JP3224056B2 - Flexible circuit board with bumps and method of manufacturing the same - Google Patents

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 provided with bumps for circuit components which are electrically connected to a component and project outside through the insulating base material, and a method of manufacturing the same.

[0002]

2. Description of the Related Art This type of flexible circuit board 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, includes:
As shown in FIG. 4, a required circuit wiring pattern 22 is provided on one surface of a 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 a circuit component that penetrates through the insulating base material 21 from the corresponding portion and electrically connects one end to the circuit wiring pattern 22 and the other end protrudes outside the insulating base material 21. There is a configuration in which a bump 27 is provided. Here, the circuit wiring pattern 22 is formed with holes 26 for forming bumps.
It is formed wider than that.

FIG. 5 shows a manufacturing process of a flexible circuit board provided with 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 side and an insulating base is formed.
A metal mask 23 is formed on the other surface of the metal material 21.

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

[0005] Next, as shown in FIG.
A conductive hole 26 reaching the circuit wiring pattern 22 by irradiating excimer laser light A from the side 3 is formed in the insulating base material 21.

Next, as shown in FIG. 3 (3), after the unnecessary metal mask 23 is removed by means such as etching, one end of a circuit wiring is connected to the conduction hole 26 as shown in FIG. 4 (4). A bump 27 for connecting a circuit component such as an IC having a shape electrically connected to the pattern 22 and having the other end protruding from the insulating base material 21 to the outside is formed by plating a conductive metal or the like. To form a filling process.

According to such a method, the bump holes 26 are formed.
In order to improve the bump arrangement density by forming the circuit wiring pattern 22 having a smaller diameter than the diameter of the bump hole 26, when forming the bump 27 by plating, the plating pattern becomes conductive. Since it exists only at a part of the bottom of the hole 26, a bump having a uniform shape cannot be formed.

Further, in the case of the above method, since the circuit wiring pattern 22 located at the bump forming portion must be formed wider than the bump diameter, the fine circuit wiring pattern 22 must be formed.
However, there is a problem that the ability to form a component cannot be sufficiently exhibited, and a substrate corresponding to high-density mounting cannot be provided.

[0009]

SUMMARY OF THE INVENTION The present invention is to provide a circuit wiring pattern having a width smaller than the diameter of a conductive hole for forming a bump, and to stably form a bump having a uniform shape. The present invention provides a flexible circuit board provided with a bump that can be formed and a method for manufacturing the same.

Therefore, in the present invention, a required circuit wiring pattern is provided on one surface of a flexible insulating base material, and the circuit wiring pattern is provided on the other surface of the insulating base material. Is connected to the circuit wiring pattern at one end through the insulating base material from the corresponding portion located at the position indicated by, and the other end projects to the outside of the insulating base material for connection of circuit parts. 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 conductive hole for the bumps. And the circuit wiring pattern is formed on the bottom of the bump.
Conductive gold that is not corroded by the chemicals used to form
Provided is a flexible circuit board provided with a bump , comprising a metal layer .

As a manufacturing method therefor, a conductor layer for forming a circuit wiring pattern is provided on one surface of a flexible insulating base material, and the surface of the conductor layer has a required surface. 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. 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 excimer laser light is irradiated from the metal mask side to form the hole. A conduction hole reaching the conductor layer for forming the circuit wiring pattern from the hole portion is formed, and then the metal mask layer is peeled off, and one end of the conduction hole is electrically connected to the conductor layer. And the other end is insulated 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 can be formed by bonding a flexible insulating film such as polyimide with an adhesive. In this case, the bump forming step is performed in a plurality of times. That is, first, the bump height is formed so as not to protrude from the insulating base material, then, after forming the above-mentioned surface protective layer, bump plating is performed again to secure a desired bump height.

In the above step, after the step of removing the metal mask layer, the conductive layer at the bottom of the conductive hole is not corroded by the chemical used in the step of forming the circuit wiring pattern. A manufacturing method in which a step of forming a conductive metal layer is added can also be adopted. According to this method, the circuit wiring pattern
Since there is no possibility that the bottom of the bump is protected by the conductive metal layer and is etched during the step of forming
Bump strength and reliability can be achieved at a high level.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in further detail with reference to the illustrated embodiments. FIG. 1 is a sectional view schematically showing a main part of a flexible circuit board provided with bumps according to one embodiment of the present invention. A required circuit wiring pattern 8 is provided, and the insulating base material 1 is penetrated through the insulating base material 1 from a corresponding portion of the other surface 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 circuit components protruding outside the insulating base material 1.

Here, the width of the circuit wiring pattern 8 is formed smaller than the diameter of the conductive hole 6 for the bump 7.

