JPH0774280A - Flexible circuit board having bump and production thereof - Google Patents

Abstract

PURPOSE:To provide a flexible circuit board, and production method thereof, having a circuit wiring pattern narrower than the diameter of a conduction hole for forming a bump in which bumps having uniform profile can be formed stably. CONSTITUTION:The flexible circuit board comprises a flexible insulating base member 1 having one side formed with a circuit wiring pattern 8 and the other side provided with bumps 7 each having one end being jointed electrically, on the other side of the base member 1, with the circuit wiring pattern 8 through the insulating base member 1 at a position corresponding to the wiring pattern 8 and the other end projecting outward from the base member 1, wherein the width of the wiring pattern 8 is set shorter than the diameter of a conduction hole 6 for the bump 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a required circuit wiring pattern on a flexible insulating base material.
The present invention relates to a flexible circuit board having a bump for a circuit component which is electrically joined to a substrate and which protrudes to the outside through the insulating base material and a method for manufacturing the flexible circuit board.

[0002]

2. Description of the Related Art As a flexible circuit board of this type having a so-called bump, such as a terminal for mounting a circuit component such as an IC or a terminal for inspecting a circuit component,
As shown in FIG. 4, a required circuit wiring pattern 22 is provided on one surface of the flexible insulating base material 21, and the circuit wiring pattern 22 on the other surface of the insulating base material 21 is provided. One end of the circuit part which penetrates the insulating base material 21 from the corresponding position and is electrically connected to the circuit wiring pattern 22 and the other end of which protrudes to the outside of the insulating base material 21. For example, some bumps 27 are provided for the purpose. Here, the circuit wiring pattern 22 has holes 26 for forming bumps.
It is formed wider than.

FIG. 5 is a manufacturing process drawing of a flexible circuit board having such bumps. First, as shown in FIG. 1A, a flexible or hard insulating base material 21 is formed. A required circuit wiring pattern 22 is formed on one surface and an insulation board is formed.
A metal mask 23 is formed on the other surface of the metal material 21.

This metal mask 23 is a circuit wiring pattern.
The hole 24 is formed in a corresponding portion where the hole 22 is located. A surface protection layer 25 is formed on the surface of the circuit wiring pattern 22 by printing or curing with polyimide varnish or the like.
To form. The surface protection layer 25 may be formed by bonding a flexible insulating film such as polyimide with an adhesive.

Next, as shown in FIG. 2B, the metal mask 2
An excimer laser light A is irradiated from the side of 3 to form a conducting hole 26 in the insulating base material 21 which reaches the circuit wiring pattern 22.

Next, after removing the unnecessary metal mask 23 by means of etching or the like as shown in FIG. 3C, one end of the circuit wiring is connected to the conduction hole 26 as shown in FIG. A bump 27 for electrically connecting to the pattern 22 and having the other end protruding from the insulating base material 21 to the outside for connecting a circuit component such as an IC is formed by plating with a conductive metal. To fill and form.

According to such a method, the bump holes 26 are formed.
Even if an attempt is made to improve the bump arrangement density by making the circuit wiring pattern 22 of the forming portion of the bump smaller than the diameter of the bump hole 26, when the bump 27 is formed by plating, the plating pattern is for conduction. Since only a part of the bottom of the hole 26 exists, it is not possible to form a bump having a uniform shape.

Further, in the case of the above method, since the circuit wiring pattern 22 located in the bump forming portion must be formed wider than the bump diameter, the fine circuit wiring pattern is required.
However, there is a problem that the substrate forming capability cannot be fully exerted, and a substrate for high-density mounting cannot be provided.

[0009]

The present invention has a circuit wiring pattern having a width narrower than the diameter of a conduction hole for forming a bump and stably forming a bump having a uniform shape. The present invention provides a flexible circuit board having bumps that can be manufactured and a method for manufacturing the same.

Therefore, according to the present invention, the required circuit wiring pattern is provided on one surface of the flexible insulating base material, and the circuit wiring pattern on the other surface of the insulating base material is provided. For the connection of circuit parts that penetrates the insulating base material from the corresponding portion located at the position of 1 to electrically connect one end to the circuit wiring pattern and the other end protrudes to the outside of the insulating base material. In the flexible circuit board having the bumps, the width of the circuit wiring pattern electrically connected to the bumps for connecting the circuit components is smaller than the diameter of the conduction hole for the bumps. Provided is a flexible circuit board having bumps formed thereon.

