Beginner pick and place example - Page 1
Forum section: electronics / general

author: OgreVorbis
author_rank: Newbie
timestamp: December 03, 2018, 11:26:09 pm
content: So I've been designing PCBs for a while, but this is my first time doing pick and place. I am having a surprisingly hard time finding a generic format for this type of file. It seems like most software packages all have somewhat different outputs. I'm using sprint layout and here are the options for the columns in the pick and place file:NumberIDValueLayerPosition (X / Y)RotationPackageCommentSo some of these are pretty clear, but there are a couple things I'm not sure about.It allows me to change the order. Is this the proper order of columns in a pick and place or should I rearrange them?In which column do I put the actual manufacturer part #?Does the value column have a specific format?The position has the origin in the upper left corner, but the example pick and places I could find seem to have it in the center. Does it matter?All in all, I'm kind of confused by the variability I see between different files I can find online. Is there no standard way to do it? I'd like to use whatever is the clearest for a generic Chinese fab.Thanks in advance.

author: SMTech
author_rank: Frequent Contributor
timestamp: December 04, 2018, 01:19:43 am
content: I have no idea what the purpose of the XY coordinate for pin1 or "upper left" it does seem quite common to be able to output it.However what you want is component centres and if you can't seem to do that, that could be because you have defined those packages that way.You could add an internal part number (and then reference multiple alternatives for that in the BOM) in the comment/description column, or add a part number column.The manufacturer will have tools to hand ranging from suites dedicated to setting up lines, the software on the machine or just good old excel, as long as they have the data they should be able to work with it.The software on my machine lets me choose which column contains what data, it can then create rules where it combines package & value to identify part numbers, but this can be dangerous if your value column isn't very accurate and the BOM has more specifics like a capacitor in multiple voltage but the same package.So I can handle:ID,Value,Package,X,Y,RotID,PartNumber,X,Y,RotSometimes I am supplied with ID,X,Y, Rot,Package and no part number, rather than manually adding the partnumber data on the machine I have a program that looks up each ID in the BOM file and copies the value/part number data across. This seems to be quite a common format so I presume some machines are setup to receive the data as two separate files.Arguably an actual part number is better than value+package as package often means footprint which might cover several packages, also CAD packages sometimes use very weird package names that mean nothing to anyone who hasn't seen them before.Some places using parts kitted by you might not even use part numbers, instead labelling the reels with a BOM line number and using that.As to formats, its all plain text CSV, although I would avoid using commas as they are quite common to find in both part numbers and value descriptors semi-colon or pipe seem quite safe tho' & if for some reason they don't like it.. that is what Excel is for. It seems to be a good idea to stay away from the newer Excel format however as some tools don't seem to like it still (whats it been 10 years?!)Once you have settled on a format, stick to it, on my setup I rely on a given client being consistent to let these automated tools build up their rules.

author: jmelson
author_rank: Super Contributor
timestamp: December 04, 2018, 09:13:16 pm
content: Quote from: OgreVorbis on December 03, 2018, 11:26:09 pmWell, those are the required fields.QuoteThere IS NO standard, although many CAD/CAM packages just have a standard output format, and the assembly houses know how to read those.Ask your assembly house what THEY want. Or, if using a standard CAD/CAM package, ask them what settings for the placement file they want you to use.Jon

author: mrpackethead
author_rank: Super Contributor
timestamp: December 05, 2018, 01:35:36 am
content: Quote from: jmelson on December 04, 2018, 09:13:16 pm^^ what he said. There is no 'generic' pcba either.