JP2010141216A - Laminate for flexible printed wiring board, flexible printed wiring board, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate for flexible printed wiring boards, wherein ultra-fine pitch wiring can be efficiently formed and an ultra-fine pitch COF film carrier tape or the like can be used. <P>SOLUTION: The laminate includes an insulating substrate 11 having a through hole 13 for conduction formed therein and a conductor layer 14 bonded to one surface of the insulating substrate 11, and a buried conductor plating layer 15 is provided in the through hole 13 for conduction so that a top surface of the buried conductor plating layer 15 is level with the surface of the insulating substrate 11, and a conductor plating layer 18 covering the surface of the insulating substrate 11 and the top surface of the buried conductor plating layer 15 is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board laminate that can be used for a COF film carrier tape and the like, a flexible printed wiring board, and methods for producing the same.

  A three-layer TAB tape in which a wiring pattern formed from an insulating film, an adhesive layer, and a conductive metal foil is formed, or a two-layer structure COF in which a wiring pattern made of a conductive metal foil is directly formed on an insulating film The output-side outer lead and the input-side outer lead of a printed wiring board such as a tape are electrically connected to a circuit portion of a liquid crystal panel or a rigid printed wiring board, for example, by an anisotropic conductive film (ACF). .

  In recent years, as the fine pitch of the gold bumps on the driver IC chip has increased with the increase in the resolution of the liquid crystal screen, a circuit in which the inner lead pitch is thinned to 20 μm or less is formed on the printed wiring board for IC mounting such as COF. Is becoming necessary, and a pitch of 15 μm has entered the field of view.

  In responding to such high-definition wiring, recently, a technique for forming an ultrafine pitch wiring pattern by a semi-additive method has been attracting attention. Issues such as how to ensure accuracy remain.

  On the other hand, a method corresponding to a fine pitch is also being studied by arranging a printed wiring board with a two-metal structure and arranging a wiring pattern on the back side.

  For example, a through-hole is formed in a double-sided copper-clad laminate with a die or a drill, electroless copper plating is applied to the inner peripheral wall surface of the through-hole, and further copper electroplating is performed to achieve conduction between the front and back copper layers, Although a method of forming a pattern by photolithography has been studied, there is a problem that the wiring between the through-hole lands has a fine pitch, and the meaning of the two-metal structure is small.

  Therefore, a method of filling the through hole with copper plating has been proposed (see Patent Document 1). This method is a method of filling the opening with copper plating by performing electrolytic copper plating after forming an opening in the insulating layer by laser or etching, while forming a wiring pattern. Since this is a process of forming an opening and laminating, there is a problem that the process becomes complicated.

  On the other hand, a method has been proposed in which a via hole for double-sided conduction is formed on an insulating film having an adhesive layer and a copper foil is bonded to the insulating film, and then a via hole is filled and plated to form a blind via hole (Patent Document 2). reference).

  However, in this method, after filling and plating to a depth of about ½ of the via hole, half of the via hole is filled when forming the copper plating layer on one side, so that the surface of the copper plating layer is completely flat In other words, there is a problem that the formation of fine pitch wiring is hindered.

JP 2001-156453 A JP 2005-217216 A

  In view of the above-described circumstances, the present invention can efficiently form ultrafine pitch wiring, and can be used for an ultrafine pitch COF film carrier tape, etc., a laminate for a flexible printed wiring board, a flexible printed wiring board, and these An object is to provide a manufacturing method.

  A first aspect of the present invention that achieves the above object comprises an insulating base material in which a through hole for conduction is formed, and a conductor layer bonded to one surface of the insulating base material. A buried conductor plating layer is provided in the hole so that an upper surface thereof is flush with a surface of the insulating base material, and a conductor plating layer covering the surface of the insulating base material and the upper surface of the embedded conductor plating layer is provided. It is in the laminated body for flexible printed wiring boards characterized by being provided.

  In the first aspect, a two-metal structure can be formed using an insulating base material in which a through hole for conduction is easily formed by punching or the like, and the upper surface of the embedded conductor plating layer embedded in the through hole for conduction is an insulating group. Since the conductor plating layer formed on the surface of the material is flat, the printed wiring board is also flat, and when a printed wiring board is used, a wiring pattern is formed in which fine-pitch wiring is efficiently arranged between through holes for conduction. It becomes possible to do.

  According to a second aspect of the present invention, in the laminate for a flexible printed wiring board according to the first aspect, the through holes for conduction are provided with a diameter of 30 to 800 μm and a pitch of 60 to 1600 μm. A laminate for a flexible printed wiring board characterized by the above.

  In the second aspect, a two-metal structure in which a conductive wiring is formed in which conductive through holes provided with a predetermined diameter and a predetermined pitch are embedded by an embedded conductive plating layer so that the upper surface is flush with each other. It becomes a laminated body for flexible printed wiring boards.

  According to a third aspect of the present invention, in the laminate for a flexible printed wiring board according to the first or second aspect, the embedded conductor plating layer has a copper sulfate pentahydrate concentration of 50 to 90 g / L. PPR (periodic reverse current) using a plating solution having a sulfuric acid concentration of 180 to 210 g / L and a current density ratio of applied pulses in the range of positive: negative = 1: 1.2 to 1: 1.8. The laminate for a flexible printed wiring board is characterized by being formed by a pulse) plating method.

  In the third aspect, the copper plating layer to be the buried conductor plating layer is formed by PPR plating under a predetermined condition, so that the upper surface is more surely flat and is flush with the surface of the insulating substrate. A conductor plating layer can be formed more simply.

