Steve:
        Did not mean that they are unreliable, but they do put a lot of
stress on each and every barrel. On an about 150 pin connector we must press
with a force better than 2000 pounds on the connector to push through the
board. That is a lot of pressure.  Removing a connector is nearly impossible
and many times it destroys the barrels. Yes they go in very fast, but you
better do it right or you have good chances of scraping the board. I have
read extensively on how the connectors work. The company that sells this
connectors to us sent me several studies with magnified cross sections of
how the barrels end up. As Reuven says the tolerances for the barrel to be
are tight. Each pin puts pressure on two opposite sides of the barrels. If
it too small the pin may not fit and if it too large it may not put
sufficent pressure on the walls to create a cold fusion.  It also leaves the
barrel open from one end to the other. Some people do not like to have CC
inside the barrels because they believe wrongly that the CC might insulate
the connection.  This makes it extra difficult to build boards.

        Regards,
        Ramon



> -----Original Message-----
> From: Reuven ROKAH [SMTP:[log in to unmask]]
> Sent: Sunday, November 16, 2003 7:23 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Soldering Robots
>
> I agree, press fit is a good technology, some time the best when dealing
> with back planes 5 mm or more.
>
> the finish of the PCBs in press fit should be discussed and controlled.
>
>
> Best  Regards
>
> ROKAH Reuven
>
>
>
>
>                       Steve Gregory
>                       <[log in to unmask]         To:      [log in to unmask]
>                       OM>                      cc:
>                       Sent by: TechNet         Subject: Re: [TN] Soldering
Robots
>                       <[log in to unmask]
>                       >
>
>
>                       16/11/2003 03:33
>                       Please respond
>                       to "TechNet
>                       E-Mail Forum.";
>                       Please respond
>                       to SteveZeva
>
>
>
>
>
> Ramon,
>
> What kind of press-fits have you worked with? There are many different
> types
> out there that are VERY reliable! To make a general statement like you've
> made
> about press-fits, to me, shows that you haven't worked them very much. Can
> you share any specific data that shows them to be un-reliable?
>
> I only say that because we build various assemblies for Northrop Grumman
> that
> use press-fit connectors...
>
> -Steve Gregory-
> Dave:
>         They require a special tool to support the board and a press
> capable
> of  about 2000 - 3000 lbs thrust.   The stress that the press fit
> connectors
> put on each and every barrel is significant.  It leaves the barrel open
for
> debris, moisture and some people do not want CC inside of it. So to mask
> the
> board to prevent CC from going inside the barrels, can be a bear. Press
fit
> connector do not allow much  for mistakes.  I am partial to using solder
> doughnuts or solder robot.
>         Regards,
>         Ramon.
>
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