Pad Metallurgy Used: Copper OSP pads were used for all of the results that I have been reporting. The same design test boards with Nickel/Gold pads are available and awaiting further assembly tests. I will consult with a board technology and metallurgical expert concerning your question about tin plating and post a response later on. Is your question about this targeting the current industry capability of using tin plating technology on such small pad dimensions?
Printhead: The 0201 assembly defect trend data shared was generated using 60-degree metal squeegee blades. In parallel with this, printing tests have also been performed using enclosed pressurized printhead technology. Both systems produce equivalent results for printing 0201 boards.
Some reasons one may consider using the enclosed printhead system over squeegees include:
1. Apertures that are designed with more challenging area ratios (i.e. smaller openings and/or thicker stencil) may see improvements in transfer efficiency from the enclosed printhead system, as this provides more direct pressure on the material to fill the apertures completely.
2. More efficient utilization of the solder paste material on the stencil with less waste generated.
3. Solder paste material is expected to have longer stencil life, since it is protected from exposure to the ambient in a sealed chamber.
Further enhancements to the present day standard enclosed printhead system are expected to show better print definition and volume scatter control compared to squeegees, which I look forward to sharing soon.
-Jeff
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