JP2009277810A - Long-shaped board and board jointing tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a long-shaped board which is conductively connected without using a conductive connection jig or high temperature terminal. <P>SOLUTION: In a board joining tape which is used for a method for carrying out a circuit forming process in the long-shaped board in which an end part of a conductive layer of the board joining tape is conductively connected to a sheet-shaped board surface, and in the long-shaped board obtained by connecting a plurality of sheet-shaped boards having a conductive surface, in the long-shaped board in which the plurality of sheet-shaped boards are connected by the board joining tape composed of at least the conductive layer and a sticky layer, the conductive layer is composed of at least the sticky layer and the sticky layer at the end part is thinner than a central part thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a long substrate in which sheet-like substrates are connected and conductively connected between sheet-like substrates, and a substrate bonding tape used therefor.

  In recent years, flexible substrates have been used in mobile phones, liquid crystal displays, digital cameras, hard disks, and many other electronic devices. Because of its flexibility, it is used for hinges and movable parts, and is indispensable for compactly storing substrates in equipment. However, the conductive sheet-like substrate provided with copper foil or stainless steel on both sides or one side of the insulating layer made of polyester, polyimide, or the like used when manufacturing a flexible substrate is flexible because of its flexibility. In the transportation process, troubles such as winding, dropping, and skewing frequently occur. Therefore, a simple conveyance mechanism used in the production of a rigid printed board having no flexibility cannot convey a sheet-like board for producing a flexible board.

  Furthermore, it is expected that the thickness of the flexible substrate will become thinner in the future, and roll-to-roll processing is required to ensure transportability. However, enormous capital investment is required for roll-to-roll processing in the entire process of manufacturing flexible substrates. Therefore, a manufacturing method has been proposed in which a part of the process is processed with a sheet-like substrate, and then the sheet-like substrate is connected to be processed as a long substrate (for example, see Patent Documents 1 to 3). For example, a sheet-like substrate is laser perforated, and then formed into a roll-like long substrate. As a long substrate, a typical flexible substrate is a flow of separation into a sheet-like substrate after passing through a plating step, a photoresist lamination or coating step, a pattern exposure step, an alkali development step, an etching step, and a resist stripping step. It is a manufacturing workflow.

In this flow, when electrolytic plating is performed in the plating step, it is necessary to electrically connect between the sheet-like substrates of the long substrate. Further, in the photoresist coating process, it is necessary to electrically connect the sheet-like substrates even when the photosensitive resin composition having an ion forming group is applied by electrodeposition. In such a case, a special conductive connection jig may be used. However, attachment / detachment of the conductive connection jig is an operation that requires a large number of steps, which is not preferable from the viewpoint of work efficiency. In addition, a method has been proposed in which a sheet-shaped substrate is conductively connected by pressurizing with a high-temperature terminal from the surface of the substrate bonding tape including the conductive layer and the adhesive layer toward the sheet-shaped substrate (see, for example, Patent Document 4). ). However, there is a problem that the conductive connection takes time because the number of processes increases or a cooling process is necessary.
JP 2004-43848 A JP 2003-342543 A JP 2001-361784 A JP 2007-96037 A

  The subject of this invention is providing the board | substrate bonding tape for forming the elongate board | substrate electrically conductively connected without using a conductive connection jig and a high temperature terminal, and such an elongate board | substrate.

  As a result of the study by the present inventors, the end of the conductive layer of the substrate bonding tape in a long substrate in which a plurality of conductive sheet-like substrates are connected by a substrate bonding tape composed of at least a conductive layer and an adhesive layer. It has been found that the above problem can be solved by a long substrate characterized in that the surface of the substrate and the surface of the sheet-like substrate are conductively connected.

  A substrate bonding tape for use in a method of performing circuit formation processing by connecting a plurality of sheet-like substrates having a conductive surface to form a long substrate, comprising at least a conductive layer and an adhesive layer, It has been found that the above-mentioned problems can be solved by a substrate bonding tape characterized in that the adhesive layer is thinner than the central part.

  According to the present invention, the conductive layer and the sheet-like substrate are brought into contact with each other only by attaching the substrate bonding tape to the sheet-like substrate having a conductive surface without using a conductive connection jig or a high-temperature terminal. Conductive connection between the substrates becomes possible. Further, the conductive connection between the sheet-like substrates is made to obtain a long conductive substrate. As a result, the plating process, the electrodeposition of the photoresist, and the like can be performed on the long substrate. .

