These connectors do not self align, so the placement has to be good initially. Connectors should be placed with 50µm accuracy. Not every assembly house can do this. However even with higher tolerances, the connection is normally stable. We had one customer, who made a mistake in layout, offsetting one connector 125µm in x and 125µm in y. He still had connections, but noticed this only on the MGTs. They failed with high data rates.
Regarding Samtec Product specification: In Revision F of this document 7.1.1 Samtec defines max allowed misaligned 0.03mm, in Revision D it was 0.08mm. Also the recommendation (7.3) you are referring was not there when we designed and tested this B2B interface. There is also a document describing general multiple connector applications: Furthermore we discussed with Samtec and got following hints: - The Multiple Connector Applications document covers the processing and layout requirements as well as we can. There are not any specific processing requirements for the SX5 components that are not covered in the document.
- The customer should verify that they are following the recommended PCB and Stencil Layouts: SS5, ST5.
- We have seen in our trials with lead-free solder that the components will have a tendency to stay right where they are placed. With a tin-lead soldering process, components are more likely to self-center.
- We recommend .005” Stencil thickness.
- If the components are not placed into the solder paste, but rather just sitting on top with no indentation of the paste, there could be more of a tendency to swim.
- If it is known that the placement is ‘perfect’, issues with the reflow oven could be causing misalignment: Vibration of the conveyor and/or imbalanced air flow from the convection fans.
As we saw the alignment issue with a few customers, we decided to make a sister series of TE0803, TE0807, TE0808 with other connectors. These are: TE0813 / TE0817 / TE0818 with self aligning Samtec ADM6 B2B connectors Samtec ADx have very good self alignment capabilities. We made tests with 6 connectors on one board, and there were no problems. The development of these boards is finished and the first boards will be produced in Q3 2021. If you have any reason for redesign anyway, you could consider using this series. We can sent you module footprint, if you want. |