Substrate with surface finished structure and method for making the same

Abstract

A substrate with surface finished structure and a method for manufacturing the same are disclosed. The method comprises: forming a circuit layer and a solder mask on the surface of the substrate in sequence, wherein a plurality of openings are formed in the solder mask to expose the portion of the circuit layer to be electrical contact pads which having at least a wire bonding pad and a plurality of solder pads; and forming a Ni/Au layer on the surface of the wire bonding pad and a chemical gold layer on the surface of the solder pads. Therefore, the disclosed structure can prevent the electrical contact pads from oxidation for a long time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1C are cross-sections of a prior art method for manufacturing the substrate with surface finished structure;

FIG. 2A to 2B are cross-sections of a method for manufacturing the substrate with surface finished structure of a preferred embodiment of the present invention; and

FIG. 3A to 3D are cross-sections of a method for manufacturing the substrate with surface finished structure of another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 2A to 2B, which are schematic cross-section illustrations of the substrate with surface finished structure of a preferred embodiment of the present invention. First, as shown in FIG. 2A, a substrate 20 is provided, which can be a single-layer or a multi-layer finished the preceding process circuit board. Besides, a seed layer 21, a circuit layer 22, and a solder mask 23 for isolation and protection are formed on the upper and lower surface of the substrate 20, and a plurality of openings are formed in the solder mask 23 by exposure and development to expose the portion of the circuit layer 22 therebeneath to be electrical contact pads 24, wherein the electrical contact pads 24 comprise at least a wire bonding pad 24b and solder pads 24a (step A). Then, a Ni/Au layer 25 is formed on the surface of the wire bonding pad 24b (a Ni layer is formed first, and then an Au layer is covered thereon) (step B).

After that, as shown in FIG. 2B, a chemical gold layer 27 is coated on the surface of the solder pads 24a and the Ni/Au layer 25 on the wire bonding pad 24b by chemical deposition (step C).

Thus, the substrate 20 with surface finished structure made of the example, the surface of the solder pads 24a and the Ni/Au layer 25 on the wire bonding pad 24b have a chemical gold layer 27. The solder pads 24a will not be oxidized for a long time by the protection of the chemical gold layer 27.

Then, referring to FIGS. 3A to 3D, which are schematic cross-section illustrations of the substrate with surface finished structure of a second preferred embodiment of the present invention. The step (A) of the second example and the step (A) of the first example are the same. First, as shown in FIG. 3A, a substrate 30 is provided, which can be a single-layer or a multi-layer finished the preceding process circuit board. Besides, a seed layer 31, a circuit layer 32, and a solder mask 33 are formed on the upper and lower surface of the substrate 30, and a plurality of openings are formed in the solder mask 33 to expose the portion of the circuit layer 32 therebeneath to be electrical contact pads 34, wherein the electrical contact pads 34 comprise at least a wire bonding pad 34b and solder pads 34a (step A). Then, a Ni/Au layer 35 is formed on the surface of the wire bonding pad 34b (a Ni layer is formed first, and then an Au layer is covered thereon) (step B).

Then, as shown FIG. 3B, a resist layer 36 of photosensitive polymer material is formed on the openings and the surface of the solder mask 33, and a plurality of the resist layer openings are formed in the resist layer 36 by exposure and development to expose the surface of the solder pads 34a therebeneath (step B1). Then, as shown FIG. 3C, a chemical gold layer 38 is coated on the surface of the solder pads 34a by chemical deposition (step C). Finally, as shown in FIG. 3D, the resist layer 36 is removed to expose the Ni/Au layer 35 on the wire bonding pad 34b and the solder mask 35 therebeneath (step C1).

The difference between the substrate 30 with surface finished structure of the second example and the first example is the chemical gold layer 38 only formed on the surface of the solder pads 34a in the second example, however, the chemical gold layer 27 is formed on the surface of the solder pads 24a and the Ni/Au layer 25 on the wire bonding pad 24b at the same time in the first example. The surface of the solder pads 34a of the second example are protected by the chemical gold layer 38, and also have the effectiveness as the first example. That is, the surface of the solder pads 34a of the second example does not oxidation easily for a long time.

Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.

Claims

1. A substrate with surface finished process structure, comprising: a substrate having a circuit layer, solder mask, and a plurality of openings, wherein the solder mask is formed on the surface of the substrate in sequence, the openings are formed in the solder mask to expose the portion of the circuit layer therebeneath to be electrical contact pads, and the electrical pads have at least a wire bonding pad and solder bumping pads;a Ni/Au layer formed on the surface of the at least one wire bonding pad; and a chemical gold layer formed on the surface of the solder bumping pads.

2. The structure as claimed in claim 1, wherein the chemical gold layer is formed on the surface of the Ni/Au layer.

3. The structure as claimed in claim 1, wherein the substrate is either single-layer circuit board or multi-layer circuit board.

4. The structure as claimed in claim 1, wherein solder mask is either green paints or black paints.

5. A method for manufacturing a substrate with surface process finished structure, comprising the following steps: (A) providing a substrate having a circuit layer, a solder mask, and a plurality of openings, wherein the solder mask is formed on the surface of the substrate, the openings are formed in the solder mask to expose the portion of the circuit layer therebeneath to be electrical contact pads, andthe electrical pads have at least a wire bonding pad and solder bumping pads;(B) forming a Ni/Au layer on the surface of the at least one wire bonding pad; and(C) forming a chemical gold layer in the openings.

6. The method as claimed in claim 5, further comprising a step of (B1): forming a resist layer on the openings and the surface of the solder mask, and forming a plurality of resist layer openings in the resist layer to expose the surface of the solder bumping pads therebeneath, wherein the step of (B1) is performed after the step of (B) and before the step of (c).

7. The method as claimed in claim 6, further comprising a step of (C1): removing the resist layer, wherein the step of (C1) is performed after the step of (c).

8. The method as claimed in claim 5, wherein the solder mask of the step (A) is either green paints, or black paints.

9. The method as claimed in claim 5, wherein the chemical gold layer in step (c) is formed by sputtering, vapor deposition, physical deposition, or chemical deposition.

10. The method as claimed in claim 6, wherein the resist layer in step (B1) is formed by printing, spin coating, press bonding, or laminating.

11. The method as claimed in claim 6, wherein the formation of the resist layer openings in step (B1) are achieved by exposure and development.

12. The method as claimed in claim 7, wherein the removing of the resist layer is achieved by peeling, or stripping.