JP2005340511A - Method for manufacturing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a printed wiring board for transferring heat between layers without generating the non-uniformity of thermal distribution in a cure process. <P>SOLUTION: In a method for manufacturing a printed wiring board having a process to pressurize and heat a printed wiring board 24 on which a plurality of layers are laminated by interposing it by metallic plates 23, the printed wiring board 24 is pressurized and heated in a status that the metallic plates 23 are connected so that heat can be transferred by heat transmitting materials 31. Thus, each metallic board 23 is quickly heated so that the non-uniformity of thermal distribution can be canceled, and that the time of the cure process can be also shortened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a printed wiring board that is an internal component of an electronic device, and more particularly to an improvement in a process of pressurizing and heating a printed wiring board between metal plates.

  In the manufacturing process of printed wiring boards, insulating materials, multilayer materials, or electronic components are printed using adhesives to insulate circuit parts of printed wiring boards, to make multilayers, or to attach flat electronic components. A process of bonding to a plate and curing under high temperature and high pressure is performed. Such a process is called a curing process.

  For example, when an insulating material is bonded, a printed wiring board member 13 having a circuit wiring layer 12 formed on an insulating base material 11 as shown in cross-sectional views before and after the curing process in FIGS. Then, the insulating material 14 provided with the thermosetting adhesive layer 15 is heated under pressure with the thermosetting adhesive layer 15 of the insulating material 14 facing the circuit wiring layer 12 of the printed wiring board member 13. Thus, a printed wiring board in which the insulating material 14 is bonded to the printed wiring board member 13 so that the thermosetting adhesive layer 15 is embedded in the circuit wiring layer 12 is obtained.

  Also, a curing process is performed when a multilayer material in which a plurality of printed wiring boards on which a circuit is formed is laminated is laminated with an interlayer adhesive layer provided between the printed wiring boards to form a multilayer wiring board. .

  Such a curing process for a printed wiring board is conventionally performed using a press apparatus having a pair of upper and lower press metal plates (heat discs) heated by a heat source. In the curing process using this press machine, a metal plate with a thickness of several millimeters is interposed between the printed wiring boards to be pressed and heated (hot press) in order to ensure the smoothness of the press surface and improve heat conduction. The printed wiring board is heated and pressurized by heat transfer from the metal plate. In addition, when pressure heating is performed with the printed wiring board sandwiched only between metal plates, there is a problem in the embedding property of the adhesive between the circuits and the uniformity of the pressure. Between the wiring board and the metal plate, paper or a film generally called a cushioning material is sandwiched, and the printed wiring board is pressurized and heated through the cushioning material.

  Also, in order to improve productivity during the curing process, multiple printed wiring boards and multiple metal plates can be stacked in multiple layers to increase the number of printed wiring boards processed in a single curing process. Has been done. That is, FIG. 2 schematically shows a metal plate, a printed wiring board, and the like provided between a pair of upper and lower heating plates at the time of the curing process, and between the lower heating platen 21 and the upper heating platen 22. A plurality of metal plates 23 are provided, and a plurality of printed wiring boards 24 to be pressurized and heated are provided between the metal plates 23 via cushion materials 25, respectively. When the combination of one printed wiring board 24 and the upper and lower cushion members 25 and the upper and lower metal plates 23 sandwiching the printed wiring board is counted as one layer, in the example shown in FIG. A curing process is performed.

  The number of printed wiring boards that are subjected to a curing process at a time is better from the viewpoint of productivity improvement, but there are limitations due to the curing temperature of the adhesive and the degree of variation in the temperature history of each printed wiring board. The appropriate number is determined according to the conditions. Also, the curing time is determined in the same manner. Then, after the printed wiring board, metal plate, and cushion material are incorporated into the press device so that the determined number of layers is obtained, the press pressure and heating temperature are adjusted according to the determined program, and the curing process is performed for a predetermined time. .

  Known techniques related to the curing process include, for example, Patent Document 1 and Patent Document 2. That is, Patent Document 1 discloses a hot plate that can be uniformly heated by a small output electric heater with respect to a hot plate for a hot press apparatus used in a curing process. Further, Patent Document 2 discloses an apparatus in which a far-infrared heater is provided to eliminate heating unevenness with respect to a hot plate for a hot press apparatus and a net press apparatus using the same.

