Re: gEDA-user: Specification of Rotations for Auto Assembly

[John Griessen <john@xxxxxxxxxxxxxx>]

Rick Collins wrote:
  But I
> found a copy of IPC-7351 and it clearly says that for SOT and most other 
> IC parts, the original rotation is with pin 1 in the LOWER left.  That 
> is what FreePCB does in the library editor by default.

But not all people asking fabs to make boards do it the same, so they
nod yes, then verify for themselves.

> Are you telling me that EIA defined a different original rotation?  It 
> makes no sense to have two competing specs for something that should be 
> universal.  What is the EIA spec number?  The only related EIA spec I 
> can find is for the carrier tape.

That's what Tom Hauscherr mentioned talking about layout, LP Wizard
IPC and EIA on the 10th herein Austin.  EIA made a standard that noone would use
once and they were dropped for a while until they got specifying tape
and reel to do.  They do it differently.  Fabs don't count on any of it.
they figure out by looking if the tape is loaded rotated from the assembly drawing.

Mentor's LP Wizard is able to make libraries with IPC or EIA or one other standard
as you select.  They don't worry about the lack of agreement, they just give users
an option and lots of automation.

John


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