Printing PCBs directly from National Semisoncudtor's datasheet

[Bricolo]

Has anyone tryed to make a PCB with the reference boards given in some NS datasheets?

I did it this afternoon, printing the top and bottom layer from the pdf, beeing careful to switch off the automatic resize, in order to print at 100% scale

Then, aligning the 2 sides, UV, revealing...

Back home, happy that the process worked well... I took my components and looked if the pads were correctly placed.

And...
The board isn't at the right scale! It's too small


2 double layer boards for nothing...

What's my error? I printed the boards at 100% scale, I don't understand.

[BrianGT]

I converted the actual gerber data to a pdf for you, if you print the pdf without scaling, it should work perfectly. There are also measurements on the layer to verify the dimensions.

I haven't used the files to make any boards. I simply downloaded the gerber files from NS, and used the free ViewMate 8.4 software to convert them (along with a print-to-pdf software package)

--
Brian

[Bricolo]

Hi Brian,

Thanks for helping, but it's for the LM4651 & LM4651, not for the LM4780

Here's the datasheet
http://www.national.com/ds.cgi/LM/LM4651.pdf


Try to print the page with the pcb, and look if the footprints are OK (the 4652 in the center of the PCB has the same package and footprint as a LM3875, so you can use this one to test)

[BrianGT]

Originally posted by Bricolo
Hi Brian,

Thanks for helping, but it's for the LM4651 & LM4651, not for the LM4780

Here's the datasheet
http://www.national.com/ds.cgi/LM/LM4651.pdf


Try to print the page with the pcb, and look if the footprints are OK (the 4652 in the center of the PCB has the same package and footprint as a LM3875, so you can use this one to test)

Alright, I just assumed it was the LM4780. Here is the top layer of the Class D LM4651 board:

--
Brian

[BrianGT]

Here is the bottom layer (file was to big to combine).

If I print it without scaling, it prints perfectly.

--
Brian

[Bricolo]

thanks, I'll try that

How did you convert it?
Does it also print to small directly from the datasheet?

[Bricolo]

Thank you Brian, your files are at the right scale

any idea why the ones from the datasheer aren't?

[Mr Evil]

Now you have learnt a valuable lesson: Physically lay out components on a printout before etching a PCB! That way you catch scaling errors like this, and in the case of newly designed layouts, you can catch any clearance problems that may not be obvious otherwise.

[Bricolo]

Yes, now I know

[jackinnj]

I believe that National put the Gerber files on their site -- it's a zipped file -- you can take the Gerber files and open them in a Gerber Viewer, then print from the Gerber Viewer -- you can print as a bit-mapped file. Pentalogix Viewmate is available as freeware.

btw, it's always a good idea to look over your PCB's with a Gerber viewer -- great at spotting things which your software forgets.