Fred Merkle wrote on Mon, 22 May 2006 16:59 |
What do you expect the jack to be supported by? The PCB? I think there's still very good reason for using nuts as physical attachment points to provide support. Secondly, I also believe that in terms of shielding and immunity, having a metal jack and jack nut with properly masked chassis (or lock washer of sorts) is far superior to plastic jacks. I'm especially concerned about it in this day and age of GSM.
I certainly agree with you though, that metal or plastic jacks provide very little insight into the quality of the overall mechanical design. There are always price points and manufacturing constraints to deal with.
-Fred
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I am not going to write a tutorial on packaging and there are folks much better than I at that game, but better 1/4" jacks have screw bosses in them so they can be screwed down to the PCB. Even lower labor approaches involve solid bosses that nest into holes in the PCB to strain relief the forces from insertion/removal cycles. The fastest way to fatigue and trash a solder connection is to make it structural. Likewise if you have tens of 1/4" jacks in a PCB you need to resist the temptation to use that for fastening, although I suspect many smaller low cost (disposable) products do that (who me?
) .
What exactly do you expect the metal barrel on a 1/4" jack to shield, the ground lead? With modern powder coating and metal treatments getting a proper ground even with metal nuts isn't insured. Good quality plastic jacks can even have special piercing ground contacts to cut into the panel chassis and make a decent quality ground connection. This is often adequate for shielding, not for high current safety ground bonding.
I will concede that I have used a metal barrel 1/4" jack on a low end fixed installation product (something like a 2W or 5W amp and I think I used a high current speaker jack)) for safety ground bonding and it passed agency testing, but that was a very small, very sharp pencil product, and not IMO best practice.
If you're a customer tho' of course you're right.
JR