  The best mode for carrying out the present invention will be described in detail below. In the present invention, a long substrate is produced by connecting edges in the transport direction of a sheet-like substrate having a conductive surface (hereinafter referred to as a sheet-like substrate) to each other with a substrate bonding tape. 1 and 2 are cross-sectional views of the elongated substrate of the present invention. Edges in the conveyance direction of the sheet-like substrate 2, that is, the front side and the rear side in the conveyance direction are connected to each other by the substrate bonding tape 1. The substrate bonding tape 1 is formed by laminating a conductive layer 3 and an adhesive layer 4, and is attached so that the adhesive layer 4 is in contact with the sheet-like substrate 2. The substrate bonding tape 1 may be attached to both surfaces of the sheet-like substrate 1 (FIG. 2), or may be attached to only one surface (FIG. 1).

  3 and 4 are plan views of the elongated substrate. The substrate bonding tape may be applied over a wide range in the width direction of the edge of the sheet-like substrate 2 (FIG. 3) or may be applied to the end (FIG. 4). That is, any attachment method may be used as long as the conductive connection between the sheet-like substrates is established as long as the conveyance failure due to cutting, deformation, twisting, distortion, or the like does not occur during conveyance.

  The sheet-like substrates are preferably connected so as not to overlap. In actual production, it is difficult to align the edges closely, and it is preferable to connect the sheet-like substrates with a gap therebetween. The interval varies depending on the length, width, sticking method, adhesion to the material, process, etc. of the substrate bonding tape, and thus cannot be defined unconditionally, but is preferably 10 mm or less.

  In the present invention, the substrate bonding tape comprises at least a conductive layer and an adhesive layer. In order to prevent blocking, a release paper or a release film may be provided on the adhesive layer side. Any material may be used for the conductive layer as long as it has conductivity. For example, conductive materials such as metal materials such as copper, silver, aluminum, stainless steel, nichrome, iron, and tungsten, alloys made of copper, iron, chromium, zinc, tin, and the like can be used. The thickness of the conductive layer is preferably 1 to 100 μm. If the thickness is less than 1 μm, the strength may decrease. If the thickness exceeds 100 μm, a large step may be generated on the long substrate, which may cause a conveyance failure.

  Any material may be used for the adhesive layer as long as it has adhesiveness and can be attached to a sheet-like substrate. For example, the adhesive resin which has an acrylic resin, an epoxy resin, a urethane resin, a phenol resin, a silicon resin etc. as a main component is mentioned. You may have characteristics, such as a photocurable photosensitive resin, a photodegradable photosensitive resin, and a thermosetting resin. The thickness of the adhesive layer is preferably 1 to 50 μm. If it is less than 1 μm, the tackiness may be insufficient. If it exceeds 50 μm, the distance between the conductive layer and the surface of the sheet-like substrate may become long, and contact at the end of the conductive layer may be insufficient. In many cases, the substrate bonding tape shown in FIG. 5 and FIG.

  In the substrate bonding tape of the present invention, the adhesive layer at the end of the conductive layer is thinner than the central portion. In the present invention, the end portion of the conductive layer refers to a portion having a width of 1 μm to 1 mm from the end portion of the tape, and the central portion refers to the other portion. The film thickness ratio of the adhesive layer between the center part and the end part is preferably 0 to 90, more preferably 0 to 70, with the 10-point average film thickness of the center part being 100. The state where there is no adhesive layer at the end, that is, the film thickness ratio (end / center) may be 0/100.

  5 to 9 are sectional views showing an example of the substrate bonding tape of the present invention. FIG. 5 or FIG. 6 shows a substrate bonding tape in which the end portion of the conductive layer 3 hangs down to the adhesive layer 4 side. FIG. 7 shows a substrate bonding tape in which the adhesive layer 4 is not formed only at the end of the conductive layer 3. FIG. 8 shows a substrate bonding tape in which the adhesive layer 4 at the end of the conductive layer 3 is formed much thinner than the adhesive layer at the center. Moreover, when the material which heat-shrinks by heating is used for the adhesion layer 4, and it heats at the time of affixing, it will be in the state which the adhesion layer 4 pulled from the edge part of the conductive layer 3 by heat shrink, A substrate bonding tape in which the film thickness of the portion is reduced can also be used. With such a substrate bonding tape, the end portion of the conductive layer 3 can be brought into contact with the sheet-like substrate 2.

  As a means for confirming that the conductive connection of the long substrate is made by contact between the end portion of the conductive layer 3 of the substrate bonding tape 1 and the surface of the sheet-like substrate 2, the substrate bonding tape 1 is attached, As shown in FIG. 9, there is means for peeling only the end of the substrate bonding tape 1. At this time, if the resistance value increases, it is evidence that conductive connection is made between the end of the conductive layer 3 and the surface of the sheet-like substrate 2. Further, when the substrate bonding tape 1 is affixed after an insulating spacer is applied to the end portion of the substrate bonding tape 1, if the resistance value is large, and if there is no spacer, the resistance value is small, this is evidence of conductive connection.

  As shown in FIG. 5 or FIG. 6, the method of forming the sagging of the conductive layer 3 is, for example, when the substrate bonding tape is slit to a predetermined width, the malleability and ductility characteristics of the conductive layer 3 are reduced at the cut portion. The method of using and extending the conductive layer 3 with a cutting blade is mentioned. The substrate bonding tape in which the adhesive layer 4 is not formed only at the end of the conductive layer 3 in FIG. 7 or the method of forming the substrate bonding tape in which the adhesive layer 4 at the end of the conductive layer 3 in FIG. A method of removing the adhesive layer 4 at the end by immersing the end in a solvent or the like, and a method of not applying the adhesive layer 4 to the end in advance. The method for producing the substrate bonding tape may be any means and is not limited thereto.

  The conditions for affixing the substrate bonding tape vary depending on the thickness and material of the conductive layer and the adhesive layer, and the thickness and material of the sheet-like substrate, but cannot be generally specified, but are preferably room temperature to 250 ° C., preferably 0.1 to 0.6 MPa. The pasting time is preferably 1 second to 5 minutes. In particular, the conditions are determined in consideration of the softening point of the adhesive layer and the thermosetting temperature. Any device may be used as the device for connecting the sheet-like substrates with the substrate bonding tape, as long as the material can be securely connected. For example, the device may be pressurized by a roller as described in JP-A No. 2002-223057. A device for heating and pasting can be used.

  The sheet-like substrate according to the present invention is a circuit-forming substrate, for example, a printed circuit board or a lead frame substrate. If it is a printed circuit board, it will be classified into a flexible circuit board and a rigid circuit board, and polyester and polyimide are usually used as an insulating material for a flexible circuit board. The thickness of the insulating layer of the flexible substrate is about 13 to 125 μm, and copper foil or stainless steel of about 12 to 35 μm is provided on both sides or one side thereof, and the substrate bonding tape of the present invention is very flexible. Are preferably used. Also, if it is a rigid substrate, the necessary number of insulating substrates dipped in epoxy resin or phenolic resin on a paper base material or glass base material are stacked, and metal foil is placed on one or both sides, and heated and pressed to laminate The thing which was done is mentioned. In addition, a multilayer shield plate produced by laminating a prepreg, a metal foil, etc. after the inner layer wiring pattern is processed, and a multilayer plate having through holes and via holes are also included. The thickness is about 60 μm to 3.2 mm, and the material and thickness are selected according to the final use form as a printed circuit board. These printed circuit boards include, for example, “Printed Circuit Technology Handbook-Second Edition” (edited by the Printed Circuit Society of Japan, published by Nikkan Kogyo Shimbun) and “Multilayer Printed Circuit Handbook” (JA Scarlet, edited by Co., Ltd.). What is described in Modern Chemical Co., Ltd.) can be used.

  The elongated substrate of the present invention is used for circuit formation of a printed wiring board. The circuit formation process for printed wiring boards includes laser drilling, drilling, desmear, plating, polishing, pickling, dry film photoresist application, liquid resist application, pattern exposure, alkali development, etching, resist stripping, soldering Processes such as resist coating, symbol mark printing coating, laminating, and coverlay film pasting are included.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example.

Example 1
18 μm copper foil (manufactured by Nikko Materials Co., Ltd.) was used as the conductive layer, the epoxy resin coating solution shown in Table 1 was applied, and methyl ethyl ketone was dried to produce a substrate bonding tape having an adhesive layer thickness of 7 μm. . Next, the substrate bonding tape was cut into a width of 15 mm and a length of 50 mm using an all-hydraulic high-speed cutter (manufactured by Yoda Machine Industry Co., Ltd.). It was confirmed with a microscope that the cut substrate bonding tape had a portion where the end of the conductive layer 3 hanged down to the adhesive layer 4 side as shown in FIG.

  Next, 50 mm sides of two sheet-like substrates (50 mm × 100 mm, double-sided copper foil thickness 12 μm, polyimide base material thickness 25 μm) are placed next to each other, and the above-mentioned substrate bonding tape is applied as shown in FIGS. I attached. The electrical conductivity between the sheet-like substrates was measured with an applied voltage of 1 V using an electrometer (trade name: Electrometer 617, manufactured by Keithley Instruments Co., Ltd.). Next, in order to confirm that the end portion of the conductive layer 3 and the surface of the sheet-like substrate 2 are electrically connected, as shown in FIG. It peeled over using the cutter, and it was set as the state which only the center part of the board | substrate joining tape 1 adhere | attached. And when the resistance value between the sheet-like board | substrates 2 was measured, it was the insulated state of 1 M (ohm) or more, and it has confirmed that it was conductively connected by the edge part of the conductive layer 3 of the board | substrate joining tape 1. FIG.

Separately, a large number of through holes were formed in a sheet-like substrate (300 mm × 500 mm, double-sided copper foil thickness 12 μm, polyimide base material thickness 25 μm). Next, the substrate bonding tape having a width of 15 mm and a length of 300 mm was attached to both sides as shown in FIGS. 2 and 3 so that the sides of 300 mm were adjacent to each other. For pasting, a hot roll heated to 180 ° C. was pressed for 1 minute. The connection was repeated, and 30 sheet-like substrates were connected to produce a long substrate. After confirming the conductive connection of the obtained long substrate, it was wound around a metal core to form a roll. Next, the following steps were performed using a roll-to-roll circuit forming apparatus. Copper electroless plating (trade name: Melplate CU-5100, manufactured by Meltex Co., Ltd.) and electroplating (25 ° C., sulfuric acid-copper sulfate aqueous solution) are applied to the long substrate, A copper layer was formed on the surface. Next, a dry film photoresist was laminated, and exposure was performed using a mask film. After peeling off the dry film photoresist support film, alkali development (25 ° C., 1 mass% sodium carbonate aqueous solution) was performed to form a resist pattern. Next, an etching process was performed with a ferric chloride solution (40 ° C., spray pressure: 3.0 kg / cm ² ). Next, the resist was stripped with a 3% by mass aqueous sodium hydroxide solution (50 ° C., spray pressure: 3.0 kg / cm ² ). In all steps, the substrate bonding tape was not cut or peeled off, and a good circuit pattern could be produced.

(Example 2)
18 μm copper foil (manufactured by Nikko Materials Co., Ltd.) was used as the conductive layer, the epoxy resin coating solution shown in Table 1 was applied, and methyl ethyl ketone was dried to produce a substrate bonding tape having an adhesive layer thickness of 7 μm. . Next, the substrate bonding tape was cut into a width of 15 mm and a length of 50 mm in the same manner as in Example 1. And the edge part of the adhesion layer was immersed in methyl ethyl ketone, and the board | substrate joining tape in which the adhesion layer 4 was not formed only in the edge part 0.5 mm width part of the conductive layer 3 as shown in FIG. 7 was produced.

  Next, 50 mm sides of two sheet-like substrates (50 mm × 100 mm, double-sided copper foil thickness 12 μm, polyimide base material thickness 25 μm) are placed next to each other, and the above-mentioned substrate bonding tape is applied as shown in FIGS. The continuity between the sheet-like substrates was measured in the same manner as in Example 1, and was less than 1Ω, confirming the conductive connection. Further, in order to confirm the conduction at the end portion of the conductive layer, the end value of the substrate bonding tape was peeled off in the same manner as in Example 1, and the resistance value was set such that only the central portion of the substrate bonding tape was adhered. As a result, it was confirmed that it was in an insulated state of 1 MΩ or more and was electrically connected at the end of the conductive layer.

Separately, a large number of through holes were formed in a sheet-like substrate (300 mm × 500 mm, double-sided copper foil thickness 12 μm, polyimide base material thickness 25 μm). Next, the substrate bonding tape having a width of 15 mm and a length of 300 mm is arranged so that the sides of 300 mm are adjacent to each other, as shown in FIGS.
Pasted on both sides. The pasting was performed by pressing a hot roll heated to 180 ° C. for 1 minute. The connection was repeated, and 30 sheet-like substrates were connected to produce a long substrate. After confirming the conductive connection of the obtained long substrate, it was wound around a metal core to form a roll. Next, the following steps were performed using a roll-to-roll circuit forming apparatus. Electroless plating of copper (trade name: Melplate CU-5100, manufactured by Meltex Co., Ltd.) and electroplating (25 ° C., sulfuric acid-copper sulfate aqueous solution) is applied to the long substrate, A copper layer was formed on the surface. Next, a dry film photoresist was laminated, and exposure was performed using a mask film. After peeling off the dry film photoresist support film, alkali development (25 ° C., 1 mass% sodium carbonate aqueous solution) was performed to form a resist pattern. Next, an etching process was performed with a ferric chloride solution (40 ° C., spray pressure: 3.0 kg / cm ² ). Next, the resist was stripped with a 3% by mass aqueous sodium hydroxide solution (50 ° C., spray pressure: 3.0 kg / cm ² ). In all steps, the substrate bonding tape was not cut or peeled off, and a good circuit pattern could be produced.

(Comparative example)
18 μm copper foil (manufactured by Nikko Materials Co., Ltd.) was used as the metal layer, and was cut into a width of 15 mm and a length of 50 m. A dry film resist (made by Asahi Kasei Electronics Co., Ltd., trade name: Sunfort AQ2575, thickness 25 μm) having a width of 15 mm and a length of 50 m was attached thereto to produce a substrate connecting tape. When confirmed with a microscope, it was confirmed that the adhesive layer at the end of the conductive layer was not thinner than the central portion.

  Next, the 50 mm sides of two sheet-like substrates (50 mm × 100 mm, double-sided copper foil thickness 12 μm, polyimide base material thickness 25 μm) are placed next to each other, and the above-mentioned substrate bonding tape is applied as shown in FIGS. In addition, when the continuity between the sheet-like substrates was measured in the same manner as in Example 1, it was 1 MΩ or more, and it was confirmed that the sheet was insulated.

  Next, using a replacement iron tip (product name: FX-951 replacement iron tip T12-BC3 3BC type, manufactured by Hakuko Co., Ltd.) as a terminal for pressurization, a 1N load is applied to the surface of the substrate connecting tape. To the sheet-like substrate material for 15 seconds. When the continuity between the sheet-like substrates was measured in the same manner as in Example 1, it was less than 1Ω, and the conductive connection was confirmed.

  A circuit board was produced in the same manner as in Example 1 using the produced long substrate, and a good circuit board was produced in the same manner. However, in the comparative example, a step of pressing the terminal for pressurization to establish conduction was essential.

  INDUSTRIAL APPLICABILITY The present invention can be used in a field where thin sheet-like substrates such as circuit boards and lead frames are connected and processed as a long substrate electrically connected.

Sectional drawing of the elongate board | substrate of this invention. Sectional drawing of the elongate board | substrate of this invention. The top view of the elongate board | substrate of this invention. The top view of the elongate board | substrate of this invention. Sectional drawing of the board | substrate joining tape of this invention. Sectional drawing of the board | substrate joining tape of this invention. Sectional drawing of the board | substrate joining tape of this invention. Sectional drawing of the board | substrate joining tape of this invention. Sectional drawing which showed the state which floated the edge part of the conductive layer from the sheet-like board | substrate, when confirming whether the edge part of a conductive layer and the sheet-like board | substrate were conductively connected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate joining tape 2 Sheet-like board | substrate 3 Conductive layer 4 Adhesive layer

Claims (2)

  In a long substrate in which a plurality of sheet-like substrates having a conductive surface are connected by a substrate bonding tape comprising at least a conductive layer and an adhesive layer, the end of the conductive layer of the substrate bonding tape and the surface of the sheet-like substrate are A long substrate characterized by being conductively connected.   A substrate bonding tape for use in a method of performing a circuit forming process on a long substrate in which a plurality of conductive sheet-like substrates are connected to each other, comprising at least a conductive layer and an adhesive layer. A substrate bonding tape characterized by being thinner than the central portion.

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