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| Date: | Thu, 12 May 2011 13:32:30 -0700 |
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Man, he knows too much!
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu May 12 12:58:52 2011
Subject: Re: [TN] Under Pressure
Typically, the PWB is supported by a nest with holes drilled in it that accommodate the pins coming through the holes in the PWB. This prevents the PWB from any significant bending or warping. The nest has tooling holes to hold the PWB in place so the PWB connector holes are lined up with the holes in the nest. A second set (or sometimes the same pins) guide the ram, if necessary.
Then, to prevent undue force on the PWB from the bottom of the connector body (or in this case from the bottom of the metal block), a shut height is used in the press to control the press ram from pushing the metal block down any further than is needed to seat the block.
Some presses have the option of using either a mechanical shut height OR a programmable Z-axis point where the ram is tripped off.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, May 12, 2011 2:38 PM
To: [log in to unmask]
Subject: [TN] Under Pressure
We have a high power application where the engineers want to use press-fit
components that are like metal blocks with a grid of pins underneath that
need to be smooshed into the board. You can see a picture at
http://frontdoor.biz/PCBportal/wurth.jpg
The manufacturer gives enough data about insertion force and max torque and
all that, but it just got me wondering... some of these devices have 36 pins
and at 250 N per pin (max) this seems like a lot of pressure. Can boards be
damaged by so much pressure? (assuming we prevent warping). Seems like there
would have to be some limit to compressive force on laminate, but I've never
heard anyone mention it.
Jack
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