  According to a fourth aspect of the present invention, in the laminate for a flexible printed wiring board according to the third aspect, the pulse application time applied in the formation of the embedded conductor plating layer is set to a positive value of 18 to 22 msec and a negative value. It is in the laminated body for flexible printed wiring boards characterized by being 0.5-1.5 msec.

  In the fourth aspect, by setting the pulse of the PPR method to a predetermined pulse, it is possible to more reliably form an embedded conductor plating layer having a flat upper surface.

  According to a fifth aspect of the present invention, in the flexible printed wiring board laminate according to any one of the first to fourth aspects, the embedded conductor plating layer has a flattened upper surface after polishing by polishing. It is in the laminated body for flexible printed wiring boards characterized by the above-mentioned.

  In the fifth aspect, the upper surface can be more reliably flattened by performing a polishing process after plating a copper plating layer to be an embedded conductor plating layer.

  According to a sixth aspect of the present invention, in the laminate for a flexible printed wiring board according to any one of the first to fifth aspects, the insulating base material includes a heat radiating through hole, and the heat radiating through hole. Is provided with a buried heat-dissipating plating layer formed together with the buried conductor plating layer.

  In the sixth aspect, the heat generated from the wiring can be radiated to the back surface side by providing the buried plating layer in the heat radiating through hole.

  A seventh aspect of the present invention is formed using the flexible printed wiring board laminate according to any one of the first to sixth aspects, and a wiring pattern is formed on each of the conductor layer and the conductor plating layer. The flexible printed wiring board is characterized in that is formed.

  In the seventh aspect, the upper surface of the embedded conductor plating layer formed using the insulating base material that is easily formed by punching the through hole for conduction and embedded in the through hole for conduction is the surface of the insulating base material. Since a laminate having a flat two-metal structure is used, a flexible printed wiring board having a wiring pattern in which fine pitch wiring is efficiently arranged between through holes for conduction is obtained.

  According to an eighth aspect of the present invention, in the flexible printed wiring board according to the seventh aspect, the wiring pitch (line and space) of the terminal portion of the wiring pattern is 30 μm or less, the line width (line) is 6 μm or more, The flexible printed wiring board is characterized in that an interval (space) between the wirings is 15 μm or less.

  In the eighth aspect, a flexible printed wiring board having fine pitch wiring within a predetermined range is obtained.

  A ninth aspect of the present invention includes a step of forming a through hole for conduction in an insulating base material, a step of adhering a conductor layer to one surface of the insulating base material, and an embedded conductor plating in the through hole for conduction Forming a layer so that the upper surface thereof is flush with the surface of the insulating substrate, and providing a conductor plating layer so as to cover the surface of the insulating substrate and the upper surface of the embedded conductor plating layer; In the manufacturing method of the laminated body for flexible printed wiring boards characterized by comprising.

  In the ninth aspect, a two-metal structure can be formed relatively easily using an insulating base material in which a through hole for conduction is easily formed by punching or the like, and an embedded conductor plating layer embedded in the through hole for conduction is provided. Since the top surface is flush with the surface of the insulating base material, the conductor plating layer formed on it is also flat. When a printed wiring board is used, fine-pitch wiring is efficiently arranged between through holes for conduction. A laminate for a printed wiring board capable of forming a wiring pattern can be manufactured.

  According to a tenth aspect of the present invention, in the method for manufacturing a laminate for a flexible printed wiring board according to the ninth aspect, the through holes for conduction are provided with a diameter of 30 to 800 μm and a pitch of 60 to 1600 μm. The method for producing a laminate for a flexible printed circuit board is characterized in that:

  In the tenth aspect, a two-metal structure in which a conductive wiring in which conductive through holes provided with a predetermined diameter and a predetermined pitch are embedded by an embedded conductive plating layer so that the upper surface is flush with each other is formed. A laminate for a flexible printed wiring board can be manufactured.

  An eleventh aspect of the present invention is the method for producing a laminate for a flexible printed wiring board according to the ninth or tenth aspect, wherein the buried conductor plating layer has a copper sulfate pentahydrate concentration of 50 to 90 g. PPR (period) using a plating solution having a sulfuric acid concentration of 180 to 210 g / L at a flow rate of / L and a current density ratio of applied pulses in the range of positive: negative = 1: 1.2 to 1: 1.8 In the manufacturing method of the laminated body for flexible printed wiring boards, it is formed by a plating method.

  In the eleventh aspect, the copper plating layer to be the buried conductor plating layer is formed by PPR plating under a predetermined condition, so that the upper surface is more surely flat and is flush with the surface of the insulating substrate. A conductor plating layer can be formed more simply.

  According to a twelfth aspect of the present invention, in the laminate for a flexible printed wiring board according to the eleventh aspect, the pulse application time applied in the formation of the embedded conductor plating layer is set to a positive value of 18 to 22 msec and a negative value. It is in the manufacturing method of the laminated body for flexible printed wiring boards characterized by being 0.5-1.5 msec.

  In the eleventh aspect, by setting the pulse of the PPR method to a predetermined pulse, it is possible to more reliably form an embedded conductor plating layer having a flat upper surface.

  According to a thirteenth aspect of the present invention, in the method for manufacturing a laminate for a flexible printed wiring board according to any one of the ninth to twelfth aspects, the embedded conductor plating layer is polished on the upper surface after plating. It is in the manufacturing method of the laminated body for flexible printed wiring boards characterized by forming by flattening.

  In the thirteenth aspect, the upper surface can be more reliably flattened by performing a polishing process after plating a copper plating layer to be an embedded conductor plating layer.

