JP2006156908A - Method for manufacturing printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain sufficient welding between resin-made sheets each other particularly at a flexible part in a method for manufacturing a printed circuit board having a rigid part and the flexible part, by welding a plurality of the resin-made sheets having a conductor pattern with hot pressing after laminating them. <P>SOLUTION: The resin-made sheet 1 with an opening 1a formed to a position corresponding to the flexible part, and the resin-made sheet 2 without an opening, are prepared and placed on a hot pressing plate 12. The laminated resin-made sheets 1, 2 are clamped and heated with the hot pressing plates 11, 12 having protruding parts 11b, 12b with the same size as that of the opening 1a. On that occasion, each of the protrusions 11b, 12b of the hot pressing plates 11, 12 is advanced so as to fit into the opening 1a of the resin-made sheet. Accordingly, shock absorbing materials 17, 18 made of a flexible material are pushed into the opening 1a by pressure and enter the inside of the opening 1a without a gap. Heat and pressure applied by the hot pressing plates 11, 12 can be excellently transmitted to the resin-made sheets 1, 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a printed circuit board, and more particularly to a method for manufacturing a sheet-like printed circuit board having a bendable portion in the middle thereof.

  2. Description of the Related Art A sheet-like printed circuit board is known that is manufactured by laminating a plurality of resin sheets on which conductor patterns are printed and sandwiching them with a hot press plate from above and below to weld them together. The sheet-like printed circuit board manufactured in this way is easy to mount electronic circuits at high density, and has high application characteristics for use in electronic devices that are remarkably miniaturized, such as cellular phones.

  Also, if the number of laminated sheets of resin is partially reduced, the portion with a small number of laminated sheets becomes more flexible than the portion with a large number of sheets, so that portion becomes a pseudo hinge, such as a mobile phone. It can be attached to the movable part of the, and the use is further expanded. A printed board including such a plate-like portion (rigid portion) on which electronic circuits are densely mounted and a bendable portion (flexible portion) that connects the plate-like portions in a hinge-like manner is referred to as a rigid-flexible substrate. It is called.

  Then, as a method of manufacturing a rigid-flexible substrate in a simple process, a resin film in which openings are formed on a resin film to be laminated is formed in a resin film in which openings are formed differently for each film. A method of sandwiching and welding between the two has been developed (for example, Patent Document 1).

As another method, a method has been developed in which a release sheet is inserted into a region to be formed in a flexible portion, a slit is formed, and a portion surrounded by the slit is removed after welding to form a flexible portion. (For example, Patent Document 2).
JP 2002-305382 A JP 2003-264369 A

  In the manufacturing method disclosed in Patent Document 1, the number of resin films to be laminated differs depending on the difference in planar position (for example, one in the region where the flexible portion is formed, but one rigid portion is 3 layers are stacked in the region to be formed, and 4 layers are stacked in the region where the other rigid portion is formed). That is, the thickness of the resin film differs from part to part. Therefore, when the laminated resin film is sandwiched from above and below by a press machine and heated, substantially uniform and sufficient pressure is applied over the entire surface of the resin film so that the heat from the press machine is evenly and sufficiently transmitted to the resin film. In order to achieve this, heat pressing is performed by interposing an elastic cushioning material between the press machine and the resin film.

  However, when the difference in the thickness of the resin film is large, even if a highly flexible material is selected as the cushioning material, the pressure and heat from the press machine are applied to the thin part (opening) of the resin film. Therefore, there is a problem that the resin films of the flexible part are not particularly well welded.

  This will be further described with reference to FIG. 5 (a) and 5 (b) show an apparatus to which a conventional manufacturing method is applied. A resin film 41 in which no opening is formed on a lower heating press plate 40, and a resin film 42 in which an opening 42a is formed. Are placed two by two, and a cushioning material 43 having flexibility is interposed on the resin film 42 having openings formed thereon, and pressure is applied downward by the upper heating press plate 44. FIG. 5A shows a state before pressing, and FIG. 5B shows a state during pressing. In order to make the configuration easy to understand, the thicknesses of the resin films 41 and 42 and the buffer material 43 are exaggerated.

