Component Body Lifting

摘要

THIS MONTH WE illustrate an example of what appears at first glance to be poor lead solderability. When examined, however, it is a combination of component and pad design. FIGURE 1 shows the lead to be floating in the sol-der joint, suggesting poor wetting. When we examine the component lead and plastic body, however, the lead is not parallel, so it always sits off the pad surface, even if perfectly soldered. The lead sits in a cavity in the component body to maintain its position. But with the size of the pad used in the design and a full solder paste print, the component body will always lift. To improve the component, the position of the pin should be parallel with the body. Ideally the opening of the body of the lead should be wider or angled to permit solder to wet without lifting the part. A simple shop-floor fix is to order another stencil and reduce the width of the paste print, decreasing the lift dur-ing reflow.