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September 2006

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Subject:
From:
"Tempea, Ioan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Tempea, Ioan
Date:
Wed, 6 Sep 2006 08:07:21 -0400
Content-Type:
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text/plain (97 lines)
You're right Inge, I will expand:

the connector has been chosen with locking pins that are shorter than the thickness of the PCB, therefore only locking through friction.No sliding guides, the mating is through manual, direct insertion. When mating, the joints break. 
The "pins" for the lower row of contacts are shorter than the ones for the higher row. Therefore, out of 10 contacts, only 5 are in intimate contact with the pads, the other 5 form joints, but by means of a higher layer of solder.
The board finish is ENIG.

Right now, the stencil apertures are 1:1, the solder wets on the whole pad, which is about the double of the length of the pin, but the bulk of solder is in the joint area, so it looks like not enough solder, even though there's wetting on pad and pin.
At NPI stage, this connector has been hand soldered and it did not break, according to the NPI team. Now, in production, there's something else. So bigger volume of solder seems to help.

This connector mates 2 cards, a brain assembly and a connector assembly. It is the only point of contact. Mating the connector card with cables will send stress to this connector. Also, some assemblies might get outdoors.

So anyways, my trouble is that the connector joints break at assembly.

Thanks,

Ioan

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Ingemar Hernefjord
(KC/EMW)
Sent: Wednesday, September 06, 2006 7:09 AM
To: [log in to unmask]
Subject: Re: [TN] Connector reliability


The reliability is based on a number of parameters, humidity, vibration,
shock, handling, corrosivity and a lot more, so, your question depends
on....
Generally spoken, butt joint PWB connectors are not allowed for MIL use.
If you look at Amphenol's (US biggest on MIL conns) homepages, you'll
find zero butt joint connectors for PWBs. There must be a reason why.
For commercial use, I can imagine butt joint connectors are very
welcome, because they match rapid robotic mounting. So, for home
electronics and commercial things in general, they are probably reliable
enough. 

Your question can only be answered in general terms, because we don't
know anything about the sliding mechanisms when mating, nor how the body
is meant to be secured vs. the board etc. I've been working a lot with
connectors in "my former life" and I have seen how complicated the
verification of a connector series can be.

Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: den 5 september 2006 22:31
To: [log in to unmask]
Subject: [TN] Connector reliability

Hi Technos,

I would like what you think about the reliability of the joints formed
by this connector http://samtec.com/ftppub/pdf/SFMH_SM.PDF

It looks pretty much like a butt joint to me, no real compliance.

And since we're here, what about SMT headers, with their massive pins,
are they reliable?

Thanks,

Ioan

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