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Molex’s Solder Charge Interface |
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Friday, 01 August 2008 |
Solder Charge PCB interface optimizes benefits of density of a BGA tail, but improves on the latter’s shortfalls in processing and manufacturing. The concept consists of a blanked solder mass that gets extruded through a hole near the tip of a terminal until it fills a volume on the opposite side of the pin. The chamfer on the Solder Charge side of the hole provides retention and prevents the solder from backing out of the terminal. While a BGA is manually placed and then heated to adhere to the j-lead on the bottom of a connector, the novel interface is more precise as it uses stamping equipment for adhesion to the terminal, whereas with a stamping die one can be precise to a reported 0.0001". Further, it permits the transmission line to directly reach the PCB, minimally disrupting the design and maintaining the system’s electrical properties.
Solder Charge uses standard reflow processing, and reflow profiles are available for all common products. It extends slightly beyond the tip of the terminal to seat within the solder paste on the solder pad; the terminals will lower onto the pad within the reflow oven. In reflow, the solder forms a bugle-shaped solder fillet, providing a 360° engulfment around the terminal and through the hole in the pin for added retention strength. Additionally, the interface is said to provide a significant amount of forgiveness to compensate for variability in the PCB flatness, giving added assurance the PCB adhesion will work.
Incorporating the technology is said to offer several benefits over standard BGA attachments, including:
- A mechanical design that permits post-processing visual inspection, limiting the need for x-ray.
- Increased PCB retention strength – roughly three times as strong as typical BGAs – that reduces stress on solder joints, increases compliancy and lowers applied costs.
- Reduced cycle times and fewer rework and secondary processing steps that promote increased output.
- Precise formation of stamping die, which offers enhanced precision in the Solder Charge formation and adhesion process.
- Flexible solder mass that compensates for board warping.
The interface comes in the HDMezz and SEARAY(1) connectors, in new designs in development, and in SnPb or Pb-free designs.
Available from Molex (molex.com).
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