  In this apparatus, when the upper heating press plate 44 is gradually moved downward and pressure is applied, the cushioning material 43 enters the opening 42a of the resin film 42 while being deformed, but when the dent width of the opening portion is large. The lower surface of the cushioning material 43 entering the opening 42a does not reach the upper surface 41a of the resin film 41 (FIG. 5B), and therefore the resin film 41 in the portion corresponding to the opening 42a (flexible portion) in particular. There was a problem that the welding of the film was only incomplete. When the opening width of the opening 42a is small, the lower surface of the cushioning material 43 entering the opening 42a will come into contact with the resin film surface 41a. Even in this case, the lower resin applied via the cushioning material 43 The pressure on the surface of the film 41 is considerably small, and welding between the resin films 41 in the flexible part cannot be sufficiently obtained. Although it is conceivable to select the cushioning material 43 with extremely high flexibility, the cost is increased, and the pressure transmission to the surface of the resin film 41 in the flexible portion is not improved so much.

  The present invention was devised in view of the above circumstances, and a printed circuit board having a rigid portion and a flexible portion is manufactured by laminating a plurality of resin sheets having a conductor pattern and welding them by hot pressing. In the method, the resin sheet of the part that forms the flexible part is sufficiently pressed and heated by the hot press plate to obtain sufficient welding between the resin sheets, and the strength is high (the flexible part is damaged) It is an object of the present invention to provide a production method capable of obtaining a rigid-flexible substrate.

  The invention of claim 1 for achieving the above object is a method of manufacturing a printed circuit board having a rigid portion and a flexible portion by laminating a plurality of resin sheets having a conductor pattern and welding them by hot pressing. The step of preparing a resin sheet having an opening formed at a position corresponding to the flexible portion and the resin sheet having the same size as the resin sheet having the opening prepared in the above step and not forming the opening A step of preparing a sheet, and a step of laminating a plurality of the prepared resin sheets, heating them by sandwiching them with a hot press plate from above and below, and welding the resin sheets to each other, When a protrusion having the same size as the opening is formed and the resin sheet is sandwiched, the protrusion fits into the opening and contacts the sheet surface of the resin sheet that does not form the opening. Touching And it features.

  According to a second aspect of the present invention, in the first aspect of the present invention, the protrusion of the hot press plate is obtained by fixing a heat resistant member separate from the hot press plate to the surface of the hot press plate. Features.

  A third aspect of the present invention is the process according to the first or second aspect, wherein a plurality of the resin sheets are stacked and heated by sandwiching the resin sheets from above and below with a hot press plate to weld the resin sheets together. The sheet-like cushioning material is interposed between the resin sheet and the hot press plate.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the resin sheet has positioning holes formed in at least two locations, and the hot press plate has positioning pins. When the resin sheet is sandwiched between the hot press plates, the positioning pins enter the positioning holes to align the resin sheet and the hot press plate.

  According to the first to third aspects of the invention, when the resin sheet laminated with the hot press plate is sandwiched, the protrusion of the hot press plate fits into the opening of the resin sheet and enters. The resin sheet portion forming the flexible portion is applied with sufficient heat and pressure by the protrusions, and a sufficient welded state between the resin sheets is obtained. Therefore, a rigid-flex board having particularly high strength at the flex part can be easily obtained.

  According to the invention of claim 4, when the resin sheet is sandwiched between the hot press plates, the positioning pins enter the positioning holes and the resin sheet and the hot press plate are aligned. The projection of the plate is more smoothly fitted into the opening of the resin sheet. Therefore, a rigid-flex board having particularly high strength at the flex part can be obtained more easily.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, a resin sheet 1 in which an opening 1a is formed in a portion that will later become a flexible part and a resin sheet 2 in which no opening is formed are prepared. Fig.1 (a) shows the plane of the resin sheet 1 which formed the opening part 1a, and FIG.1 (b) shows the plane of the resin sheet 2 which does not form an opening part. In the present embodiment, three sets of rectangular openings 1a and conductor patterns 3 on both sides thereof are formed so that three rigid-flexible substrates 50 (FIG. 4) as products can be taken from one resin sheet. It is formed on the assembled resin sheet 1. The conductor pattern 3 is pasted on the resin sheet 1 by a known method, and the resin sheet on the back side of the conductor pattern 3 is formed with via holes for conducting the conductor pattern 3 of each layer. (Not shown). For convenience, a region 4 indicated by a square section in FIG. 1A indicates a region where the conductor pattern 3 is arranged. In addition, positioning round holes 5 and positioning long holes 6 through which positioning pins described later are inserted are formed at two opposite corners of the resin sheet 1.

