Silkscreen; board assembly

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Sam Wetterlin
Posts: 646
Joined: Sat Apr 28, 2018 6:48 pm

Silkscreen; board assembly

Post by Sam Wetterlin » Wed May 21, 2008 6:51 pm

Hi All

I thought a posted a message today but I may have hit Cancel instead

of Send. Or maybe it will show up as a duplicate of this.



We've been trying to see if it is feasible to add solder mask and

silkscreen to the boards while keeping them in ExpressPCB format, in

order to use ExpressPCB's full production service. If possible to do,

that would save time in converting the boards. As it turns out, there

would be a lot of effort in redoing the silkscreen layer, and there

would be some glitches in the way the solder mask and silkscreen would

come out. So it is likely necessary to convert to a different format,

obviously involving some delay for those who want silk-screening.



But here is something that should assist in assembly, and might enable

some of those desiring silkscreening to proceed without it. I have

created a folder in the Files section called Annotated Layouts, that

currently contains one ExpressPCB file. It is Scotty's PCB layout for

the PDM, with some added annotations. A line is brought out from each

component to the edge of the board, where the actual value of that

component is stated. This makes assembly much easier, as you don't

have to constantly search the board for Cxx, etc. I usually start with

the ICs, then grab a bunch of 0.1uf capacitors. Then scan around the

perimeter of the annotated board layout to see where they go. Then

move on to 0.01uf, etc.



I have done this with a number of boards and it was very helpful. You

still need to familiarize yourself with the parts list to get

organized, but during assembly the only document you need in front of

you is the annotated layout. I have had no problems with this method

locating the pads for the components.



Unfortunately, most of the boards for which I created layouts have

changed. But the PDM layout shows the current board. I think it would

be helpful if a group of people created such annotated layouts and

verified each others work, so others could rely on them. And don't

rely on my PDM layout unless/until you or someone verifies it.



Note: when you print these in ExpressPCB, the background area that

shows as black on the screen does not print. This means that if your

silkscreen layer is yellow, you will get the component values in pale

yellow on white paper. Very hard to read. So you have to use the

View-->Options menu, and then select the Color tab to change the color

of the silkscreen layer to something suitable. Black or dark orange

works for me. (That color setting becomes part of your program setup,

not part of the PCB file, so it does not transfer to others.)



Sam W.

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