As disclosed in Patent Document 1 and Patent Document 2, conventionally known techniques mainly aim to speed up heat transfer during hot pressing and to reduce variations in heat distribution between layers. There are many. In addition to the goal of increasing the productivity of hot presses, if the temperature distribution and temperature history vary between layers where cushioning materials, printed wiring boards, etc. are laminated, the defective rate of printed wiring boards after curing treatment This is to reduce the quality difference between products.
Japanese Utility Model Publication No. Hei 6-42133 JP-A-7-80871

  As described above, in the publicly known technology, with respect to the press device used in the curing process, mainly the improvement of the heating source such as the improvement of the efficiency of the electric heater and the improvement of the heating method by thermal radiation such as far infrared rays has been made. However, the improvement was not always effective. The reason for this is that in an actual curing process, heat conduction from a heating source such as a hot plate to a printed wiring board is much more conductive than a hot plate or metal plate, which is a cushion material made of paper or film. This is because it is performed through a low material. In other words, when a plurality of layers are laminated and heated under pressure in order to cure a plurality of printed wiring boards at once, the heat transfer from the hot plate is not uniform between the layers due to the interposition of the cushion material. The temperature history varies between layers. In addition, the temperature rise and cooling time also becomes long. In particular, when the curing device is a vacuum system, heat transfer due to air conduction is lost, so that there is a high possibility of variations in temperature history between layers. Therefore, there has been a demand for a curing method that can efficiently transfer heat from a hot platen between layers without unevenness of heat distribution.

  The present invention advantageously responds to the above-described demand, and an object of the present invention is to provide a method for manufacturing a printed wiring board that can be transmitted between layers without unevenness of heat distribution in a curing process.

The present invention provides a method for producing a printed wiring board having a step of pressurizing and heating a printed wiring board in which a plurality of layers are laminated with a metal plate,
A method for manufacturing a printed wiring board, wherein the metal plates are pressurized and heated in a state where the metal plates are connected to each other by a heat conductive material so as to be capable of transferring heat.

  According to the method for manufacturing a printed wiring board of the present invention, since the curing process is performed in a state in which the metal plates for pressurizing and heating the printed wiring boards are connected to each other by a heat conductive material, the laminated printed board is used. Heat conduction to the wiring board is performed more rapidly than before. Therefore, the variation in the heat distribution between the layers is reduced, and the difference in thermal history in the printed wiring board for performing the curing process is reduced, so that the product quality can be made uniform and good quality can be stably obtained. be able to. In addition, the heating time during curing can be greatly shortened, and productivity is improved.

  FIG. 3 is a cross-sectional view showing an example in which a plurality of printed wiring boards are stacked in a press apparatus in order to perform a curing process according to the present invention. In the figure, a plurality of metal plates 23A, 23B, 23C, 23D and a plurality of metal plates 23 sandwiched between the lower heat platen 21 and the upper heat plate 22 provided in the press device. A printed wiring board 24 and a plurality of cushion members 25 interposed between the printed wiring board 24 and the metal plate 23 are provided. And the heat-transfer member 31 which consists of a heat conductive material is provided in connection with the side end surface of each metal plate 23A, 23B, 23C, 23D.

  As shown in FIG. 3, each metal plate 23 </ b> A, 23 </ b> B, 23 </ b> C, 23 </ b> D is connected to the heat transfer member 31, and these metal plates are pressurized and heated in a state where heat can be transferred through the heat transfer member 31. Thus, during the curing process, each printed wiring board passes through the heat transfer member 31 connected to the metal plates 23A and 23D from the metal plates 23A and 23D in contact with the upper and lower heating plates 21 and 22. Heat is transferred to the metal plates 23B and 23C sandwiching 24 to heat each metal plate. Therefore, as a result of the heat from the hot plates 21 and 22 being quickly transmitted to the metal plates 23A, 23B, 23C, and 23D, not only the printed wiring board arranged near the hot plate but also the middle of the upper and lower hot plates. Even if the printed wiring board is subjected to heating, the difference in heating history for each printed wiring board to be processed becomes small, and the quality of the product becomes uniform and good.

  Further, since each printed wiring board 24 is heated quickly, the temperature raising time during the curing process can be greatly shortened, and as a result, the productivity during the curing process is improved.

  Further, since the heat transfer member 31 is provided between the lower heat plate 21 and the upper heat plate 22, the heat transfer member 31 plays a role of reducing the outflow of heat to the outside at the time of temperature increase and temperature maintenance. When the temperature of the printed wiring board is lowered after the processing is completed, the heat transfer member 31 serves as a heat sink to accelerate the cooling of the printed wiring board. Therefore, productivity during the curing process is improved.

  Furthermore, since heat is quickly transferred to each printed wiring board, variation in the thermal history between printed wiring boards is reduced. It becomes possible to increase. In this respect also, the productivity during the curing process is improved.

