the fixed frame 40 and the flexible sheet 30,
The fixing frame 40 is fixed by pressing the upper surface of the fixing frame 40 toward the surface plate 10 using a clamp device. The fixing frame 40 is fixed to the surface plate 10 by using a plurality of screw fasteners formed around the surface plate 10, and by storing it in an annular groove formed on the surface plate 10 located inside the screw fasteners. a sealing member 5 whose upper end protrudes from the surface of the surface plate 10;
1 constitutes a fixing member 50, and the fixing member 50 may be used to implement the fixing member 50. The sealing member 51 used in each of the above cases must be bent by the pressure applied by the pressure heat press machine 60, and must also have heat resistance, so it is made of flexible silicone. It is made of rubber. Next, each example will be explained by showing specific numerical values etc. when the present invention is implemented. Example 1 An epoxy material with a size of 340 mm x 510 mm and a thickness of 0.2 mm was used as the substrate 21, and the thickness was
Pin lamination was performed via a 0.2 mm adhesive base material 22, and the layers were alternately stacked to form a multilayer printed wiring board 20 with a total of 8 layers and a board thickness of 1.6 mm. A total of six sets of such laminates were combined and fixed on both sides with stainless steel plates, and then placed on a surface plate 10.
Then, a sealing member 51 made of an O-ring with a diameter of 1 mm was fitted into the annular groove 13 of the surface plate 10, and a flexible sheet 30 made of a silicone rubber sheet with a thickness of 1 mm was covered over the substrate 21 and the like. After that,
The screw fastener is fixed to the surface plate 10 by operating the thumbscrew, and the fixing frame 40 is pressed against the surface plate 10 side to seal the inside of the flexible sheet 30. After setting in this way, the manufacturing apparatus 100 for the pilint wiring board is inserted into the pressure heat press machine 60, and the air in the flexible sheet 30 is evacuated from the exhaust port 12 of the surface plate 10 by a vacuum pump. However, it turned out to be -752mmHg. Next, this printed wiring board manufacturing apparatus 100
of. Pressure is applied at a low pressure of 14Kg/ ^cm2 using a pressure heat press machine 60, and the temperature is raised at a rate of 5℃/min to 170℃, and the maximum temperature is 170℃.
The temperature was maintained at ℃ for 60 minutes and the mixture was heated and pressurized. Thereafter, it was cooled to room temperature at a rate of 5° C./min. When pressed using the conventional method described above and the improved method according to the present invention under the same thermal history, the results shown in Table 1 were obtained. According to the present invention, as described above, not only do air bubbles that can cause fatal defects in the multilayer printed wiring board 20 not remain between the layers, but also variations in board thickness and dimensional changes due to heating and pressurization are small. , good results were obtained. Example 2 Glass bismaleide triazine with a size of 340 mm x 340 mm and a thickness of 0.3 mm was used as the substrate 21, and 213 of these substrates were laminated with pins via an adhesive base material 22 with a thickness of 0.2 mm, resulting in a total of 6 layers. The layers were alternately laminated to form a multilayer printed wiring board 20 with a thickness of 1.6 mm. A total of four sets of such laminates were combined and fixed on both sides with stainless steel plates, and then placed on a surface plate 10. Then, a sealing member 51 made of an O-ring with a diameter of 0.8 mm was fitted into the annular groove 13 of the surface plate 10, and a flexible sheet 30 made of a silicone rubber sheet with a thickness of 1 mm was covered over the substrate 21 etc. . After that, the clamp 5 shown in FIG.
3, the screw fasteners are fixed to the surface plate 10, and the fixing frame 40 is crimped to the surface plate 10 side, thereby sealing the interior of the flexible sheet 30.

