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File TXT or Gerber?

Printed From: PCB Libraries Forum
Category: Libraries
Forum Name: Altium
Forum Description:
URL: https://www.PCBLibraries.com/forum/forum_posts.asp?TID=362
Printed Date: 22 Nov 2024 at 10:13am


Topic: File TXT or Gerber?
Posted By: cencia
Subject: File TXT or Gerber?
Date Posted: 15 Jun 2012 at 3:41pm
Hi All,
 
I need to know how to create files (maybe from Gerbers) for machine for the positioning of SMD components.
 
Can you help me?
 
Thanks in advance,
Matteo


Replies:
Posted By: Artwork Master ITALY
Date Posted: 16 Jun 2012 at 2:00pm
With Gerber files you can usually see the copper layers of a PCB.
 
From these files it's not easy find the exact center of the components.
 
You can find them drawing an X from the limits of the SMD pads and from the center of the PTH pads.
 
A Lot of work indeed.
 
Good Luck

Posted By: cencia
Date Posted: 17 Jun 2012 at 1:12am
and what about Pick and Place file, in Fabbrication Outputs?

Posted By: Nightwish
Date Posted: 17 Jun 2012 at 4:27am
I am not sure what tool you use and in Mentor we can export a vb_ais file for SMT process and it is a .txt file.
 

Posted By: jameshead
Date Posted: 17 Jun 2012 at 6:38am
From most decent CAD systems you should have a report output facility and the programmers would have given you a pre-written report format for output of component x/y data.  This is usually in the form of a csv file and could be called component x/y or centroid data.

You need the bare minimum of component reference, x ordinate, y ordinate, rotation or theta, and side of board.  It's useful to have the footprint name and part number there as well though this can be in a separate BOM file which the assembler merges with the x/y position data.

If you've not provided this the assembler can create it themselves using the gerber data.  They would normally use an assembly drawing layer (component outline and component reference number) in addition to the solder paste (if creating for a SMT placement program) layer.  They can use the silkscreen but this can be more error prone.

Their CAM software is able to examine the solder paste and either assembly outlines or silkscreen outlines and do a kind of OCR to workout where the components are.  The assembly drawing layer is easier work from, can be more automated, and less prone to errors whereas if you've only provided a silkscreen to work from then there's more human interaction required on their part and they can make a mistake.

Although they can do this it is not the preferred solution.  The preferred solution is providing the centroid or x/y data in the csv file.


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