As a manufacturing method therefor, a conductor layer for forming a circuit wiring pattern is provided on one surface of the flexible insulating base material, and a required surface is formed on the conductor layer. An etching resist pattern for forming the circuit wiring pattern is formed, and a metal mask is formed on the other surface of the flexible insulating base material, and the circuit wiring pattern is formed on the metal mask. A hole having a diameter larger than that of the circuit wiring pattern is formed in a corresponding portion where a resist pattern for forming a pattern is located, and then an excimer laser beam is irradiated from the metal mask side to form the above-mentioned hole. A conductive hole is formed from the hole portion to reach the conductor layer for forming the circuit wiring pattern, then the metal mask layer is peeled off, and one end of the conductive hole is electrically connected to the conductive layer. And the other end is the above-mentioned insulating base. After forming bumps for connecting circuit components protruding to the outside, the conductor layer is etched to form a circuit wiring pattern, then the resist layer is removed, and then the circuit wiring pattern is removed. Each step of forming a surface protective layer on the surface can be adopted.

The surface protective layer may be formed by bonding a flexible insulating film such as polyimide with an adhesive. In this case, the bump forming process is performed in multiple steps. That is, a step of first forming the bump height so as not to project from the insulating base material, then forming the surface protective layer, and then performing bump plating again to secure a desired bump height is taken.

Further, in the above step, after the step of peeling off the metal mask layer, the conductive layer which is not corroded by the chemical used in the step of forming the circuit wiring pattern with respect to the conductor layer at the bottom of the conduction hole is used. A manufacturing method including a step of forming a conductive metal layer can also be adopted. According to this method, the circuit wiring pattern
Since there is no risk of the bottom of the bump being protected by the conductive metal layer and being etched during the etching forming step of
Bump strength and reliability can be achieved at a high level.

[0014]

The present invention will be described in more detail below with reference to the illustrated embodiments. FIG. 1 is a sectional view conceptually showing an essential part of a flexible circuit board having bumps according to an embodiment of the present invention. A required circuit wiring pattern 8 is provided, and the insulating base material 1 is penetrated from the corresponding portion of the other side of the insulating base material 1 where the circuit wiring pattern 8 is located. One end is electrically connected to the circuit wiring pattern 8 and the other end is provided with a bump 7 for connecting a circuit component projecting to the outside of the insulating base material 1.

The width of the circuit wiring pattern 8 is smaller than the diameter of the conduction hole 6 for the bump 7.

FIGS. 2 (1) to 2 (5) show manufacturing process diagrams for that purpose. First, as shown in FIG. 1 (1), for example, one having an adhesive or a non-adhesive double-sided flexible type. A material such as a conductive copper clad laminate is prepared, and an etching resist pattern 3 for forming a circuit wiring pattern is formed on the copper foil layer 2 on one surface of the insulating base material 1. Further, the copper foil on the other surface of the insulating base material 1 is etched to form the metal mask 4.

The metal mask 4 has a circuit wiring pattern.
The hole 5 is formed in the corresponding portion where the resist pattern 3 for forming the pattern is located. The width of the resist pattern 3 for forming the circuit wiring pattern is formed to be smaller than the diameter of the hole 5.

Next, as shown in FIG. 2B, excimer laser light A is irradiated from the side of the metal mask 4 to form a conduction hole 6 reaching the copper foil layer 2 from the hole 5. Therefore,
As shown in FIG. 3C, the metal mask 4 is removed by etching.

Then, as shown in FIG. 4 (4), the conduction hole 6 is formed.
On the other hand, one end is electrically joined to the copper foil layer 2 by a plating process of a good conductive metal or a filling process with solder or the like, and the other end is projected to the outside of the insulating base material 1 for connecting circuit components. The bump 7 is formed.

Further, as shown in FIG. 5 (5), after the copper foil layer 2 is etched to form a desired circuit wiring pattern 8, the unnecessary resist pattern 3 is removed, and finally the circuit wiring is formed. The surface protective layer 9 is formed on the surface of the pattern 8 by printing or curing a polyimide varnish. As a result, it is possible to manufacture a flexible circuit board having bumps in which the width of the circuit wiring pattern 8 is narrower than the diameter of the conduction hole 6 for the bump 7.

Here, the surface protective layer 9 can be formed by bonding a flexible insulating film such as polyimide with an adhesive, and in this case, the bump forming step is performed in plural times. That is, a step of first forming a bump height so as not to project from the insulating base material 1 and then forming the surface protection layer 9 and then performing bump plating again to secure a desired height of the bump 7. Is adopted.