  The material of the heat transfer member 31 is advantageously a material having a high thermal conductivity from the viewpoint of the function of transferring heat to each metal plate. For example, copper has a high thermal conductivity of 403 W / m · K when the thermal conductivity is 0 ° C. and 395 W / m · K when the thermal conductivity is 100 ° C., and thus is suitable for use in the heat transfer member 3. In addition to copper, metal materials such as aluminum and stainless steel also have a much higher thermal conductivity than the cushion material (paper, film, etc.) 25, so that they can be used as the heat transfer member 31 of the present invention. it can.

  The thickness of the heat transfer member 31 is not particularly limited. Although it varies depending on the material of the heat transfer member 31, for example, when the heat transfer member 31 is copper, a thickness of about several millimeters is sufficient from the viewpoint of thermal conductivity between the metal plates.

  If the connection between the heat transfer member 31 and each side end face of each of the metal plates 23A, 23B, 23C, 23D is simply in contact, the heat transfer member 31 is also transferred from each metal plate 23 to the heat transfer member 31. Therefore, the desired effect of the present invention can be obtained. Moreover, you may make it connect a heat-transfer member and each metal plate with a well-known connection means.

  Further, as shown in FIG. 3, the heat transfer member 31 extends in the horizontal direction in contact with the upper surface or the lower surface of the metal plate in addition to the vertical portion 31a extending in the vertical direction between the upper and lower heating plates 21 and 22. It may have a horizontal portion 31b. Thus, the heat transfer member 31 having the horizontal portion 31b is in contact with not only the end surface of the metal plate 23 but also the upper surface or the lower surface of the metal plate 23, so that the contact area with the metal plate 23 is increased and the efficiency is further increased. It can conduct heat well. The horizontal portion 31b is integrally formed with the vertical portion 31a, for example, by the same material as the vertical portion 31a and having a thickness of about several millimeters and extending from the side edge of the metal plate to an appropriate length toward the center. can do. Further, the horizontal portion 31b may be provided as a member different from the vertical portion 31a and connected to the vertical portion 31a.

  Further, the vertical portion 31 a of the heat transfer member 31 may be formed by connecting a plurality of members between the lower heat platen 21 and the upper heat platen 22. For example, each member constituting the vertical portion 31a has a length substantially equal to the distance between adjacent metal plates in the vertical direction, and the vertical portion 31a is formed by connecting such members in the vertical direction. It may be.

  Since it is shown in a sectional view in FIG. 3, it does not appear in the drawing, but it is also possible to provide the heat transfer member 31 so as to cover the four sides between the lower heating platen 21 and the upper heating platen 22. In this case, heat conduction is performed more quickly.

  As shown in FIG. 3, a plurality of printed wiring boards were stacked in a press apparatus and cured. At this time, first, the copper heat transfer member 31 (thickness 2 mm) was provided so that the horizontal portion 31b of the heat transfer member 31 was positioned on the metal plate 23A positioned at the lowermost part.

  Next, an arbitrarily defined cushion material 25 was laid, and then a printed wiring board 24 to be cured was placed on the cushion material 25. Next, after the cushion material 25 is laid on the printed wiring board 24, the heat transfer member 31 is arranged so that the horizontal portion 31 b of the heat transfer member 31 is provided on the cushion material 25. The metal plate 23B was placed on the horizontal portion 31b of the 31.

  Similar stacking was performed on a plurality of printed wiring boards to be processed, and the stacked structure shown in FIG. 3 was obtained. Then, a curing process was performed by a hot press device under predetermined pressure and temperature conditions. In this curing process, the heat transfer member 31 is connected to all the metal plates 23A, 23B, 23C, and 23D, and thus heat conduction was fast. Therefore, the heating time and the cooling time are shortened. As a result, the time required for the curing process is shortened to 0.7 when the time required for the conventional method in which the heat transfer member 31 is not provided is 1. .

  When the printed wiring board was examined after the curing process, the dispersion of the heat distribution between the layers was reduced during the curing process, so that the quality was uniform in each printed wiring board and good results were obtained.

It is sectional drawing which shows typically the place which bonded together the wiring board member and insulating material of a printed wiring board by the curing process. It is sectional drawing which shows typically the metal plate, printed wiring board, etc. which are provided between a pair of upper and lower heating boards at the time of a curing process. It is sectional drawing which shows an example which laminated | stacked the some printed wiring board within the press apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Insulation base material 12 Circuit wiring layer 13 Printed wiring board member 14 Insulating material 15 Thermosetting adhesive layer 21 Hot plate 22 Hot plate 23 Metal plate 24 Printed wiring board 25 Cushion material 31 Heat transfer member

Claims (1)

In the method for producing a printed wiring board having a step of pressurizing and heating a printed wiring board in which a plurality of layers are laminated with a metal plate,
A method of manufacturing a printed wiring board, wherein the metal plates are heated under pressure in a state where the metal plates are connected to each other by a heat conductive material so as to be capable of transferring heat.

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