  According to a fourteenth aspect of the present invention, in the method for manufacturing a laminate for a flexible printed wiring board according to any one of the ninth to thirteenth aspects, a heat dissipation through hole is formed in the insulating base material together with the conduction through hole. And forming a buried heat-dissipating plating layer so as to embed the heat-dissipating through-holes when forming the buried conductor plating layer. .

  In the fourteenth aspect, the flexible printed wiring board can dissipate heat generated from the chip component mounted on the embedded heat-dissipating plating layer to the back surface side by providing the embedded heat-dissipating plating layer in the heat-dissipating through hole. Can be produced.

  According to a fifteenth aspect of the present invention, wiring is provided to each of the conductor layer and the conductor plating layer of the laminate for a flexible printed wiring board obtained by the manufacturing method according to any one of the ninth to fourteenth aspects. The method of manufacturing a flexible printed wiring board further includes a step of forming a pattern.

  In the fifteenth aspect, the upper surface of the buried conductor plating layer embedded in the through hole for conduction can be formed using an insulating base material in which the through hole for conduction is easily formed by punching or the like. Since it manufactures using the laminated body of a flat 2 metal structure, the flexible printed wiring board which has a wiring pattern which has arrange | positioned the fine pitch wiring efficiently between the through-holes for conduction | electrical_connection can be manufactured.

  According to a sixteenth aspect of the present invention, in the method for manufacturing a flexible printed wiring board according to the fifteenth aspect, when the wiring pattern is formed, the wiring pitch (line and space) of the terminal portion is 30 μm or less, A flexible printed wiring board manufacturing method is characterized in that a wiring pattern having a width (line) of 6 μm or more and an interval (space) between wirings of 15 μm or less is formed.

  In the sixteenth aspect, a flexible printed wiring board having fine pitch wiring within a predetermined range can be manufactured.

  Hereinafter, an example of a laminate for a flexible printed wiring board and a flexible printed wiring board according to an embodiment of the present invention will be described based on examples.

  FIG. 1 is a cross-sectional view of a laminate for a flexible printed wiring board according to an embodiment, and FIG. 2 is a cross-sectional view of the flexible printed wiring board.

  As shown in FIG. 1, a laminate 10 for a flexible printed wiring board according to this embodiment includes a flexible insulating base 11 and a metal foil bonded to one surface of the insulating base 11 via an adhesive layer 12. A conductive layer 14, an embedded conductor plating layer 15 embedded in a plurality of through holes 13 for conduction formed in the insulating base 11, and a first conductive provided on the other surface side of the insulating base 11. It has a laminated structure including a body plating layer and a conductor plating layer 18 composed of a second conductor plating layer.

  Here, the upper surface of the embedded conductor plating layer 15 is flush with the surface of the insulating substrate 11, and the first plating provided on the surface of the insulating substrate 11 and the upper surface of the embedded conductor plating layer 15. The layer 16 and the second plating layer 17 are completely conductive with the embedded conductor plating layer 15 and are formed flat even in the vicinity of the boundary between the insulating base material 11 and the embedded conductor plating layer 15. Moreover, the 1st plating layer 16 and the 2nd plating layer 17 become the conductor plating layer 18 of a present Example.

  FIG. 2 is a cross-sectional view of a flexible printed wiring board manufactured using such a flexible printed wiring board laminate 10. The flexible printed wiring board 20 forms the first wiring pattern 21 and the second wiring pattern 22 on both surfaces of the insulating base material 11 by patterning the conductor layer 14 and the conductor plating layer 18 by a photolithography process. Thus, the first and second wiring patterns 21 and 22 are appropriately connected via the embedded conductor plating layer 15 to form an integrated wiring pattern.

  Hereinafter, the laminate 10 for the flexible printed wiring board and the flexible printed wiring board 20 will be described in more detail while illustrating the manufacturing method.

  3 and 4 show an example of a method for manufacturing a flexible printed circuit board laminate. As shown in FIG. 1A, first, a laminate in which an adhesive layer 12 is provided on one surface of an insulating base material 11 is prepared.

  Here, the insulating substrate 11 can be used without particular limitation as long as it is used as a normal insulating substrate such as a plate, film, sheet, prepreg made of an insulating resin. However, in order to continuously manufacture the printed wiring board of the present invention in a reel-to-reel method, it is desirable that the insulating base material 11 is long, flexible and flexible, Further, in the process of manufacturing a printed wiring board, the insulating base material 11 is preferably excellent in chemical resistance because it may come into contact with an acidic solution or an alkaline solution, and may be exposed to a high temperature. For this reason, it is desirable to have excellent heat resistance. Moreover, since a wiring pattern is manufactured by a plating process using this insulating base material 11, it is desirable that it is not modified or deformed by contact with water. From this point of view, it is preferable to use a heat-resistant synthetic resin film as the insulating substrate 11 used in the present invention, and in particular, a polyimide film, a polyamideimide film, a polyethylene terephthalate (PET) resin film, a fluororesin film, a liquid crystal polymer. It is preferable to use a resin film that is usually used for the production of a printed wiring board, such as a film, and among these, a polyimide film excellent in characteristics such as heat resistance, chemical resistance, and water resistance is particularly preferable. In the present invention, the insulating substrate 11 is not necessarily in the form of a film as described above, and may be a plate-shaped insulating substrate made of a composite material such as a fibrous material and an epoxy resin.

  The thickness of the insulating substrate 11 is 10 to 100 μm, preferably 20 to 40 μm, and it is preferable to use a heat-resistant resin film manufactured in terms of cost and handling. It is preferable to use a commercially available polyimide film or polyamideimide film as the material. In particular, a wholly aromatic polyimide obtained by polymerization of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether (for example, trade name: Kapton; manufactured by Toray DuPont), biphenyltetracarboxylic acid-2 anhydride, It is preferable to use a polymer with paraphenylenediamine (PPD) (for example, trade name: Upilex S; manufactured by Ube Industries), apical (trade name: manufactured by Kaneka Corporation), and the like.