  Similarly to the resin sheet 1 having the openings, the resin sheet 2 having no openings is also provided with three identical conductor patterns 7 so that three rigid-flex boards as products can be taken from one resin sheet. It is formed on an assembled resin sheet. Similarly to FIG. 1A, the region 8 shown by the square section in FIG. 1B shows the region where the conductor pattern 7 is arranged, and the resin sheet on the back side of the conductor pattern 7 has via holes. (Not shown) is formed. In addition, positioning round holes 9 and positioning long holes 10 through which positioning pins to be described later are inserted are formed at two opposing corners of the resin sheet.

  Next, hot press plates 11 and 12 for applying pressure by sandwiching the resin sheets 1 and 2 prepared as described above from above and below will be described with reference to FIGS. The hot press plate is composed of an upper hot press plate 11 and a lower hot press plate 12, and is a protrusion having approximately the same size as the opening 1a at a position corresponding to the opening 1a of the resin sheets 1 and 2 laminated together. 11b, 12b. Positioning pins 13 and 14 are erected at the two opposite corners of the lower heat press plate 12, and the positioning pins enter the two opposite corners of the upper heat press plate 11. Holes 15 and 16 are formed.

  The upper and lower hot press plates 11 and 12 constitute protrusions 11b and 12b on one metal (iron, stainless steel, copper, etc.) flat plates 11a and 12a, respectively, using an adhesive member such as polyimide tape. A metal (iron, stainless steel, copper, etc.) plate, a fluororesin (Teflon (registered trademark) plate) plate material, or a polyimide plate material is bonded. In any case, even if the temperature rises to the temperature at which the resin sheets 1 and 2 are welded, the material does not adhere to the resin sheets 1 and 2, the protrusions 11 b and 12 b expand significantly, or cause no change in state. Therefore, the protrusions 11b and 12b adhere to buffer materials 17 and 18 and the opening 1a, which will be described later, during the actual pressing, or the protrusions 11b and 12b can be smoothly detached from the opening 1a after pressing. Troubles such as not being performed will not occur. Moreover, since only the plate members 11b and 12b constituting the protrusions are bonded to the flat plates 11a and 12a, a hot press plate having the protrusions is manufactured by grinding a flat substrate made of metal such as iron. Compared with the case where it does, manufacture is very easy and can reduce the whole manufacturing cost by that much.

  Next, the process of applying pressure and heating the resin sheets 1 and 2 laminated using the hot press plates 11 and 12 will be described. As shown in FIG. 3A, first, a sheet-like cushioning material 17 is placed on the lower heat press plate 12, and one resin sheet 1 having an opening 1a formed thereon is formed with an opening. Two resin sheets 2 that are not used and two resin sheets 1 that are formed with openings 1a are placed in that order. Further, the sheet-like cushioning material 18 is placed thereon. At this time, the round holes 5 and 9 and the long holes 6 and 10 formed in the resin sheets 1 and 2 are inserted into the positioning pins 13 and 14 erected from the lower heat press plate 12, and the resin sheets 1 and 2 are inserted. Since they are laminated, the relative positions of the lower heat press plate 12 and the resin sheets 1 and 2 are appropriate. That is, since the planar positions of the protrusion 12b of the lower heat press plate 12 and the opening 1a of the resin sheet 1 coincide, the protrusion 12b of the lower heat press plate 12 accurately opens the resin sheet during subsequent pressing. It will come to the part 1a. Moreover, in this embodiment, the fluororesin sheet | seat is used as the buffer materials 17 and 18, and the thickness of the buffer materials 17 and 18 is set to the thickness according to the dent width of the opening part 1a which each buffer material contact | abuts, respectively. ing. That is, the thickness t17 of the cushioning material 17 is set to be slightly larger than the recess width of the lower opening 1a, and the thickness t18 of the cushioning material 18 is slightly larger than the recess width of the upper opening 1a. It is set. Further, holes 19 and 20 through which the positioning pins 15 and 16 are inserted are formed in the respective cushioning materials 17 and 18.

  Next, the upper heat press plate 11 is placed on the resin sheets 1 and 2 and the cushioning materials 17 and 18 laminated on the lower heat press plate 12 as described above, and the through holes 15 and 16 have the positioning pins 13 and 16. 14 to be inserted. Since the resin sheets 1 and 2 are inserted into the positioning pins 13 and 14 and positioned at appropriate positions, the planar positions of the protrusion 11b of the upper hot press plate 11 and the upper opening 1a are also matched.

  Next, as shown in FIG. 3 (b), the press head 21 above the upper hot press plate 11 is gradually moved downward, and the cushioning materials 17, 18 are moved between the lower press base 22. Pressure is applied to the resin sheets 1 and 2 from above and below. At this time, a heater (not shown) provided in the press head 21 and the press base 22 is energized, and the press head 21 and the press base 22 themselves are heated to high temperatures, so that the upper and lower hot press plates 11 and 12 are heated. It is heated and heated to a temperature before the resin sheets 1 and 2 are melted. And since high pressure is applied to the resin sheets 1 and 2 with this heating, the resin sheets 1 and 2 are welded together. Each of the resin sheets 1 and 2 is processed so as to be more easily welded by irradiating the surface with ultraviolet rays and changing the polymer structure on the surface to a monomer structure before being laminated. It is preferable to keep it. In the present embodiment, the heaters built in the press head 21 and the press base 22 are energized, and the press head 21 and the press base 22 themselves become high temperature. A heater may be housed inside, and the hot press plates 11 and 12 themselves may be at a high temperature, or the whole may be inserted into a heating chamber and heated from the surroundings.

  And in said thermocompression-bonding process, since the protrusions 11b and 12b of the upper and lower hot press plates 11 and 12 try to enter so as to fit into the opening 1a of the resin sheet, respectively, they are made of a flexible material. The buffer materials 17 and 18 are pushed into the opening 1a by pressure, and enter the opening 1a without any gap (FIG. 3B). Therefore, the heat and pressure applied by the hot press plates 11 and 12 are efficiently transmitted to the resin sheets 1 and 2, and in particular, the welding of the resin sheets 2 forming the flexible part is formed well.

  After the resin sheets 1 and 2 are welded together, the upper hot press plate 11 is moved upward to release the pressure, and the welded resin sheets 1 and 2 are extracted from the positioning pins 13 and 14 and taken out. At this time, since the protrusions 11b and 12b of the hot press plates 11 and 12 are made of the material having the above-described conditions, they are attached to the buffer materials 17 and 18 or greatly expanded so that it is difficult to pull out from the opening 1a. Trouble that becomes or does not occur. The resin sheets 1 and 2 extracted from the hot press plate 12 are then cut along the outer circumferential line L (FIG. 1) of the conductor patterns 3 and 7 and the opening 1a to be separated from the resin sheets 1 and 2, It becomes three rigid-flexible substrates. FIG. 4 shows the rigid-flex board 50 after being separated from the resin sheet. A portion formed only by the two-layer resin sheet 2 by being cut along the outer peripheral line L constitutes a flexible portion (flexible portion) 50f, and is composed of the remaining five layers of resin sheets 1 and 2. The portion becomes the rigid portion 50r.

