應用於電子產品外殼之5052鋁合金與ABS塑膠超音波焊接技術之研究

Abstract

因電子產品講求輕薄短小，金屬外殼儼然成為主流，但因傳輸速度的需求，使金屬電磁遮蔽效應更加嚴重，以致產品外殼上需要塑膠構件供電磁訊號穿透，為了能讓金屬與塑膠有效的接合，異質材料接合技術將是決定電子產品設計之關鍵。 超音波焊接提供了一個良好異質材料熔接方式，其原理是利用微孔洞機械固錨法接合兩者材料，並可藉由改變表面粗糙度與電化學處理等方式來提升接合強度。 本研究使用5052鋁合金與ABS塑料，以窗型對接法進行接合，配合砂紙研磨以及陽極氧化處理來製造奈米等級的孔洞，並交叉探討不同表面粗糙度與陽極處理電壓之大小，對孔洞型態生成與整體接合強度之影響。 結果顯示，經電化學加工後之表面粗糙度與接合強度並無明顯關聯。而在接合面受力的情況下進行超音波震盪會破壞陽極孔洞，使兩者無法接合。但若是使用超音波剪切擠入以垂直方向填入塑料，便可在不破壞陽極孔洞的情況下有效提升接合力，且可以藉由平整的鋁合金表面以及較大的工作電壓得到更高的接合強度。在適當參數之下，其平均接合強度可達1.8Mpa。

關鍵字： 超音波焊接、異質材料接合、鋁合金、陽極氧化、表面粗糙度、ABS、奈米孔洞、固錨力。

By chasing for compact and slim electronic device, nowadays, metal housing has become the mainstream. However, higher transmission speed has to face a new issue - the metal electrical shielding. It means combining a plastic component at housing is necessary. Therefore, the technology of Hybrid joint or how to effectively bond plastic and metal is a key of designing an electronic device in the future. Ultrasonic welding provides a good way for Hybrid joint. The principle of it is using microvoids interlocking to bond two materials, it also can change surface roughness and electro chemical machining to improve the bond strength. This paper is mainly focused on window type abutting joint between Aluminum 5052 alloy and Acrylonitrile Butadiene Styrene (ABS), and builds nanostructure voids on the surface of aluminum by using sandpaper and anodic aluminum oxidation (AAO), then cross compare the structure of voids and bond strength with different surface roughness and working voltage of AAO. The result shows that there has no relation between the bond strength and the surface roughness after AAO. If the ultrasonic welding applied on the joints under pressure, AAO will be destroyed, the bonding will fail. However, if using ultrasonic cutting extrusion with vertical angle, the AAO won’t be destroyed, the bond strength will increase. Moreover, bond strength can be improved by higher voltage and lower roughness. With appropriate parameters, the bond strength can reach to 1.8Mpa overall.

Keyword： Ultrasonic welding, Hybrid joint, Aluminum, Anodic Aluminum Oxidation, Surface roughness, ABS, Nanostructure voids, Interlocking.