  The adhesive layer 12 may be formed using, for example, an insulating adhesive such as a polyamide adhesive or an epoxy adhesive, and the thickness is, for example, 5 to 25 μm, preferably 8 to 12 μm. .

  Next, as shown in FIG. 3 (b), a plurality of through holes 13 for conduction are formed in a predetermined arrangement in the laminated body of the insulating base material 11 and the adhesive layer 12. The conduction through-hole 13 may be formed by drilling, punching using a die, laser drilling, or the like, but it is preferable from the viewpoint of cost to form the through-hole 13 for conduction.

  Although illustration is omitted, sprocket holes (or perforation holes) for conveyance or positioning are formed on both sides of the insulating base material 11 in the width direction. These sprocket holes are formed simultaneously with the through holes 13 for conduction. Although it may be formed, it may be formed prior to this step or in another step after this step, and is not particularly limited.

  Next, as shown in FIG.3 (c), the conductor layer 14 is affixed on the one surface side in which the adhesive bond layer 12 of the insulating base material 11 was provided. This affixing is performed, for example, by performing a temporary pressure bonding with a hot roll or the like and then performing a bonding process by heat treatment.

  Here, if the conductor layer 14 consists of metal foil and has thickness and quality which can be used as a flexible printed wiring base material, it will not specifically limit. Generally, a thickness of about 5 to 35 μm is used. Further, from the viewpoint of handling in the manufacturing process, a metal foil with a carrier may be used in the manufacturing process, and the carrier may be finally removed. In addition, examples of the metal foil include copper foil and aluminum foil, and examples of the carrier include copper foil and aluminum foil.

  Next, as shown in FIG. 3D, an embedded conductor plating layer 15 is formed so as to embed the through-holes 13 for conduction. The embedded conductor plating layer 15 may be formed by an electroplating method or the like, but finally it is necessary to form the upper surface so as to be flush with the surface of the insulating base material 11.

  Therefore, after forming the plating layer 15A so as to rise from the surface of the insulating base 11 as shown in FIG. 4A, the upper surface is flushed by chemical polishing or buffing as shown in FIG. 4B. It is good also as plating layer 15B used as follows. The polishing step may be performed after the conductor plating layer is formed on the plating layer 15A. However, in order to form a flat state throughout, the upper surface of the embedded conductor plating layer 15 is insulated. After polishing to be flush with the substrate, it is preferable to provide a conductor plating layer.

  Further, it is not necessary to perform the polishing step by plating so that the upper surface is flush with the PPR (periodic reverse current pulse) plating method.

  Here, when the buried conductor plating layer 15 is formed as a copper plating layer by the PPR plating method, a plating solution having a copper sulfate pentahydrate concentration of 50 to 90 g / L and a sulfuric acid concentration of 180 to 210 g / L is used. It is preferable to perform plating under a plating condition in which the current density ratio of the applied pulse is in the range of positive: negative = 1: 1.2 to 1: 1.8. Thereby, the embedded conductor plating layer 15 can be formed so that the upper surface is flat and flush with the surface of the insulating base material 11. In this case, positive means the direction in which the copper plating adheres to the sample, and negative means the direction in which the copper plating dissolves.

In particular, the pulse to be applied is preferably a pulse having a positive value of 18 to 22 msec and a negative value of 0.5 to 1.5 msec, and the current density is preferably 1 to 4 A / dm ² . By setting it as such plating conditions, the wiring with a flat surface can be formed more reliably.

  Next, as shown in FIG. 3 (e), for example, an electroless plating layer 16 made of nickel is coated on the surface of the insulating substrate 11 and the upper surface of the embedded conductor plating layer 15, for example, 0.01 to It is provided with a thickness of 0.2 μm. In order to form the electroless plating layer 16 more reliably and with good adhesion, it is preferable to perform a plating pretreatment prior to the electroless plating. In this plating pretreatment, for example, the upper surface of the insulating substrate 11 is degreased and subjected to an alkali treatment, and then a base layer containing a catalyst or the like is formed as necessary. For example, when the insulating base material 11 is polyimide, it is preferable to perform pretreatment such as degreasing and alkali modification to open the polyimide ring, and then performing catalytic treatment and then reduction.

  Next, as shown in FIG. 3F, an electroplating layer 17 made of, for example, copper is formed on the electroless plating layer 16 with a thickness of, for example, 1 to 15 μm. Thereby, the conductor plating layer 18 including the electroless plating layer 16 and the electroplating layer 17 is formed.

  Note that when the electroless plating layer 16 and the electroplating layer 17 are formed, the back side needs to be masked with a resist or the like, but either or both of the electroless plating layer 16 and the electroplating layer 17 are used. At the same time, a plating layer may be provided on the back surface.

  In the above-described process, the conductor plating layer 18 is composed of the electroless plating layer 16 and the electroplating layer 17, but the whole may be formed by electroless plating.

In FIG. 5, an example of the manufacturing method of the flexible printed wiring board 20 is shown.
A flexible printed circuit board laminate 10 as shown in FIG. 5A is prepared. As shown in FIG. 5B, a mask resist layer 101 covering the entire conductor layer 14 is provided and the conductor plating layer 18 is provided. A resist pattern layer 102 patterned in a predetermined shape is formed thereon.