FIGS. 2 (1) to 2 (5) show manufacturing process diagrams for this purpose. First, as shown in FIG. 2 (1), for example, a double-sided flexible type having an adhesive or a non-adhesive type is used. 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 a copper foil layer 2 on one surface of an insulating base material 1. Further, a metal mask 4 is formed by etching the copper foil on the other surface of the insulating base material 1.

The metal mask 4 has a circuit wiring pattern
A hole 5 is formed in a corresponding portion where a resist pattern 3 for forming a 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, an excimer laser beam 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 site. Therefore,
The metal mask 4 is removed by etching as shown in FIG.

Next, as shown in FIG.
One end is electrically connected to the copper foil layer 2 by plating with a good conductive metal or filled with solder or the like, and the other end is connected to a circuit component projecting outside the insulating base material 1. The bump 7 is formed.

Further, as shown in FIG. 5 (5), after the copper foil layer 2 is etched to form a required 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. This makes it possible to manufacture a flexible circuit board having a bump in which the width of the circuit wiring pattern 8 is smaller 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 the bump height so as not to protrude from the insulating base material 1 and then forming the above-mentioned surface protection layer 9 and then performing bump plating again to secure a desired height of the bump 7. Is adopted.

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

Therefore, as shown in FIG.
A conductive metal layer 10 made of gold or the like which is not corroded by a chemical used for forming a circuit wiring pattern in a later process is formed on the copper foil layer 2 exposed at the bottom of the substrate.

In the same manner as in the steps of the above-described embodiment, as shown in FIGS. 3 (3) and (4), a step of forming a bump 7, a step of forming a circuit wiring pattern 8, a step of removing a resist pattern 3, and a surface. By sequentially forming the protective layer 9, the width of the circuit wiring pattern 8 is configured to be smaller than the diameter of the conductive 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 masking for protecting a resist pattern and a copper foil layer for forming a circuit wiring pattern can be arbitrarily performed as required.

[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 formed to be smaller than the diameter of the conductive hole for the bump, a flexible circuit board having high-precision bumps can be stably provided, and the arrangement of the bumps can be provided. Bumps can be formed at a high density by reducing the pitch.

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 a circuit wiring pattern on the conductive layer at the bottom of the conduction hole. Is added, there is no possibility that the bottom of the bump is protected by the conductive metal layer and etched during the step of forming the circuit wiring pattern, so that the bump strength and reliability can be achieved at a high level.

[Brief description of the drawings]

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

FIGS. 2A to 2C are manufacturing process diagrams.

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

FIG. 4 is a cross-sectional configuration diagram conceptually showing a main part of a flexible circuit board provided with a conventional bump.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible insulating base material 2 Copper foil layer 3 Resist pattern 4 Metal mask 5 Hole 6 Conducting hole 7 Bump 8 Circuit wiring pattern 9 Surface protection layer 10 Conductive metal layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/12 H05K 1/03 H05K 1/11

Claims (3)

(57) [Claims] A circuit wiring pattern is provided on one side of a flexible insulating base material, and a corresponding portion of the other surface of the insulating base material where the circuit wiring pattern is located. One end is electrically connected to the circuit wiring pattern through one end of the insulating base material and the other end is provided with a bump for connecting circuit parts protruding outside the insulating base material. In the flexible circuit board, a width of a circuit wiring pattern electrically connected to the bump for connecting the circuit component is formed to be smaller than a diameter of a conduction hole for the bump , and Van
Used at the bottom of the loop when forming the above circuit wiring pattern
A flexible circuit board provided with a bump, comprising a conductive metal layer that is not corroded by chemicals . 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. And a metal mask is formed on the other surface of the flexible insulating base material. The metal mask has a resist pattern for forming the circuit wiring pattern. A hole having a diameter larger than that of the circuit wiring pattern is formed in a corresponding portion where the pattern is located, and then excimer laser light is irradiated from the metal mask side to start the circuit wiring pattern from the hole. Forming a conduction hole reaching the conductor layer for forming a contact hole, then peeling the metal mask layer, one end of the conduction hole is electrically connected to the conductor layer, and the other end of the conduction hole is connected to the conductor layer. Connection of circuit parts protruding outside the insulating base material After the formation of the bumps, the conductor layer is etched to form a circuit wiring pattern, the resist layer is removed, and then a surface protective layer is formed on the surface of the circuit wiring pattern. A method of manufacturing a flexible circuit board provided with a bump including each step. 3. A conductive metal layer which is not corroded by a chemical used in a circuit wiring pattern forming step is formed on the conductive layer at the bottom of the conductive hole after the step of removing the metal mask layer. 3. The method of manufacturing a flexible circuit board provided with bumps according to claim 2, further comprising the step of: