PCBA Manufacturing DFM Notes: Packages for 0603C
In the PCBA manufacturing process, sometimes there will need some DFM(Design for Manufacturability) modification to increase the PCBA board's pass rate, this article is a DFM note for the 0603 capacitor's package for the PCB designers.
1. Overview: 2%~3% PCBA Boards fail in the test, even the pads get off
Once in a 1000 pcs PCBA production, we found that there a cap easy to fail off from the PCBA board, with our SMD soldering strength testing, there will be about 2%~3% boards not pass this test, and even the pads on board GET OFF...
This is really a high rate for the PCB assembly, then Makerfabs engineers checked the PCB design files, we found that there the capacitor package on the board too small! 60 mils by length and 36 mils by width.
Normally, for 0603 capacitors (60 mils by length and 30 mils by width), to ensure the soldering strength, it is better to make the solder paste surround the whole pads, that is, while the capacitor length 60 mils, it is better to keep the pads distance outline larger, at least 75 mils, a standard 0603 capacitor package design such as below:
2. DFM updates in the PCBA production
So in the PCB production, we enlarged the capacitors’ pads, to make the outer line distance from 63 mils to 75 mils:
With these DFM updates in the PCBA production, the 0603 capacitor’s soldering strength much more firm, and the problem of C1 falling off rate reduces a lot.
3. The PCBA Board Comparison:
PCBA Board - Original Design: PCBA Board - With Makerfabs DFM:
4. Suggestion to PCBA Designers:
→ For 0603 resistor/capacitor, the outline distance for pads at least 75 mils, suggest 90 mils. And suggest 60 mils for 0402.