  Next, as shown in FIG. 5C, the conductor plating layer 18 is etched using the mask resist layer 101 and the resist pattern layer 102 as a mask, and the mask resist layer 101 and the resist pattern layer 102 are removed. 1 wiring pattern 21 is formed. Note that the first wiring pattern 21 can be electrically connected to the buried conductive plating layer 15 at a necessary location.

  Next, as shown in FIG. 5D, a mask resist layer 103 that covers the first wiring pattern 21 is provided, and a resist pattern layer 104 that is patterned into a predetermined shape is formed on the conductor layer 14.

  Subsequently, as shown in FIG. 5E, the conductor layer 14 is etched using the mask resist layer 103 and the resist pattern layer 104 as a mask, and the mask resist layer 103 and the resist pattern layer 104 are removed, whereby the second The wiring pattern 22 is formed. The second wiring pattern 22 is electrically connected to the first wiring pattern 21 via the buried conductor plating layer 15 at a predetermined location, and the wiring pattern together with the first wiring pattern 21 and the buried conductor plating layer 15. It becomes what constitutes.

  The flexible printed wiring board 20 can be formed by forming a solder resist layer so as to cover at least a part of the wiring patterns 21 and 22 in this way.

  6 and 7 show another example of a method for manufacturing a flexible printed wiring board. Since this manufacturing method is based on a semi-additive method, as shown in FIG. 6A, a flexible printed wiring board laminate 10A having a conductive plating layer 19 with a relatively small thickness was prepared.

  Next, as shown in FIG. 6B, a mask resist layer 111 covering the entire conductor layer 14 is provided, and a resist pattern layer 112 patterned in a predetermined shape is formed on the conductor plating layer 19.

  Next, as shown in FIG. 6C, a semi-additive plating layer 31 is formed in a region where the conductor plating layer 19 is exposed using the mask resist layer 111 and the resist pattern layer 112 as a mask. ), The mask resist layer 111 and the resist pattern layer 112 are removed.

  Next, as shown in FIG. 7 (a), the conductive plating layer 19 is flash-etched using the semi-additive plating layer 31 as a mask, and the semi-additive plating layer 31 and the conductive plating layer pattern of the same pattern as the lower layer are formed. A first wiring pattern 32 made of 19A is formed. The first wiring pattern 32 can be electrically connected to the buried conductive plating layer 15 at a necessary location.

  Next, as shown in FIG. 7B, a mask resist layer 113 covering the first wiring pattern 32 is provided, and a resist pattern layer 114 patterned in a predetermined shape is formed on the conductor layer 14.

  Subsequently, as shown in FIG. 7C, the conductor layer 14 is etched using the mask resist layer 113 and the resist pattern layer 114 as a mask, and the mask resist layer 113 and the resist pattern layer 114 are removed, whereby the second The wiring pattern 33 is formed. The second wiring pattern 33 is electrically connected to the first wiring pattern 32 via the buried conductor plating layer 15 at a predetermined location, and the wiring pattern together with the first wiring pattern 32 and the buried conductor plating layer 15. It becomes what constitutes.

  The flexible printed wiring board 20 can be formed by forming a solder resist layer so as to cover at least a part of the wiring patterns 32 and 33 in this way.

  In the laminate for a flexible wiring board and the flexible wiring board described above, the through-hole for conduction and the embedded conductor plating layer embedded in this have been described. It is also possible to form the embedded heat-dissipating plating layer so as to embed the heat-dissipating through-hole when forming the large-diameter heat dissipating through-hole and forming the embedded conductor plating layer. In this case, for example, heat from an IC chip or the like mounted on the surface-side wiring pattern (including the embedded heat dissipation plating layer) is provided in the IC chip mounting region and the heat dissipation through hole in the periphery thereof. There is an effect that heat can be radiated to the back surface side through the buried plating layer.

  EXAMPLES Next, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

[Example 1]
A polyamide adhesive was applied to a 10 μm thickness with a roll coater on a polyimide film (product name: Kapton, manufactured by Toray DuPont Co., Ltd.) having a thickness of 37.5 μm as an insulating substrate, dried, and then slit to a width of 35 mm. By punching using a die, 81 heat radiation through holes with a diameter of 0.8 mm at a pitch of 0.8 mm and 100 conduction through holes with a diameter of 0.08 mm at a pitch of 0.17 mm, totaling 181 holes. Formed. At the same time, perforation holes with a diameter of 1.42 mm were formed at both ends of the film with the same mold at a pitch of 4.75 mm to form a feed guide.

  An electrolytic copper foil (NA-DFF manufactured by Mitsui Kinzoku Mining Co., Ltd.) having a thickness of 15 μm and a width of 30 mm is temporarily bonded to such an insulating substrate as a conductor layer, and then heated to completely Glued.

Next, the laminated body of the insulating substrate and the conductor layer was treated with hydrochloric acid to be acid degreased, and a cover plating-containing copper plating solution (manufactured by Meltex; CuSO ₄ .5H ₂ O: 110 gr / L, sulfuric acid 190 gr / L L, Cl ^- 50 ppm) was used, plating was performed at a temperature of 25 ° C., a current density of 4 A / dm ² for 57 minutes, with a plating thickness of 50 μm, and the heat radiating through hole and the conductive through hole were embedded with an embedded copper plating layer. The buried copper plating layer was about 2 μm higher than the surface of the insulating substrate.

  Thereafter, the upper surface of the buried copper plating layer protruding from the surface of the insulating base material is polished with a water-resistant silicon carbide paper (manufactured by Marumoto Struers, FEPA P # 2400) with a rotary polishing apparatus 360 times / minute for insulation. It was made to be flush with the surface of the substrate.

