Method for producing tiny soldered balls with repeatedly-usable substrates

Abstract

The invention relates to a method for manufacturing a small solder ball, in which a substrate is reusable. The invention is characterized in: firstly, the reusable substrate is prepared by means of IC manufacture process: a silicon wafer is used as a base, a metal conducting layer is sputtered from the front after heat oxidation treatment; secondly, the small solder ball is manufactured on the reusable substrate: a metal sacrificial layer is sputtered on the substrate to cover the opening of the conducting layer, thick photosensitive resist is coated and an electroplating window is photoetched, then solder is electroplated, the thick photosensitive resist is removed after electroplating, the solder is reflowed to form a solder ball, thereafter the metal sacrificial layer is corroded to be removed, so that the solder ball can drop off completely from the reusable substrate, and finally the solder ball is collected. According to the invention, the manufacturing procedure is simple and consumes small energy, the process has good controllability, the bottleneck of low productivity is overcome; the manufactured solder ball has smooth surface, good sphericity and uniform size, with the smallest grain diameter being 0.15mm.

Description

Technical field [0001] The invention relates to a method for preparing micro solder balls with a reusable substrate, which belongs to the field of electronic packaging. Background technique [0002] With the rapid development of consumer electronic products in the direction of "light, thin, short, small" and multi-functional, higher requirements are put forward on electronic assembly technology, forcing packaging technology to high-density, miniaturization, and integration. Evolution of direction. New high-density packaging technologies continue to emerge, and area array packaging forms such as Ball Grid Array (BGA) and Chip Scale Package (CSP) are the mainstream of future high-density packaging technologies. In the BGA and CSP packaging process, the replacement of pins with precision solder balls to achieve electrical and mechanical connections between the circuit substrate and the chip has become a key material for electronic packaging. Advanced electronic packaging has very st...

AI Technical Summary

Problems solved by technology

The main advantages of this method are good process controllability and high product yield, but it has obvious disadvantages at the same time: many preparation procedures, large equipment investment, high cost, and it is easy to introduce various ② The spray method is extended from the traditional powder preparation technology, which is characterized by strong production capacity but poor process controllability. In order to obtain solder balls in the required particle size range, it must go through multiple classification processes, which is easy to cause welding Oxidation and damage on the surface of the ball

The instillation method is to mold the molten metal with a fixed size. It is also characterized by strong production capacity, but the disadvantage is that it cannot effectively control the size and continuous growth of the droplets, and the solder balls have poor uniformity, low sphericity and surface oxidation.

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