JP2001284794A - Method for manufacturing flexible printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing flexible printed wiring boards by which a high-density circuit design can be realized by an accurate processing. SOLUTION: According to the method for manufacturing flexible printed wiring boards for HDDs, openings are formed in connection parts of a single- sided flexible printed wiring board on which a specified circuit is formed in such a way that the diameter of the openings is larger than those in connection parts between circuits on the surface for connecting another single-sided flexible printed wiring board on which specified circuits is connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible wiring board for an HDD, which can be manufactured at a low cost without requiring complicated and precise processes for high-density circuit design and which can improve the yield at the time of connection. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a double-sided flexible printed wiring board for HDD, as shown in FIG. 2, a through-hole is drilled through a double-sided copper foil plate in which copper foil is bonded to both sides of an insulating base material with an adhesive. After drilling holes, the front and back copper foil and the inner wall of the drilled through holes are plated with copper to make front and back conductive connections, and after forming a predetermined circuit by etching, insulation of polyimide resin film etc. A method has been adopted in which a circuit is covered with a coverlay film in which an adhesive is applied to a base material, and a reinforcing film such as a polyimide resin is bonded with an adhesive for reinforcement during product assembly. However, in these processing methods, using a double-sided copper foil plate in which copper foil is bonded to both sides of an insulating base material such as a polyimide resin film with an adhesive,
A large number of processes such as copper plating and bonding of a reinforcing plate are required, which complicates the manufacturing process and causes a problem such as a reduction in product yield, and an increase in material cost is an obstacle to a reduction in product cost.

[0003]

SUMMARY OF THE INVENTION The present invention provides a high-density H
When manufacturing a flexible printed wiring board for DD, the problem that occurs when manufacturing a double-sided flexible printed wiring board is solved by bonding a single-sided flexible printed wiring board and connecting the front and back using a solder paste. It is an object of the present invention to provide a method for manufacturing a high-density flexible printed wiring board without requiring complicated processing steps.

[0004]

According to the present invention, a connecting portion of a single-sided flexible printed wiring board on which a predetermined circuit is formed is provided.
Provide an opening diameter larger than the connection opening between the surface circuits,
A flexible wiring board for HDD, wherein another single-sided flexible printed wiring board on which a predetermined circuit is formed is connected, and further, a solder plating process is performed on a connection portion to stabilize wettability of a solder paste used for conductive connection. Manufacturing method.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The material of the flexible printed wiring board having a circuit formed on one side used in the present invention is a material obtained by integrally molding a copper foil on one side of a flexible insulating base material such as a polyimide resin film by heating and pressing. This is the same as that used for flexible printed wiring boards. The same adhesive is used for the coverlay film and the adhesive in which the adhesive is applied to the insulating substrate covering the insulating substrate surface having the circuit. The method for manufacturing the flexible wiring board for HDD of the present invention will be described below. The flexible wiring board used in the present invention is obtained by forming a predetermined circuit by etching on a single-sided copper foil plate having a copper foil on one side of an insulating base, and then forming a coverlay film having an opening of 1.0 to 4.0 mm in diameter. The circuit surface is coated, and a solder plating process is performed on the connection portion where the coverlay film is opened. The thickness of the solder plating is about 1 to 20 μm, and there is no particular restriction on the thickness.

[0006] A connection hole having a diameter of 1.0 to 3.0 mm is opened in the solder-plated connection portion by a process such as punching. Form a predetermined circuit on another single-sided flexible printed wiring board for bonding using the same material,
After covering with a coverlay film having a diameter of 1.0 to 2.0 mm larger than the surface connection portion, solder plating is performed. An adhesive is used when bonding each of the prepared flexible printed wiring boards, but the opening diameter is about 1.0 to 2.0 mm more than the connection hole opened in the flexible printed wiring board for bonding. By using a large opening, it is possible to prevent the bonding displacement of the adhesive and the exudation of the adhesive at the time of thermocompression bonding from adhering to the connection portion. After bonding the single-sided flexible printed wiring boards to a predetermined position using an adhesive, in order to secure the connection between each layer, when mounting various connectors and chip components on the flexible printed wiring board, Also, the solder paste is filled by printing or the like, a reflow process is performed, and the solder paste is melted, thereby making a conductive connection between the respective layers.

In the present invention, the structure of a double-sided flexible printed wiring board is formed by forming a single-sided flexible printed wiring board into a predetermined shape and then bonding them together. In addition, a flexible printed wiring board can be manufactured in a simplified process that does not require a complicated process. The important point of the present invention is that the opening portion of the single-sided flexible printed wiring board to be bonded and connected and the adhesive portion to be used are larger than the opening diameter opened for connection, so that the displacement at the time of bonding and Stable connection reliability can be ensured by bonding in a shape that is not affected by the exudation of the adhesive and by performing a solder plating process in advance on the surface of the connection portion that is to be electrically connected with a solder paste or the like.

Hereinafter, the present invention will be described with reference to the drawings. 1A to 1E are schematic cross-sectional views of a connection portion of a flexible printed wiring board having a circuit on one side. FIG. 1 (A)
Is a copper foil plate material obtained by integrally forming a copper foil 2 on an insulating base material 1. The upper diagram of FIG. 1B shows a state where a predetermined circuit is formed by etching. The figure below shows another single-sided plate for bonding. The steps in FIGS. 1A and 1B are the same as those in the related art, and are not particularly limited. The upper view of FIG. 1C shows a state in which after the circuit is formed, the circuit is covered with the cover lay film 3 and the connection portion is subjected to solder plating.
The lower part of FIG. 1 (C) is another one-sided flexible printed wiring board for lamination processed in the same manner as the upper part. FIG.
(D), a connection hole is drilled in the solder-plated connection portion of the surface circuit portion, and a single-sided flexible printed wiring board similarly subjected to solder plating for connection is placed in a predetermined position with an adhesive 5. Shows the state of being attached. FIG. 1E shows a state in which the opening is filled with the solder paste 6 and conductively connected to a connection portion of another wiring board.

[0009]

According to the present invention, a method for manufacturing a flexible wiring board for an HDD, which enables a high-density circuit design to be manufactured at a low cost without requiring complicated and accurate processes and to improve the yield at the time of connection. It is.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a connection portion of a flexible printed wiring board according to the present invention.

FIG. 2 is a schematic cross-sectional view of a connection portion of a conventional flexible printed wiring board.

Claims (2)

[Claims] 1. A single-sided flexible printed wiring board in which a predetermined circuit is formed by providing a larger opening diameter at a connection portion of a single-sided flexible printed wiring board on which a predetermined circuit is formed than a connection portion opening between surface circuits. And a method of manufacturing a flexible printed wiring board for HDD. 2. A single-sided flexible printed wiring board on which a predetermined circuit is formed by providing a larger opening diameter at a connection portion of a single-sided flexible printed wiring board on which a predetermined circuit is formed than a connection portion opening between surface circuits. A method of manufacturing a flexible printed wiring board for HDD, wherein a solder plating process is performed on a surface of a connecting portion when connecting the flexible printed wiring boards, and a conductive connection between the flexible printed wiring boards is made with a solder paste.