Electrical connector with multilayer surface treatment and method for fabricating the same

An electrical connector includes an insulative housing (3), a number of contacts (4) retained in the insulative housing (3) and a metallic shell (1) enclosing the insulative housing (3). The metallic shell (1) includes a number of peripheral walls and a soldering tab (15) extending therefrom. Each of the soldering tab (15) and the peripheral walls includes an intermediate layer (20), a first plating layer (21), a second plating layer (22) and a third plating layer (23). The third plating layer (23) covers both inner and outer sides of the second plating layer (22) of the peripheral walls for enhancing anti-wear properties while leaving the second plating layer (22) of the soldering tab (15) uncoated for wetting. Besides, a method of surface treatment of the metallic shell (1) is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to an electrical connector, and more particularly to an electrical connector having a metallic shell of multilayer surface treatment and a method for making such metallic shell.

2. Description of Related Art

Conventional electronic devices, such as mobile phones, usually have black appearance. In order to match with such color, electrical connectors outwardly exposed on such black electronic devices should have black surface treatment.

Nowadays, in industry, back surface treatment technologies usually include black electrophoretic coating treatment, directly plating black nickel treatment and directly plating black titanium treatment. Take the black electrophoretic coating treatment for example, in such treatment, an insulative layer is formed on peripheral sides of a metallic shell of an electrical connector. However, such insulative layer can not meet electrical conduction requirement and mostly importantly, its anti-wear capability is poor. In a word, the metallic shell treated under conventional back surface treatment technologies exists poor soldering capability and poor anti-wear capability and is not suitable for being applied in current electronic devices.

Hence, it is desirable to provide an electrical connector with improved surface treatment and a method for making the same.

BRIEF SUMMARY OF THE INVENTION

The present disclosure provides an electrical connector including an insulative housing, a plurality of contacts retained in the insulative housing and a metallic shell enclosing the insulative housing. The metallic shell includes a plurality of peripheral walls jointly forming a receiving cavity and a soldering tab extending from one of the peripheral walls to be soldered to a circuit board. Each of the soldering tab and the peripheral walls includes an intermediate layer made of a first material, a first plating layer made of a second material, a second plating layer made of a third material and a third plating layer made of a fourth material. The third material is of robust soldering capability and the fourth material is of robust anti-wear capability. The first plating layer covers both inner and outer sides of the intermediate layer of the soldering tab and the peripheral walls. The second plating layer covers both inner and outer sides of the first layer of the soldering tab and the peripheral walls. The third plating layer covers both inner and outer sides of the second layer of the peripheral walls for enhancing anti-wear properties while leaving the second layer of the soldering tab uncoated for wetting.

Besides, the present disclosure provides a method for surface treatment of a metallic shell of an electrical connector. The method includes the steps of:S1) providing a metallic shell stamped from a first material, the metallic shell being provided with a plurality of peripheral walls and a soldering tab extending from one of the peripheral walls to be soldered to a circuit board;S2) plating a first plating layer of a second material on both inner and outer sides of the soldering tab and the peripheral walls;S3) plating a second plating layer of a third material on both inner and outer sides of the first plating layer of the soldering tab and the peripheral walls, the third material being of robust soldering capability;S4) shielding the soldering tab so as to be uncoated in subsequent steps;S5) plating a third plating layer of a fourth material on both inner and outer sides of the second plating layer of the peripheral walls, the fourth material being of robust anti-wear capability; andS6) cleaning the foregoing shielded soldering tab to expose the second plating layer thereon.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawing figures to describe the preferred embodiment of the present disclosure in detail. As shown inFIGS. 1 and 2, the illustrated embodiment of the present disclosure discloses an electrical connector100including an insulative housing3, a plurality of contacts4retained in the insulative housing3and a metallic shell1enclosing the insulative housing3. The electrical connector100is a standard Micro USB connector and is soldered to a circuit board (not shown) of an electronic device (such as a mobile phone). The electrical connector100is usually exposed to the electronic device and functions as a data-transmission port or a charger port.

