SMD USB-C sockets : no solder pads for mechanical strenght ? - Page 1
Forum section: electronics / beginners

author: ratatax
author_rank: Regular Contributor
timestamp: October 26, 2020, 01:22:15 pm
content: I'm looking for USB-C SMD sockets, they almost all share the same four metal prongs :But they aren't long enough to get through a 1.6mm thick PCB. I'm wondering why they don't simply put horizontal metal legs that can be soldered like any other SMD pad.Currently the port can be easily ripped out since it's only held down by its power/data pins.I'm thinking about adding a big recangular pad under the connector with solder paste to completely solder it to the board. Would that be a reasonable idea ?

author: wizard69
author_rank: Super Contributor
timestamp: October 26, 2020, 04:32:26 pm
content: Good question as this seems to be a common issue with many port types not just USB-C. The problem of mechanical integrity is why I really don't like USB-C.In an event I don't think that going all the way through the board is a huge problem. As long as some solder wicks up into the vias they are plugged into you should get some mechanical strength. It would certainly be better than Surface Mounting pads. Surface mount devices do not have the mechanical strength of posts like this.Of course the bigger issue is that USB-C sucks mechanically and one is just as likely to break off a connector in the receptacle or just have it pull out. Some times I think the guys that did USB-C just wanted to make sure that DB style connectors never die.

author: thm_w
author_rank: Super Contributor
timestamp: October 26, 2020, 09:30:32 pm
content: As wizard says the pins going through the board, even if only partially, are much stronger than a few mm SMD pad.Can you post a photo of how you've soldered it?

author: ataradov
author_rank: Super Contributor
timestamp: October 26, 2020, 09:32:25 pm
content: It is much better mechanically to have them be attached to the plated hole with a copper ring on both sides. The  though hole pins must be soldered, of course, so mechanically connector is held by the case, not by the data pins.I'm not sure what people are doing with their electronics. I have never seen connectors fail in normal use.

author: tooki
author_rank: Super Contributor
timestamp: October 26, 2020, 10:48:35 pm
content: Quote from: ratatax on October 26, 2020, 01:22:15 pmThere are plenty of models with pins made to extend through a 1.6mm PCB. I had no trouble finding them on Digi-Key. Many jacks are available in various leg lengths to accommodate different PCB thicknesses. If you didn't find any, it's because you didn't really look.Quote from: ratatax on October 26, 2020, 01:22:15 pmBecause solder joints alone aren't all that strong. The joint needs to have some mechanical stabilitywithoutthe solder. The solder just keeps it in place. (And connects it electrically of course.) USB connectors are subject to a lot of forces in every direction, which is a challenge for even the best PCBs. A purely surface mount jack would not be very reliable, as either the solder itself would eventually crack, or the copper would delaminate from the board. As others said, the through-hole is much, much stronger.Quote from: ratatax on October 26, 2020, 01:22:15 pmNot really, unless the connector was expressly designed to be mounted like that.

author: Unixon
author_rank: Frequent Contributor
timestamp: October 27, 2020, 12:17:48 am
content: Quote from: ratatax on October 26, 2020, 01:22:15 pmThis one isn't bad at all, even soldered half-board deep these four stubs will hold it tight.Even if you solder entire socket bottom to an SMD pad, this will be a weaker joint than four TH pins.