【table】

【table】

[Table] After setting in this way, the printed wiring board manufacturing apparatus 100 is inserted into the pressurizing heat press machine 60, and the inside of the flexible sheet 30 is moved by a vacuum pump from the exhaust port 12 of the surface plate 10. When the air was removed,
It became less than 10Torr. Next, the clamp 53 is removed while maintaining this reduced pressure state, and the printed wiring board manufacturing apparatus 10 is turned off.
0 is pressurized at a low pressure of 8 kg/cm ² with a pressure heat press machine 60 (in this case a hot press), the temperature is raised to 140°C at a rate of 5°C/min, this state of 140°C is maintained for 5 minutes, and then further The temperature was raised to 175°C at a rate of 5°C/min. This 175°C state was maintained for 80 minutes to heat and pressurize. Thereafter, it was cooled to room temperature at a rate of 5° C./min. When pressed using the conventional method described above and the improved method according to the present invention under the same thermal history, the results shown in Table 2 were obtained. According to the present invention, as in Embodiment 1, not only do air bubbles that can cause fatal defects in the multilayer printed wiring board 20 not remain between the layers, but also variations in board thickness and dimensional changes due to heating and pressurization are prevented. Good results were obtained with little variation. That is, even when glass bismaleide triazine, which has a low clay content when melted, was used, it was possible to obtain a desired product. (Effects of the Invention) As described in detail above, in the present invention, as exemplified in each of the above embodiments, the flexible sheet 30 is directly covered on the surface plate 10 and stored inside the flexible sheet 30. The substrate 21, etc. to be processed is pressed at 20 kg/
The method and equipment are characterized by their construction, which heats and presses them at low pressures of less than cm ^2. This firstly prevents any air bubbles from remaining in the completed multilayer printed wiring board, and also reduces residual stress. Therefore, it is possible to efficiently manufacture a multilayer printed wiring board that does not require a single layer. Moreover, according to the printed wiring board manufacturing apparatus 100 according to the present invention, it is possible to provide an apparatus with a simple configuration that is used when applying the above manufacturing method.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a printed wiring board manufacturing apparatus according to the present invention, FIG. 2 is a sectional view corresponding to FIG. 1 showing another embodiment, and FIGS. 3 and 4 are sectional views of a conventional method. It is a longitudinal cross-sectional view for explanation. Explanation of symbols, 100...Printed wiring board manufacturing equipment, 10...Surface plate, 11...Intake port, 12...
Exhaust port, 13... Annular groove, 20... Multilayer printed wiring board, 21... Substrate, 22... Adhesive base material,
30...Flexible sheet, 40...Fixed frame, 50...
...Fixing member, 51... Sealing member, 60... Pressure heat press machine.

Claims (1)

[Claims] 1. At least one air intake port opening upward when manufacturing a multilayer printed wiring board by laminating a plurality of substrates on which conductor circuits, etc. are formed, and an adhesive base material for bonding these substrates. The substrates and the adhesive base material are alternately stacked and placed on a surface plate having at least one exhaust port that communicates with the air intake port outside the pressure hot press machine. The entire adhesive base material is covered from above with a heat-resistant and airtight flexible sheet, and the entire circumference of the portion of the flexible sheet located on the outer periphery of the substrate etc. is covered with a fixing frame, The board, etc. is airtightly fixed and set on the surface plate using a screw fastener and an elastic material, and then the board, etc. is heated together with the surface plate while maintaining its set state with the screw fastener. After inserting the flexible sheet between the press machines and exhausting the gas in the flexible sheet through the exhaust port to reduce the pressure inside the flexible sheet, the substrate and the adhesive base material are placed between the surface plate and the flexible sheet. between the pressure heat press machine along with the adhesive sheet.
A method for producing a multilayer printed wiring board using heat pressing under low pressure of 20Kg/cm ² or less. 2. A clamp device provided on the surface plate is employed as a means for performing the fixing, and the inner circumferential lower surface of the fixed frame and the flexible sheet are joined to each other, and the outer circumferential lower surface of the fixed frame and the flexible sheet are joined together. A sealing member made of an elastic material is interposed between the flexible sheets, and the fixed frame is fixed by pressing the upper surface of the fixed frame toward the surface plate by the clamping device. 1. The manufacturing method described in Hole 1. 3 at least one intake port opening upward;
A surface plate separate from the pressurizing heat press machine and having at least one exhaust port communicating with the inlet port, and a substrate placed on the surface plate outside the pressurizing heat press machine and bonded thereto. A heat-resistant and airtight flexible sheet for covering the entire adhesive base material, and pressing the entire circumference of the portion of the flexible sheet located on the outer periphery of the substrate etc. onto the surface plate. and a fixing member formed around the surface plate to fix the fixed frame, and when the flexible sheet is fixed on the surface plate by the fixing member, the substrate, etc. can be integrally supported on the surface plate, and by inserting this surface plate between pressurizing and hot press machines and discharging gas from the exhaust port, the surroundings of the substrate etc. can be kept in an airtight state. A manufacturing device for multilayer printed wiring boards that enables pressurized heat pressing while holding the board. 4. A clamp device provided on the surface plate is employed as the fixing member, and the inner circumferential lower surface of the fixed frame and the flexible sheet are joined to each other, and the outer circumferential lower surface of the fixed frame and the flexible sheet are joined together. Claim 3, wherein a sealing member made of an elastic material is interposed in between, and the fixing frame is fixed by pressing the upper surface of the fixing frame toward the surface plate by the clamp device. The manufacturing equipment described. 5. The manufacturing apparatus according to claim 3 or 4, wherein the sealing member is made of silicone rubber.