  Next, the surface of the insulating substrate is subjected to alkaline degreasing treatment, ring-opening treatment with alkali, catalytic treatment and further reduction treatment, and then electroless nickel plating (manufactured by Ebara Densan Co., Ltd.) is performed at 38 ° C. for 5 minutes. Then, a nickel plating layer having a thickness of 100 nm was formed on the entire front and back surfaces of the insulating substrate and the buried copper plating layer.

Furthermore, after removing water by heating at 130 ° C. for 5 minutes and further performing copper replacement treatment, a copper plating solution containing cover grease (Meltex; CuSO ₄ .5H ₂ O: 110 gr / L, sulfuric acid 190 gr / L L, Cl ^- 50 ppm), plating at a liquid temperature of 24 ° C. and a current density of 3 A / dm ² for 15 minutes, forming a 10 μm thick copper plating layer on the nickel plating layer, and laminating for a flexible printed circuit board The body. At this time, the copper foil surface on the back surface was protected by pressing against the back plate made of vinyl chloride to prevent the plating solution from flowing in, so that the copper plating did not adhere.

  Next, a negative dry film resist (M-50B, manufactured by Asahi Kasei Co., Ltd.) having a thickness of 15 μm is pasted at 105 ° C. using a laminator on the front and back surfaces of the laminate for a flexible printed wiring board thus manufactured. It was.

Next, the electrolytic copper foil side dry film resist on the front side was exposed to UV light at an exposure amount of 180 mJ / cm ² by an exposure apparatus using a glass mask on which a wiring pattern having a pitch of 20 μm to 460 μm was drawn, The dry film resist was exposed to the entire surface with ultraviolet light at an exposure amount of 180 mJ / cm ² . Then, it developed with the sodium carbonate solution, the unexposed part was melt | dissolved, and the photoresist pattern of each pitch was formed.

  After development, the electrolytic copper foil exposed from the photoresist pattern was etched with an etching solution, and then the resist layers on both the front and back surfaces were peeled off with a stripping solution to form a first wiring pattern on the surface side.

  Next, similarly, dry film resist is laminated on both sides, the entire surface of the dry film resist on the front side is exposed, the dry film resist on the back side is exposed to a predetermined pattern and developed, and the plating layer on the back side is chlorinated. A second wiring pattern is formed by etching with a second copper etchant, and then the front and back resists are stripped with a stripping solution, dipped in a microetching solution, and a nickel plating layer on the upper surface of the back wiring pattern by flash etching. Was removed. This flash etching requires only a short time because the electroless nickel plating layer is as thin as 100 nm, and therefore has almost no effect on the line width of the wiring pattern.

  And electroless tin plating was formed in 0.5 micrometer thickness on the wiring pattern, and it was set as the flexible printed wiring board.

[Example 2]
As in Example 1, a 37.5 μm-thick polyimide film (trade name: Kapton, manufactured by Toray DuPont Co., Ltd.) was used as the insulating substrate, and the laminate with the electrolytic copper foil was treated in the same manner as in Example 1. After the formation, an embedded copper plating layer is similarly formed in the through hole for conduction, the upper surface is similarly polished, and pretreatment is performed in the same manner as in Example 1, followed by electroless nickel plating (manufactured by Ebara Densan) 38 This was carried out at 5 ° C. for 5 minutes, and a nickel plating layer having a thickness of 100 nm was formed on the entire surface of the insulating substrate and the buried copper plating layer.

Subsequently, after removing moisture by heating at 130 ° C. for 5 minutes, and further performing a copper replacement treatment, a copper plating solution containing cover grease (Meltex Co., Ltd .; CuSO ₄ .5H ₂ O: 75 gr / L, sulfuric acid 200 gr) / L, Cl ^- 50ppm), plating at a liquid temperature of 24 ° C. and a current density of 2 A / dm ² for 30 seconds to form a copper plating layer having a thickness of 0.2 μm on the nickel plating layers on both sides, It was set as the laminated body for flexible printed wiring boards.

  Next, a negative dry film resist (M-50B, manufactured by Asahi Kasei Co., Ltd.) having a thickness of 15 μm is pasted at 105 ° C. using a laminator on the front and back surfaces of the laminate for a flexible printed wiring board thus manufactured. It was.

Next, the 0.2 μm thick copper plating layer side dry film resist on the surface side was exposed to ultraviolet rays at an exposure amount of 180 mJ / cm ² by an exposure apparatus using a glass mask on which a wiring pattern having a pitch of 20 μm to 460 μm was drawn. The dry film resist on the back side was exposed to ultraviolet light at an exposure amount of 180 mJ / cm ² . Then, it developed with the sodium carbonate solution, the unexposed part was melt | dissolved, and the photoresist pattern of each pitch was formed.

Subsequently, using a copper plating solution to which ST901 was added (Meltex; CuSO ₄ .5H ₂ O: 75 gr / L, sulfuric acid 200 gr / L) at a liquid temperature of 24 ° C. and a current density of 2 A / dm ² for 20 minutes. Plating was performed to obtain an 8 μm thick copper-plated wiring pattern by a semi-additive method.

  Next, the resist layers on both the front and back surfaces are stripped with a stripping solution, and further treated with a sulfuric acid + hydrogen peroxide-based etching solution at 35 ° C. for 45 seconds, and a 13% sulfuric acid + 13% hydrochloric acid mixed solution without washing with water. For 13 seconds to dissolve the electroless nickel plating layers on both sides, exposing the insulating substrate in the region where the resist has been removed to form a first wiring pattern on the predetermined surface side, and the back side to be electrolyzed A state in which the copper foil is exposed is obtained.

  Next, similarly, dry film resist is laminated on both sides, the entire surface of the dry film resist on the front side is exposed, the dry film resist on the back side is exposed to a predetermined pattern and developed, and the plating layer on the back side is chlorinated. A second wiring pattern is formed by etching with a second copper etchant, and then the front and back resists are stripped with a stripper, and electroless tin plating is formed on the wiring pattern to a thickness of 0.5 μm. A substrate was used.

[Example 3]
As in Example 1, a 37.5 μm-thick polyimide film (trade name: Kapton, manufactured by Toray DuPont Co., Ltd.) was used as the insulating substrate, and the laminate with the electrolytic copper foil was treated in the same manner as in Example 1. Formed.

Next, unlike Example 1, a copper plating solution to which cover grease PPR was added (manufactured by Meltex; CuSO ₄ .5H ₂ O: 75 gr / L, sulfuric acid 200 gr / L), temperature 25 ° C., current density 4A / dm ² , FR current density ratio (positive: negative = 1: 1.5), FR pulse time (positive side 20msec, negative side 1msec), PPR (periodic reverse current pulse) plating for 57 minutes, through for conduction A copper plating layer having a thickness of 48 μm was formed in the hole and the heat radiating through hole. The upper surfaces of the buried copper plating layer and the buried heat-dissipating plating layer in the hole were flush with the surface of the insulating substrate, and flattening by polishing was not performed. A high-speed polarity reversal pulse current output rectifier (PPS-050-1) manufactured by Chuo Seisakusho Co., Ltd. was used as the power source. The anode used was an insoluble electrode in which titanium was coated with iridium oxide. Hereinafter, it was set as the flexible printed wiring board laminated body like Example 1. FIG.

  Moreover, the flexible printed wiring board was manufactured like Example 1 using this laminated body for flexible printed wiring boards.

[Example 4]
As in Example 1, a 37.5 μm-thick polyimide film (trade name: Kapton, manufactured by Toray DuPont Co., Ltd.) was used as the insulating substrate, and the laminate with the electrolytic copper foil was treated in the same manner as in Example 1. Formed.

  Next, PPR plating was performed in the same manner as in Example 3. The plating time was 60 minutes, and a copper plating layer having a thickness of 50 μm was formed in the through hole for conduction and the through hole for heat dissipation. The upper surfaces of the buried copper plating layer and the buried heat-dissipating plating layer in the hole were raised about 2.5 μm from the surface of the insulating substrate, but the upper surface was flat.

  The buried copper plating layer and the buried heat dissipation plating layer were polished in the same manner as in Example 1 to be flush with the surface of the insulating base material, and then a flexible printed wiring board laminate was obtained in the same manner as in Example 1. .

  Moreover, the flexible printed wiring board was manufactured like Example 1 using this laminated body for flexible printed wiring boards.

[Example 5]
As in Example 1, a 37.5 μm-thick polyimide film (trade name: Kapton, manufactured by Toray DuPont Co., Ltd.) was used as the insulating substrate, and the laminate with the electrolytic copper foil was treated in the same manner as in Example 1. Formed.

  Next, PPR plating was performed in the same manner as in Example 3 to form a 48 μm thick copper plating layer in the through hole for conduction and the through hole for heat dissipation. Since the upper surfaces of the buried copper plating layer and the buried heat-dissipating plating layer in the hole were flush with the surface of the insulating base material, the laminate for the flexible printed wiring board was performed in the same manner as in Example 2 except that polishing was not performed. Got the body.

  Moreover, the flexible printed wiring board was manufactured like Example 2 using this laminated body for flexible printed wiring boards.

[Example 6]
As in Example 1, a 37.5 μm-thick polyimide film (trade name: Kapton, manufactured by Toray DuPont Co., Ltd.) was used as the insulating substrate, and the laminate with the electrolytic copper foil was treated in the same manner as in Example 1. Formed.

  Next, PPR plating was performed for 60 minutes in the same manner as in Example 4 to form a copper plating layer having a thickness of 50 μm in the through hole for conduction and the through hole for heat dissipation. The upper surfaces of the buried copper plating layer and the buried heat-dissipating plating layer in the hole were raised about 2.5 μm from the surface of the insulating substrate, but the upper surface was flat.

  After this embedded copper plating layer was polished in the same manner as in Example 1 to be flush with the surface of the insulating substrate, a flexible printed wiring board laminate was obtained in the same manner as in Example 2.

  Moreover, the flexible printed wiring board was manufactured like Example 2 using this laminated body for flexible printed wiring boards.

(Summary)
When the laminates for flexible printed wiring boards of Examples 1 to 6 are used, the surface of the conductive plating layer becomes flat and the photoresist can be applied with a uniform thickness, so that the exposure ultraviolet rays are irradiated at right angles to the resist surface. Thus, a flexible printed wiring board having a wiring pattern with good exposure accuracy, uniform line width, and high alignment accuracy is obtained.

  Therefore, the land which becomes the connecting portion between the copper plated layer embedded in the through hole for conduction and the wiring can have the same diameter as the diameter of the through hole, and the diameter for the conduction of 0.08 mm in pitch between the holes is 0.09 mm. It is possible to arrange four wires having a line width of 10 μm (pitch of 20 μm) between the through holes.

  If the conductor plating layer on the through hole for conduction is not flat like the conventional laminate for a wiring board, the connection land must be expanded to a diameter of about 0.12 mm, for example. Under the condition, it was the limit to arrange two wirings having a line width of 10 μm (pitch of 20 μm).

