Conductive connection structure formed on the surface of circuit board and manufacturing method thereof

Abstract

The conductive connection structure of the present invention comprises a circuit board, a plurality of conductive pads, a solder mask layer, an electroless plating copper layer, and an electroless plating adhesive layer. The manufacturing method comprises the following steps: providing the circuit board having a plurality of conductive pads thereon; forming the solder mask layer, the electroless plating copper layer, and the electroless plating adhesive layer respectively on the surface of the circuit board, and forming a solder bump on the electroless plating adhesive layer. By the assistance of the conductive connection structure and the manufacturing method thereof, cavity otherwise formed on the conductive pads can be prevented, and the solder bumps therefore are firmly fixed on the conductive pads. Moreover, the stress in the surface between the solder bump and the conductive pad can be reduced as the semiconductor chip and the circuit board are combined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A˜1D are cross-section views of a conventional method of manufacturing a conductive connection structure ; and

FIGS. 2A˜2E are cross-section views of manufacturing a conductive connection structure of a preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

By the following specific embodiment, the present invention is put into practice. One skilled in the art can easily understand other advantages and efficiency of the present invention through the disclosed content of the specification. Through other different embodiments, the present invention can be carried out or applied. According to different observations and applications, all details of the specification can be modified and changed as not going against the spirit of the present invention.

With reference to FIGS. 2A˜2E, a manufacturing method of a conductive connection layer formed on the surface of a circuit board is provided in the present invention.

As shown in FIGS. 2A and 2B, a circuit board 201 and a plurality of connection pads 203 formed on the surface thereof are provided. The connection pads 203 are made of a material selected from the group consisting of copper, nickel, titanium, chromium, tin, or lead. In the present embodiment, the conductive connection pads are 203 composed of conductive copper.

Moreover, a solder mask layer 202 is formed on the surface of the circuit board 201. A plurality of openings 204 corresponding to the surfaces of the conductive pads 203 are formed on the solder mask layer to expose those surfaces.

In FIGS. 2C and 2D, an electroless plating copper layer 207 is formed on the surface of the conductive pads, and thickness thereof is between 7 and 15 μm. Further, an electroless plating adhesive layer 205 is formed on the surface of the electroless plating copper layer 207. The electroless plating adhesive layer 205 is made of a material selected from the group consisting of tin, silver, nickel/gold, titanium, tungsten, titanium/tungsten, chromium, aluminum, or organic solderability preservatives (OSP) etc.

Furthermore, as shown in FIG. 2E, a solder bump 206 is manufactured on the surface of the electroless plating adhesive layer 205. The solder bump 206 consists of one of copper, tin, lead, silver, nickel, gold, or platinum.

With reference to FIG. 2E, the structure made by way of the aforementioned manufacturing method in the present invention is the conductive connection structure formed on the surface of the circuit board. The structure includes: a circuit board; a plurality of conductive pads which are formed on the surface of the circuit board; a solder mask layer which is formed on the surface of the circuit board and forms a plurality of openings corresponding to the conductive pads to expose the surface thereof; an electroless plating copper layer which is formed on the surface of conductive pads; and an electroless plating adhesive layer which is formed on the surface of the electroless plating copper layer.

Because of the potential difference between the tin and copper metal balls, the copper atoms of the copper pads (the conductive pads) diffuse to the solder bump and this causes a metal alloy to be formed and the thickness of the copper pads decreases. The cavity is formed in the interface between copper and tin. By the aforementioned structure and manufacture thereof in the present invention, aforementioned problems are prevented, and the solder bump is fixed then forming a solder ball after reflow soldering.

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 conductive connection structure formed on the surface of a circuit board comprising: a plurality of conductive pads which are formed on the surface of the circuit board;a solder mask layer which is formed on the surface of the circuit board, and formed with a plurality of openings corresponding to the conductive pads to expose the surface thereof;an electroless plating copper layer which is formed on the surface of conductive pads ; andan electroless plating adhesive layer which is formed on the surface of the electroless plating copper layer.

2. The conductive connection structure as claimed in claim 1, wherein a solder bump is formed on the surface of the electroless plating adhesive layer.

3. The conductive connection structure as claimed in claim 1, wherein the conductive pad is made of a material selected from the group consisting of copper, nickel, titanium, chromium, tin, or lead.

4. The conductive connection structure as claimed in claim 1, wherein the solder mask layer is made of photosensitive resin.

5. The conductive connection structure as claimed in claim 1, wherein the thickness of the electroless plating copper layer ranges from 7 to 15 μm.

6. The conductive connection structure as claimed in claim 1, wherein the electroless plating adhesive layer is made of a material selected from the group consisting of tin, silver, nickel/gold, titanium, tungsten, titanium/tungsten, chromium, or aluminum.

7. The conductive connection structure as claimed in claim 2, wherein the solder bump is made of a material selected from the group consisting of copper, tin, lead, silver, nickel, gold, or platinum.

8. A manufacturing method of a conductive connection structure formed on the surface of a circuit board comprising the following steps: a) providing a circuit board with a solder mask layer and a plurality of conductive pads, wherein a plurality of openings are formed on the solder mask layer to expose the corresponding conductive pads;b) forming an electroless plating copper layer in the a plurality of openings on the conductive pads ; andc) forming an electroless plating adhesive layer on the surface of the electroless plating copper layer.

9. The manufacturing method of a conductive connection structure as claimed in claim 8, further comprising a step: c1) after forming an electroless plating adhesive layer on the surface of the electroless plating copper layer in step c), forming a solder bump on the electroless plating adhesive layer.

10. The manufacturing method of a conductive connection structure as claimed in claim 8, wherein the solder bump is formed through implanting, electroplating, or printing.