ALUMINUM-PLASTIC COMPOSITE STRUCTURE

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional application of U.S. patent application Ser. No. 13/074,134, filed on Mar. 29, 2011.

BACKGROUND

1. Technical Field

The present disclosure relates generally to an aluminum-plastic composite structure.

2. Description of Related Art

Many aluminum-plastic composite structures used in electronic devices include a metal member and a plastic member fixed on the metal member. The plastic member is adhered on the metal member by glue. However, strength of the bond formed using the glue will decrease over time, and may result in detachment of the metal member from the plastic member.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views.

FIG. 1 is a cross section of an embodiment of an aluminum-plastic composite structure.

FIG. 2 is a flowchart of a method for making the aluminum-plastic composite structure.

DETAILED DESCRIPTION

Referring to FIG. 1, an embodiment of an aluminum-plastic composite structure 200 includes an aluminum portion 21 and a plastic portion 23 integrally formed on the aluminum portion 21 by insert-molding technology. The aluminum portion 21 includes a joining surface 210. The aluminum portion 21 includes a plurality of micro grooves 211 in the joining surface 210 made by using ultraviolet lithography. A width of each micro groove 211 is in a range from about 0.02 millimeters to about 0.05 millimeters, and a depth of each micro groove 211 is in a range from about 0.2 millimeters to about 0.25 millimeters. Thus, the plastic material can be injected effectively into the micro grooves 211 to enhance strength of the bond formed between the aluminum portion 21 and the plastic portion 23. In this embodiment, a ratio of the depth to the width is equal to or greater than about 10. In the illustrated embodiment, the aluminum portion 21 is a sheet, and the depth of the micro grooves 211 is less than about 80% of the thickness of the aluminum portion 21 where the micro grooves 211 are defined to maintain bonding strength of the aluminum portion 21 with respect to the plastic portion 23. The aluminum portion 21 may be made of aluminum or aluminum alloy, the micro grooves 211 may be easily defined because of the cubic crystal structure of aluminum.

Also referring to FIG. 2, a method for making aluminum-plastic composite structure follows.

In step 201, an aluminum portion 21 is provided, and the aluminum portion 21 includes a joining surface 210;

In step 202, a plurality of micro grooves 211 are formed in the joining surface 210 by ultraviolet lithography, a width of each micro groove is in a range from about 0.02 mm to about 0.05 mm; a depth of each micro groove is in a range from 0.2 mm to 0.25 mm. The process of ultraviolet lithography for defining the micro grooves 211 includes the following steps:

(1) Photoresist is covered on the joining surface 210 of the aluminum portion 21.

(2) An optical mask is formed on the joining surface 210 of the aluminum portion 21, and the aluminum portion 21 is placed in an ultraviolet exposure machine for UV exposure.

(3) The aluminum portion 21 is etched in an etching fluid in a cavity to form the micro grooves 211, in which a size of the micro groove is being controlled by adjusting the concentration of the etching fluid and/or an etching duration.

In step 203, the aluminum portion 21 is positioned in a mold, and then the melt plastic material is injected on the aluminum portion 21 to form a plastic portion 23. The plastic material is injected and substantially filling into the micro grooves 211, thus the plastic portion 23 can be bonded or fixed on the joining surface 210 of the aluminum portion 21.

In step 204, the plastic portion 23 is cooled to form the aluminum-plastic composite structure 200.

The aluminum-plastic composite structure 200 defines the micro grooves 211 at the joining surface 210 of the aluminum portion 21 in which the plastic material is embedded, thus firmly fixing or bonding the plastic portion 23 on the aluminum portion 21, and increasing the bond strength between the aluminum portion 21 and the plastic portion 23.

The aluminum-plastic composite structure 200 also has a reduced thickness because no latching mechanism is included.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages.