Method for repairing metal finish layer on surface of electrical connection pad of circuit board

Abstract

A method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board is provided. Firstly, a circuit board having a plurality of electrical connection pads on a surface thereof is provided, and a plurality of metal finish layers are formed on surfaces of the electrical connection pads, wherein some of the metal finish layers have at least a fault. Then, a micro deposition process is performed on the metal finish layer having the fault using micro droplets. Therefore, a production yield can be improved and a fabrication cost can be reduced as a result.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein:

FIG. 1A to FIG. 1C are schematic diagrams showing a method for forming a nickel/gold metal finish layer on a surface of an electrical connection pad of a circuit board according to prior-art; and

FIG. 2A and FIG. 2B are flow charts showing a method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention is described in the following with specific embodiments, so that one skilled in the pertinent art can easily understand other advantages and effects of the present invention from the disclosure of the invention.

FIG. 2A and FIG. 2B are flow charts showing a method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board.

Referring to FIG. 2A, firstly, a circuit board 2 having a plurality of electrical connection pads 20 on at least a surface thereof is provided. The electrical connection pads 20, 20′ and 20″ can be a wire bonding pad, a bump pad, a surface mount technology (SMT) pad or a solder ball pad. Then, a solder mask 21 is formed on the surface of the circuit board 2. The solder mask 21 is formed with a plurality of openings 210 to expose the electrical connection pads 20, 20′ and 20″ from the surface of the circuit board 2. Further, a metal finish layer 22 is formed on the electrical connection pad 20, wherein the metal finish layer 22 has a fault. For example, an incomplete metal finish layer 22 is formed on the surface of the electrical connection pad 20′ at a position a on the circuit board 2, or no metal finish layer is formed on the surface of the electrical connection pad 20″ at a position b on the circuit board 2.

Referring to FIG. 2B, a metal layer is formed by a micro deposition process using a micro droplet 3 on the surfaces of the electrical connection pads 20′ and 20″ at the position a and the position b on the circuit board 2. Thus, a metal finish layer 22 is formed on the surfaces of the electrical connection pads 20′ and 20″ to repair the fault, so as to improve a production yield and reduce a fabrication cost. Furthermore, the foregoing metal finish layer is made of a material selected from the group consisting of gold, nickel, palladium, silver, tin, nickel/palladium, chromium/titanium, nickel/gold, palladium/gold and nickel/palladium/gold.

If the foregoing metal finish layer 22 is a single-layered metal, the micro deposition process is performed once using the micro droplet 3. However, if it is a double-layered or multi-layered metal, the micro deposition process is performed twice using the micro droplet 3. Therefore, the metal finish layer 22 having a double-layered metal can be formed on the surface of the electrical connection pad 20. Alternatively, the metal finish layer 22 having a multi-layered metal can also be formed.

In the present embodiment, a metal layer is formed by a micro deposition process using a micro droplet during or after the fabrication of the circuit board (i.e. the treatment of the surface of the circuit board), so as to repair the fault of the metal finish layer.

Accordingly, referring to the method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board proposed in the present invention, a micro deposition process is performed using a micro droplet to repair the metal finish layer having a fault. Therefore, the method proposed in the present invention is able to effectively repair the metal finish layer having the fault once the fault has been detected, so as to dramatically improve a production yield and reduce a fabrication cost.

The invention has been described using exemplary preferred embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements; for example, the number and locations of resistors and capacitors can be flexibly arranged according to practical requirements. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board, comprising steps of: providing a circuit board having a plurality of electrical connection pads on at least a surface thereof, surfaces of the electrical connection pads being formed with a plurality of metal finish layers, wherein some of the metal finish layers have at least a fault; andperforming a micro droplet process to repair the metal finish layer having the fault on the surface of the electrical connection pad.

2. The method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board of claim 1, wherein the fault is a non-formed metal finish layer or an incomplete metal finish layer.

3. The method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board of claim 1, wherein the metal finish layer is made of a material selected from the group consisting of gold, nickel, palladium, silver, tin, nickel/palladium, chromium/titanium, nickel/gold, palladium/gold and nickel/palladium/gold.

4. The method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board of claim 1, wherein the method further comprises a step of forming a solder mask on the surface of the circuit board before forming the metal finish layer on the surface of the circuit board, and the solder mask comprises a plurality of openings to expose the electrical connection pads.

5. The method for repairing a metal finish layer on a surface of an electrical connection pad of a circuit board of claim 1, wherein the electrical connection pad is selected from the group consisting of a wire bonding pad, a bump pad, a surface mount technology (SMT) pad and a ball pad.