JP2005347732A - Method for forming wiring on substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring formation method for forming a wiring pattern on a substrate by using a printing method. <P>SOLUTION: A method for forming wiring on a substrate comprises a process of preparing a copper substrate, a process of forming a copper-nickel layer on a portion of the copper substrate by plating, a process of bonding the copper substrate to a soft polyamide substrate, and a process of etching the copper substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for forming wiring on a substrate, and more particularly to a method for printing wiring on a substrate.

  Currently, a liquid crystal display (LCD), ie, 1) a tape carrier package (TCP), 2) a chip on flex (COF), 3) a drive IC (integrated circuit) on a chip on glass (COG) There are three ways to encapsulate. The first and second methods require a soft circuit board that functions as a carrier substrate to bond the glass plate and the printed circuit board (PCB) on the display. Soft circuit boards for drive ICs are divided into three types.

  First Soft Circuit Board Referring to FIGS. 1A and 1B, the first layer at the bottom is a copper layer 51. The second layer is an adhesive layer 52, and the third layer is a soft polyamide (PI) layer 53. In particular, the structure shown in FIG. 1B is the same as that shown in FIG. 1A, except that the adhesive layer 52 is attached to the free side of the polyamide layer 53, and the first copper layer 51 is the free of the second copper layer 52a. It is attached to the side. During the formation of the wiring on the copper layer 51 for the etching process necessary to form the wiring on the copper layer 51, the thickness of the copper layer 51 is at least 12 μm so that the effective product yield is high. There must be. However, when the thickness of the copper layer is large, it is very difficult to make an elongated wiring. For example, when the thickness of the copper layer is large and the wiring has an average pitch of 40 to 50 μm (width 25 μm, intermediate 20 μm), the product yield decreases. This is due to the fact that today's industry standard is in the 45 μm pitch range. That is, a thin copper foil easily wrinkles during the wiring formation process, resulting in a high defect rate and high cost.

  Second Soft Circuit Board Referring to FIGS. 2A and 2B, there is no adhesive layer compared to the example of FIGS. 1A and 1B. The illustrated structure includes, as a polyamide substrate 54, a monel layer (nickel and copper alloy layer) on the surface of the polyamide substrate and a copper layer 55 attached to the monel layer. Thereafter, the thickness of the copper layer 55 is controlled by plating to reach 6 or 9 μm. In this method, it is not necessary to press the copper foil against the polyamide substrate 54 so that the effective yield is high in a small pitch electric circuit configuration smaller than 40 μm. Furthermore, due to the thickness of the copper foil being controlled by plating, the operator can make the required pitch and width wiring, often reaching a standard well below 30 μm. However, since there is no adhesive layer used to bond the metal layer and the soft polyamide substrate, the metal layer sometimes peels from the substrate. Furthermore, the plated copper layer is easily broken and the reliability of the encapsulated element is not satisfactory. A further disadvantage is that the Monel and Chromium layers are not easily etched away for good chemical adhesion to the PI film, resulting in electrical leakage.

  Third Soft Circuit Board A third soft polyamide board is obtained by applying polyamide (PI) directly to the copper foil to make a board similar to a board without an adhesive layer. However, this type of substrate has a problem that it cannot be applied to the shrinkage of the copper foil thickness in the curing process or a thickness below 12 μm. As a result, the product is not marketable. In order to overcome this drawback, the present invention provides an improved wiring formation method that provides a solution to the above problems.

  A main object of the present invention is to provide an improved wiring forming method using a printing method in order to form a wiring pattern on a substrate. Due to the flat surface and rigidity of the substrate, the wiring pattern is given good support from the substrate and does not break easily during the curing process.

  Another object of the present invention is to form a dry fill before plating a copper-nickel layer on a copper substrate.

  Still another object of the present invention is to etch the entire copper substrate in the etching step.

  Other objects and novel features of the present invention will become more apparent from the following description with reference to the drawings.

  To achieve the above object, the method of the present invention includes the following steps. That is, preparing a copper substrate, applying a dry film or photoresist process to form a circuit pattern on the substrate, plating a cylinder-nickel layer on a portion of the copper substrate, a dry film or a photoresist Removing and heat treating the plated copper substrate to the desired performance, bonding the copper substrate to a soft polyamide substrate, and etching the copper substrate.

  The basic technique of the present invention is to print a wiring pattern on the copper substrate 1. Due to the nature of copper, the copper substrate 1 can provide sufficient support to the wiring after the wiring is formed. Furthermore, because of the flat surface of the copper substrate 1, it is easy to make fine wiring on the substrate, and the effective product yield is improved.

  Referring to FIG. 3, the wiring pattern is printed on the surface of the copper substrate 1. Next, the copper substrate 1 is processed through a dry film process so as to apply a photoresist material 1a to the surface of the copper substrate 1 in order to stop the adhesion of copper and nickel to the copper substrate surface in the copper-nickel plating process. The

  Thereafter, the photoresist material 1a is removed in a cleaning step. The copper substrate 1 provided with the copper-nickel layer 2 on the surface is pressed against the polyamide substrate 3 provided with the adhesive layer 3a in the pressing step. After the pressing process, the copper-nickel layer 2 is ready for wiring, and the substrate is supported by the rigidity of the copper substrate 1, so that shrinkage or expansion during curing does not affect the effectiveness of the wiring.

  Thereafter, a part of the copper substrate 1 is etched by the illustrated step 6A while leaving the copper-nickel layer 2 on the soft polyamide substrate 3 having the adhesive layer 3a, or only a part of the copper substrate is illustrated in the illustrated step. Etching is performed by 6B.

  The difference between steps 6A and 6B depends on the user's selection.

  After passing through the above steps, nickel (Ni), gold (Au) or tin (Sn) is plated, and the welded film 4 is applied to the polyamide substrate 3. Steps 8A and 8B indicate that the integrated circuit (IC) 6 is welded to the wiring according to the present invention by the boss 61.

  In summary, the present invention includes the following steps. That is, preparing a copper substrate, applying a dry film or photoresist process to form a circuit pattern on the substrate, plating a cylinder-nickel layer on a portion of the copper substrate, a dry film or a photoresist Removing and heat treating the plated copper substrate to the desired performance, bonding the copper substrate to a soft polyamide substrate, and etching the copper substrate.

  4A and 4B, the advantages of the present invention are as follows. That is, the wiring is formed on the polyamide substrate, but after the curing process on the copper substrate, the wiring is formed on the copper substrate so that the wiring has good extensibility, electrical conductivity, and elasticity. As a result, the physical phase change of the wiring is supported by the copper substrate, and the product yield is improved.

  During the manufacturing process, the wiring is formed on a copper substrate, and the copper substrate is pressed against a polamide substrate 3 having an adhesive layer, whereby the wiring is buried and protected in the adhesive layer.

  There is no electronic transfer problem. In the COF structure, since there is no metal adhesive layer between the copper substrate and the polyamide substrate, before the cylinder is sputtered, an added adhesive metal such as chromium having a high adhesive force with the polyamide substrate is present. Applied to polyamide substrate. However, during the etching process, the added adhesive metal is not easily removed. According to the method of the present invention, the electron transfer problem is solved.

  The selection of the metal is no longer important because the thin wiring is formed on the highly rigid copper substrate 1 and the copper substrate is pressed against the polyamide substrate 3 having the adhesive layer 3a. As a result, manufacturing costs are small.

Schematic which shows the structure of the conventional three-layer copper substrate. Schematic which shows the structure of the conventional three-layer copper substrate. Schematic which shows the structure of the conventional two-layer copper substrate. Schematic which shows the structure of the conventional two-layer copper substrate. The flowchart which shows the method of this invention. Schematic showing application of a substrate with a wiring pattern according to the present invention. Schematic showing application of a substrate with a wiring pattern according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copper substrate 1a Photoresist material 2 Copper-nickel layer 2
3 Polyamide substrate 3a Adhesive layer 3a

Claims (4)

  A method of forming wiring on a substrate, comprising preparing a copper substrate, performing a dry film or photoresist process to form a circuit pattern on the substrate, and plating a cylinder-nickel layer on a portion of the copper substrate Forming a wiring on a substrate comprising: removing the dry film or photoresist, heat treating the plated copper substrate, bonding the copper substrate to a soft polyamide substrate, and etching the copper substrate .   The method according to claim 1, wherein a dry film process is performed before the plating.   The method according to claim 1, wherein the entire copper substrate is etched. The method according to claim 1 or 2, wherein a portion of the copper substrate is etched.

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