brianjaod
Posts: 5
Joined: Thu Aug 03, 2017 4:34 pm

Desperate for vertical sodimm CM3 connector! Can you help?

Thu Aug 03, 2017 5:01 pm

Hey all,

I'd really appreciate the community's help on this, so thanks in advance! I'm in desperate need of a few samples of a vertical (not right angle) DDR2 sodimm connector for the CM3. I just got proto boards back and realized that I sourced a DDR style, instead of the slightly different DDR2, which means that I can't even connect in the pi module for testing until I get the right connector. Unfortunately, I've searched the world over and cannot find any available stock of the vertical style connector. In fact, even finding a manufacturer with a compatible part has been really tough, and has only distilled down to two: Kyocera 6409 (http://global.kyocera.com/prdct/electro ... /6409.html) and TE 2040910-2 (http://www.te.com/usa-en/product-2040910-2.html). And with those, neither company has any stock anywhere in the world, including Asia. In fact, TE has said that that part was discontinued because of lack of interest with no orders for years, apparently.

There are a ton of right angle options that fit the DDR2 CM3 style, but essentially none of the vertical style. The problem with that, (and there's no way that I can be the only one with this problem, I hope) is that the right angle style takes up A TON of board real estate. Yeah you can run traces under the module, but that's about it. Plus, a right angle design is also a lot less optimal from a thermal point of view, which is particularly important for the compute module. The reason for this is that if you attach a heat sink to the Broadcom and the module is standing vertical, then the natural convection air flow will do much better for cooling compared to if the heat sink is oriented horizontally.

The bottom line is that I'm in urgent need of getting at least a handful of vertical connector samples for testing of these proto boards. I certainly can't be the only one that's need to design the CM3 with a vertical orientation, right? Anybody out there have some extras that I could buy (at a premium, if necessary) from them? Or other ideas? Thanks so much!


brianjaod
Posts: 5
Joined: Thu Aug 03, 2017 4:34 pm

Re: Desperate for vertical sodimm CM3 connector! Can you help?

Fri Aug 04, 2017 7:19 pm

Thanks aBUGSworstnightmare for the reply! Yes, I did exhaustively search the forum, including that thread, but unfortunately red_mamba's fix on that connector isn't reliable, in my experience, because I tried the same thing with the same connector. It might sort of work for a one-off prototype, but not production. In fact, I'll reply to that thread too, to report on my solution, in case it's helpful to anyone.

The good news was that I was able to find a solution! Thanks to Briarios and his other thread (viewtopic.php?f=98&t=80708), where he generously shared his project BOM (http://rpi.pmfg.me/), which uses this new JST connector (DM-7D4-H2400; http://www.jst-mfg.com/product/detail_e.php?series=520), which I had not found before. His BOM shows him sourcing it from Taobao (https://world.taobao.com/item/148557631 ... s=1#detail), and it gave the part number, allowing me to contact JST directly about getting samples here in the US. Unfortunately, I couldn't find any stock from Digikey (or others), but JST was able to send me some samples, as well as confirm that they have available production stock in Asia. So phew, I'm saved! Thanks all!

As far as the other parts from Kyocera and TE, I still haven't been able to find any stock anywhere, but this JST solution is legit and gets me on my way. Thanks again to all!

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