Improvement of the auto wire feeder machine in a de-soldering process

Abstract

This paper presents the methodology of the de-soldering process for rework of disk drive Head Stack Assembly (HSA) units. The auto wire feeder is a machine that generates Tin (Sn) on the product. This machine was determined to be one of the major sources of excess Sn on the HSA. The defect rate due to excess Sn is more than 30%, which leads to increased processing time and cost to perform additional cleaning steps. From process analysis, the major causes of excess Sn are as follows: 1) The machine cannot cut the wire all the way into the flux core area; 2) The sizes and types of soldering irons are not appropriate for the unit parts; and, 3) There are variations introduced into the de-soldering process by the workforce. This paper proposes a methodology to address all three of these causes. First, the auto wire feeder machine in the de-solder process will be adjusted in order to cut wires into flux core. Second, the types of equipment and material used in de-soldering will be optimized. Finally, a new standard method for operators, which can be controlled more easily, will be developed in order to reduce defects due to workforce related variation. After these process controls and machine adjustments were implemented, the overall Sn related problems were significantly improved. Sn contamination was reduced by 41% and cycle time was reduced by an average of 15 seconds.

Keywords

• Auto wire feeder
• Flux
• Tin
• De-soldering process
• Rework process