  As described above, the rigid-flexible substrate 50 having particularly high strength of the flexible portion 50f can be easily manufactured. In the above embodiment, the completed rigid-flex board 50 has one flexible part 50f. However, it is also possible to manufacture a rigid-flexible board having a plurality of flexible parts with a plurality of openings 1a of the resin sheet 1. is there. Moreover, in the said embodiment, the buffer materials 17 and 18 are inserted between the resin-made sheets 1 and 2 laminated | stacked with the hot press plates 11 and 12, and the heat and pressure of the hot press plates 11 and 12 are the buffer materials 17 and 18. However, the upper and lower hot press plates 11 and 12 are in direct contact with the resin sheets 1 and 2 without inserting the cushioning materials 17 and 18. Also good. In this case, it is necessary to match the size and shape of the protrusions 11b and 12b of the hot press plates 11 and 12 more precisely with the size and shape of the opening 1a. Cost is not required, and the efficiency of transferring the heat and pressure applied by the hot press plates 11 and 12 to the resin sheets 1 and 2 is increased, so that the time required until the resin sheets are welded can be shortened. Moreover, if the protrusions 11b and 12b are formed of the same material as described above, it is possible to prevent the protrusions 11b and 12b from adhering to the resin sheets 1 and 2 and being difficult to be extracted from the opening 1a.

It is a figure which shows the resin-made sheet | seat used for one Embodiment of this invention, (a) is a top view of the resin-made sheet in which the opening part was formed, (b) is the plane of the resin-made sheet in which the opening part is not formed. Figure. The top view of a heat press board similarly. It is a figure which shows the process of sandwiching the laminated resin sheet | seat between hot press plates, and heat-pressing, (a) Side surface sectional drawing which shows the state before applying a pressure, (b) is the side surface of the state which applied the pressure Sectional drawing. The perspective view of the same rigid-flexible substrate. It is a figure which shows the manufacturing process of the rigid-flexible board | substrate by the conventional method, (a) is side sectional drawing which shows the state before applying a pressure, (b) is side sectional drawing of the state which applied the pressure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin sheet | seat 1a in which opening part was formed Opening part 2 Resin sheet | seat 3 in which opening part is not formed 3 Conductor pattern 7 Conductor pattern 9 Positioning round hole 10 Positioning long hole 11 Upper heat press board 11b Projection part 12 Lower heat press board 12b Projection portion 13 Positioning pin 14 Positioning pin 17 Sheet-like cushioning material 18 Sheet-like cushioning material 50 Rigid-flexible substrate 50f Flexible portion 50r Rigid portion

Claims (4)

A method for producing a printed circuit board having a rigid part and a flexible part by laminating a plurality of resin sheets having a conductor pattern and welding them by hot pressing,
Preparing a resin sheet having an opening formed at a position corresponding to the flexible part;
A step of preparing a resin sheet having the same size as the resin sheet having an opening prepared in the above step and not forming an opening;
Laminating a plurality of the prepared resin sheets, heating by sandwiching them with a hot press plate from above and below, and welding the resin sheets to each other,
The hot press plate has a protrusion having the same size as the opening, and when the resin sheet is sandwiched, the protrusion fits into the opening and does not form an opening. A method of manufacturing a printed circuit board having a rigid part and a flexible part, wherein the printed circuit board is in contact with a sheet surface of the sheet.   2. The method of manufacturing a printed circuit board having a rigid portion and a flexible portion according to claim 1, wherein the protrusion of the hot press plate is obtained by fixing a heat resistant member separate from the hot press plate to the surface of the hot press plate. .   In the step of laminating a plurality of the resin sheets, sandwiching and heating the resin sheets from above and below, and welding the resin sheets together, a sheet-like cushioning material is interposed between the resin sheet and the heat press plate The manufacturing method of the printed circuit board which has the rigid part and flexible part of Claim 1 or Claim 2 made to make.   Positioning holes are formed in at least two locations in the resin sheet, and positioning pins are erected on the hot press plate, and when the resin sheet is sandwiched between the hot press plates, the positioning pins The method for manufacturing a printed circuit board having a rigid portion and a flexible portion according to any one of claims 1 to 3, wherein the resin sheet and the hot press plate are aligned by entering the use hole.

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