[PCB_FORUM] Re: AMC format

Gary,

 

I've done a few custom connectors like this.  IMO, there is no need for the
section closest to the card edge so I would design it out.  I put a pin
escape via just above each connector pin and routed a trace back off the
card edge (one for each signal) on an internal layer in the center of the
stackup for a plating bar.  I let the fabricator bring the plating bar out
to the external layer of their choice.  Putting the plating bar in the
center of the stack-up prevents the traces from being exposed after the
chamfer is added.  This will cause a fairly long stub on each signal pin so
make sure you check with engineering prior to using this method.

 

Make sure you put a no route area on that layer under the connector pins
prior to routing.

 

Jeff

 

  _____  

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Peter Hughes
Sent: Monday, October 30, 2006 11:06 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: AMC format

 

Hello Gary,

 

We have done a few of these boards and the way we do the edge connector is
to build each finger as two pads. Referencing your diagram below the pads
that are on the left of each finger are a mechanical pad with no connection
but the pads on the right are a connected pad with the pin number.

 

As for the gold fingers a selective plating process was used.

 

Rgrds

 

Peter Hughes,

PCB Designer,

Concurrent Technologies,

4 Gilberd Close,

Newcomen Way,

Colchester,

Essex,

CO4 4WN.

Tel: +44 1206 752626

Fax: +44 1206 751116

-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Macindoe, Gary
Sent: 30 October 2006 16:41
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] AMC format

 

Hey guys,

 

I'm doing an Advanced Mezzanine Card (AMC) format design and have a few
questions.

 

This format has an edge connector on one end with a strange contact pattern.

As opposed to the normal (i.e. PCI) edge connector fingers (all the same),
this format has some two part fingers that connect sooner or later than
others (see diagram below).

 

My first question is about creating the pads/symbol for this edge connector:
as far as the two part padstack fingers (Second, Third & Last Mates), how
would you create them?

 

My second question is concerning gold plating this strange finger pattern.
It seems to me that the only way is "selective plating", as opposed to the
normal edge connector plating process, correct?

 

We're in a state of flux right now, not sure which fab house to ask, so I
thought I'd ping you guys.

Thanks for any responses!

 

 



 

Gary E. MacIndoe

PCB Design Engineer

Advanced Micro Devices

Longmont, Colorado

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