It is a schematic sectional drawing of the laminated body for flexible printed wiring boards which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the flexible printed wiring board concerning one Embodiment of this invention. It is a schematic sectional drawing which shows the manufacturing process of the laminated body for flexible printed wiring boards which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the modification of the manufacturing process of the laminated body for flexible printed wiring boards which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the manufacturing process of the flexible printed wiring board which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the manufacturing process of the flexible printed wiring board which concerns on other embodiment of this invention. It is a schematic sectional drawing which shows the manufacturing process of the flexible printed wiring board which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated body for flexible printed wiring boards 11 Insulating base material 12 Adhesive layer 13 Conducting through-hole 14 Conductor layer 15 Embedded conductor plating layer 16 Electroless plating layer 17 Electroplating layer 18 Conductor plating layer 20 Flexible printed wiring board 21 First wiring pattern 22 Second wiring pattern

Claims (16)

  An insulating base material in which a through hole for conduction is formed; and a conductor layer bonded to one surface of the insulating base material. For a flexible printed wiring board, characterized in that a conductor plating layer is provided so as to be flush with the surface of the substrate, and covers the surface of the insulating substrate and the upper surface of the embedded conductor plating layer. Laminated body.   2. The laminate for a flexible printed wiring board according to claim 1, wherein the through holes for conduction are provided with a diameter of 30 to 800 [mu] m and a pitch of 60 to 1600 [mu] m. body.   The laminate for a flexible printed wiring board according to claim 1 or 2, wherein the embedded conductor plating layer is plated with a copper sulfate pentahydrate concentration of 50 to 90 g / L and a sulfuric acid concentration of 180 to 210 g / L. It is formed by a PPR (periodic reverse current pulse) plating method using a solution and setting the current density ratio of the pulse to be applied in the range of positive: negative = 1: 1.2 to 1: 1.8. A laminate for a flexible printed wiring board, characterized in that it is present.   In the laminate for a flexible printed wiring board according to claim 3, the application time of a pulse applied in forming the embedded conductor plating layer is 18-22 msec for positive and 0.5-1.5 msec for negative. A laminate for a flexible printed wiring board characterized by the above.   The laminate for a flexible printed wiring board according to any one of claims 1 to 4, wherein the embedded conductor plating layer is obtained by planarizing an upper surface after plating by a polishing process. Laminated body for flexible printed wiring board.   The laminate for a flexible printed wiring board according to any one of claims 1 to 5, wherein the insulating base material includes a heat radiating through hole, and the heat radiating through hole includes the embedded conductor plating layer and A laminate for a flexible printed wiring board, comprising a buried heat-dissipating plating layer formed together.   It is formed using the laminated body for flexible printed wiring boards of any one of Claims 1-6, and the wiring pattern is formed in each of the said conductor layer and the said conductor plating layer, It is characterized by the above-mentioned. Flexible printed wiring board.   8. The flexible printed wiring board according to claim 7, wherein the wiring pitch of the terminal portions of the wiring pattern is 30 μm or less, the line width is 6 μm or more, and the interval between the wirings is 15 μm or less. .   A step of forming through holes for conduction in the insulating base material, a step of adhering a conductor layer to one surface of the insulating base material, a conductive plating layer embedded in the through hole for conduction, and the top surface of the insulating base material And a step of forming a conductor plating layer so as to cover the surface of the insulating base and the upper surface of the embedded conductor plating layer. A method for producing a laminate for a printed wiring board.   10. The method of manufacturing a laminate for a flexible printed wiring board according to claim 9, wherein the through holes for conduction are provided with a diameter of 30 to 800 [mu] m and a pitch of 60 to 1600 [mu] m. A method for manufacturing a laminate for a substrate.   In the manufacturing method of the laminated body for flexible printed wiring boards of Claim 9 or 10, the said embedded conductor plating layer has a sulfuric acid density | concentration of 180-210 g / L with the density | concentration of 50-90 g / L of copper sulfate pentahydrate. Using a plating solution of L, the PPR (periodic reverse current pulse) plating method is used in which the current density ratio of the pulse to be applied is in the range of positive: negative = 1: 1.2 to 1: 1.8. The manufacturing method of the laminated body for flexible printed wiring boards characterized by the above-mentioned.   The laminate for a flexible printed wiring board according to claim 11, wherein the pulse application time applied in forming the buried conductor plating layer is 18 to 22 msec for positive and 0.5 to 1.5 msec for negative. The manufacturing method of the laminated body for flexible printed wiring boards characterized by these.   In the manufacturing method of the laminated body for flexible printed wiring boards of any one of Claims 9-12, The said embedded conductor plating layer is formed by planarizing the upper surface after plating by polishing process, It is characterized by the above-mentioned. The manufacturing method of the laminated body for flexible printed wiring boards to do.   The method for manufacturing a flexible printed wiring board laminate according to any one of claims 9 to 13, wherein a heat dissipation through hole is formed together with the conduction through hole in the insulating base material, and the embedded conductor plating is performed. A method for producing a laminate for a flexible printed wiring board, comprising forming a buried heat-dissipating plating layer so as to embed the heat-dissipating through-holes when forming the layer.   The process of forming a wiring pattern in each of the said conductor layer of the laminated body for flexible printed wiring boards obtained by the manufacturing method of any one of Claims 9-14, and the said conductor plating layer is further comprised. A method for producing a flexible printed wiring board, comprising: 16. The method of manufacturing a flexible printed wiring board according to claim 15, wherein, when forming the wiring pattern, the wiring pitch of the terminal portion is 30 μm or less, the line width is 6 μm or more, and the interval between the width lines is 15 μm or less. A method of manufacturing a flexible printed wiring board, comprising forming a wiring pattern.

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