[BC] Soldering D-sub Pins

[Gregory Muir]

Most of the commercial crimp-style connectors available nowadays (mostly 
never identified as to the [Taiwan] manufacturer they were purchased from) 
that contain the punched and formed hollow sheet metal style of contact that 
we are accustomed to are not considered as reliable as opposed to the 
solid-contact varieties specified in many standardization documents (the 
MIL-DTL-83513 series comes to mind) mainly because of the style of 
interface between the conductor and the crimped portion of the contact and, 
secondly, the contact mating forces involved.  The first item is due to the 
"squishing" compression force obtained as the sheet metal surface rolls over 
the conductor under pressure from basically two to three die surfaces with 
the punched contact.  On the other hand, the screw-machined contact uses 
more of a captive arrangement with an entirely closed crimp chamber and 
crimp forces applied equally around the circumference of the conductor from 
several sides normally provided by a 4-, 6- or 8- indent crimp method of 
which Daniels was one of the forerunners in earlier days.  Although both 
methods yield a reliable crimp joint under most circumstances, severe 
operational environments will begin to show the differences.

Secondly, the reliability of a punched and formed contact can become suspect 
in highly demanding environments due to the ability of contaminants to ender 
from the rear of the connector and migrate down through the hollow core of 
the contact.  This can cause early intermittents and such if not carefully 
watched.  That is why both commercial and military standards call out the 
use of solid style contacts (either solder or crimp) when environmentally 
sealed connections are required.

Many high-reliability connectors use a straight- or twisted-wire spring 
contact design to increase mating contact pressure and decrease contact 
electrical resistance.

Greg Muir




----- Original Message ----- 
From: "Peter" <peterh5322 at rattlebrain.com>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Sent: Friday, April 11, 2008 11:05 AM
Subject: Re: [BC] Soldering D-sub Pins


>
> On Apr 11, 2008, at 9:06 AM, Gary Glaenzer wrote:
>
>> wasn't the crimp connection developed during WW-2 to cut down the 
>> required soldering in
>> military aircraft systems ?
>
> Probably the "screw machined" pins and Daniels-type crimper.
>
> The "precision formed" connector was post-War, and was an AMP 
> development, and which requires a different crimper.
>
> The screw machined pins are still required in many applications.
>
>
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