Referring toFIGS. 6 and 7, the metallic shell1includes a top wall11, a bottom wall12, a pair of side walls13connecting the top wall11and the bottom wall12, a plurality of extending portions14horizontally extending from the side walls13, and a plurality soldering tabs15located at distal ends of the extending portions14. Each soldering tab15extends along a vertical direction for being inserted through the circuit board before getting soldered. The top wall11, the bottom12and the pair of side walls13jointly form a receiving cavity10for receiving a plug connector (not shown). Each of the top wall11, the bottom12and the pair of side walls13can be regarded as a peripheral wall. The top wall11defines a pair of locking holes111in communication with the receiving cavity10.

Referring toFIG. 10, each of the peripheral walls, the extending portions14and the soldering tabs15includes an intermediate layer20made of a first material (such as iron or stainless steel), a first plating layer21covering both inner and outer sides of the intermediate layer20, a second plating layer22covering both inner and outer sides of the first plating layer21, and a third plating layer23covering both inner and outer sides of the second plating layer21of the peripheral walls and the extending portions14. The foregoing-mentioned “inner and outer sides” are “top and bottom sides” of the illustrated embodiment of the present disclosure. The first plating layer21is made of a second material which is a nickel alloy of the illustrated embodiment. The second plating layer22is made of a third material which is gold or tin of the illustrated embodiment. The third plating layer23is made of a fourth material which is black titanium or black nickel of the illustrated embodiment.

The first plating layer21coated on the intermediate layer20is for providing a suitable substrate for easily coating the subsequent second plating layer22. The second plating layer22, on one hand, improves the soldering capability of the soldering tabs15, and on the other hand, improves the integral conductive capability of the metallic shell1. The third plating layer23, on one hand, presents the metallic shell1of black color so as to keep it in accord with the color of the electronic device, and on the other hand, improves the anti-wear capability of the metallic shell1. The “back color” includes matted black.

It is noted that the third plating layer23is uncoated on the second plating layer22of the soldering tabs15in order to prevent that the third plating layer23weakening the soldering capability of the soldering tabs15.

When the electronic devices are of back colors, through the structure of the metallic shell1of the present invention, the metallic shell1not only has robust conductive capability, robust soldering capability and robust anti-wear capability, but also the color of the metallic shell1can be in accord with the color of the electronic devices.

Referring toFIGS. 3 to 11, the present invention discloses a method for surface treatment of a metallic shell1of an electrical connector100. The method includes the steps of:S1) providing a metallic shell1stamped from a first material, the metallic shell1being provided with a plurality of peripheral walls and at least one soldering tab15extending from one of the peripheral walls to be soldered to a circuit board;S2) plating a first plating layer21of a second material on both inner and outer sides of the soldering tab15and the peripheral walls;S3) plating a second plating layer22of a third material on both inner and outer sides of the first plating layer21of the soldering tab15and the peripheral walls, the third material being of robust soldering capability;S4) shielding the soldering tab15so as to be uncoated in subsequent steps;S5) plating a third plating layer23of a fourth material on both inner and outer sides of the second plating layer22of the peripheral walls, the fourth material being of robust anti-wear capability; andS6) cleaning the foregoing shielded soldering tab15to expose the second plating layer22thereon.

In the step S2), the second material of the first plating layer21is nickel alloy. In the step S3), the third material of the second plating layer22is gold or tin. In the step S5), the fourth material of the third plating layer23is black titanium or black nickel, and the third plating layer23is fabricated by Physical Vapor Deposition (PVD) vacuum plating technology. Because the process temperature of the PVD vacuum plating technology is high (near 400° C.), it requires the third material of the second plating layer22has high temperature resistance. According to the preferred embodiment of the present invention, under this processing method, gold is selected as the third material of the second plating layer22. However, in other embodiments, the third plating layer23can be fabricated by chemical plating technology. Because the process temperature of the chemical plating technology is usually low, under this condition, either gold or tin can be selected as the suitable material of the second plating layer22.

In the step S4), the soldering tab15is coated by a protective sleeve or is adhibited by a protective membrane. Correspondingly, the step S6) includes removing the protective sleeve or the protective membrane. However, in alternative embodiments, in the step S4), the soldering tab15can be protected by a kind of lipid. Correspondingly, the step S6) includes removing the kind of lipid.

It is to be understood, however, that even though numerous, characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosed is illustrative only, and changes may be made in detail, especially in matters of number, shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broadest general meaning of the terms in which the appended claims are expressed.