3 (1) to 3 (4) are other manufacturing process diagrams capable of achieving bump strength and reliability at a high level. Similar to the above process, as shown in FIG. 3 (1), the metal mask 4 is formed. After the excimer laser light A is irradiated from the side to form the conduction hole 6 reaching the copper foil layer 2 for forming the circuit wiring pattern from the portion of the hole 5, the metal mask 4 is peeled off.

Therefore, as shown in FIG. 2B, the conduction hole 6 is formed.
A conductive metal layer 10 of gold or the like, which is not corroded by chemicals when forming a circuit wiring pattern in a later step, is formed on the copper foil layer 2 exposed at the bottom of the.

Similar to the steps of the above embodiment, the bump 7 forming step, the circuit wiring pattern 8 forming step, the resist pattern 3 removing step and the surface are performed as shown in FIGS. By sequentially performing the step of forming the protective layer 9, the width of the circuit wiring pattern 8 is made narrower than the diameter of the conduction hole 6 for the bump 7, and the bump strength and reliability are achieved at a high level. A flexible circuit board having bumps can be manufactured.

In the above embodiment, steps such as a resist pattern for forming a circuit wiring pattern and a masking process for protecting the copper foil layer and the like can be optionally carried out if necessary.

[0026]

According to the flexible circuit board having bumps and the method of manufacturing the same according to the present invention, a conductive hole for forming a bump is formed, and after forming the bump, a circuit wiring pattern is formed. Therefore, even if the width of the circuit wiring pattern is narrower than the diameter of the conduction hole for the bump, it is possible to stably provide the flexible circuit board having the high-precision bump, and to arrange the bump. The pitch can be reduced to form bumps with high density.

After the step of removing the metal mask layer, a step of forming a conductive metal layer which is not corroded by the chemical used in the step of forming the circuit wiring pattern on the conductor layer at the bottom of the conduction hole. In addition, since there is no possibility that the bottom of the bump is protected by the conductive metal layer and etched during the step of etching the circuit wiring pattern, the bump strength and reliability can be achieved at a high level.

[Brief description of drawings]

FIG. 1 is a sectional configuration view conceptually showing a main part of a flexible circuit board provided with bumps according to an embodiment of the present invention.

2 (1) to (5) are manufacturing process diagrams thereof.

3A to 3D are manufacturing process diagrams according to another embodiment of the present invention.

FIG. 4 is a sectional configuration view conceptually showing a main part of a conventional flexible circuit board provided with bumps.

5 (1) to (4) are manufacturing process diagrams thereof.

[Explanation of symbols]

 1 Flexible Insulating Base Material 2 Copper Foil Layer 3 Resist Pattern 4 Metal Mask 5 Hole 6 Conduction Hole 7 Bump 8 Circuit Wiring Pattern 9 Surface Protection Layer 10 Conductive Metal Layer

Claims (3)

[Claims] 1. A flexible insulating base material is provided with a required circuit wiring pattern on one surface thereof, and the corresponding portion where the circuit wiring pattern is located on the other surface of the insulating base material. Through the insulating base material, one end of which is electrically joined to the circuit wiring pattern and the other end of which is provided with a bump for connecting a circuit component protruding outside the insulating base material. In the flexible circuit board, the width of the circuit wiring pattern electrically connected to the bumps for connecting the circuit components is formed to be smaller than the diameter of the conducting hole for the bumps. A flexible circuit board having bumps. 2. A flexible insulating base material has a conductor layer for forming a circuit wiring pattern on one surface thereof, and a required circuit wiring pattern is formed on the surface of the conductor layer. Etching resist pattern for forming a metal mask is formed on the other surface of the flexible insulating base material, and a resist pattern for forming the circuit wiring pattern is formed on the metal mask. A hole having a diameter larger than that of the circuit wiring pattern is formed in a corresponding portion where the burner is located, and then excimer laser light is irradiated from the metal mask side to form the circuit wiring pattern from the hole portion. A conductive hole for forming a conductive layer is formed, then the metal mask layer is peeled off, one end of the conductive hole is electrically joined to the conductive layer and the other end is Connection of circuit parts protruding outside the insulating base material After forming the bumps for forming the bumps, the conductor layer is etched to form a circuit wiring pattern, the resist layer is then removed, and then a surface protective layer is formed on the surface of the circuit wiring pattern. A method for manufacturing a flexible circuit board having bumps including steps. 3. After the step of peeling off the metal mask layer, a conductive metal layer which is not corroded by the chemical used in the step of forming the circuit wiring pattern is formed on the conductor layer at the bottom of the conduction hole. The method for manufacturing a flexible circuit board having bumps according to claim 2, wherein the step of adding is added.