The SMT header assembly for press-fit pins of Zierick employs capillary effects to significantly improve the strength of the solder joints. The top of the board has a circular pad, the bottom a square pad. The four cavities between the square pin and the round plated through-hole draw the solder to the top. Thus, capillary action pulls the assembly tightly to the board and into the correct position over the solder pad even if placed off center. A ring of solder is formed around the pin indicating that the reflow process is complete. This results, according to the vendor, in a pin retention force 50% higher than that with J-type headers, and it also eliminates coplanarity problems. Board placement tolerances are increased. The header base consists of the same material as the PCB, which avoids thermally induced stress effects (TCE). The header mounts come with various numbers of rows, pins per row, pin center, pin lengths and finishes.
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