Main Site Documentation

Preparing, populating and Reflowing a rigid PCB


#1

I’ve just finished a short video on the steps you need to follow to prepare, solder paste, populate and reflow a small rigid PCB before being able to boot-load it and deploy the NETMF CLR.

It’s the board used in my Simon Says posts

https://www.ghielectronics.com/community/forum/topic?id=18189


#2

@ Jason - Hate to break it to ya but I think your paste has expired. How did you test the board for failures after you completed it? How do you know that the heat from the reflow process didn’t break any of the vias?


#3

Only the observant amongst viewers would have spotted that. It is just beyond its use by date, but actually not excessively used and still behaving very well; it’s stored in a cool place and given how much it costs it’ll be in use until it starts to fail me.

As far as testing is concerned, I just built a couple and given that they’re not too complex and are only connected to components that do things, testing wasn’t too difficult and everything worked great. In truth I could have done with a few test pads to check voltages, PWM outputs, etc, but space was at a premium.


#4

Hey Jason, here’s a handy tip for placing the parts in good time.

Print out a 1:1 image of the foot prints with the pads and then tape this to the desk. You don’t want it moving once the parts are laid down.

Now place all your parts on this and when you are done, apply the solder paste to the PCB and then just pick and place the parts from the print out. Saves a lot of time and prevents the solder paste drying out whilst you fumble with all the packages.

PS. Where did you get the paste mask from and what pricing for it? That can be the most expensive part in some cases.


#5

@ Dave McLaughlin - Thanks for the tip. I’ll certainly be giving it a go on my next build.

The mask came from http://www.smtstencil.co.uk . They cost £13.50 for a single A4 sheet with as much on it as you can fit. It’s 125um and perfect for what I need. Recommended by our favourite Kiwi and I’ve used them half a dozen times. They’re good and turn the job around in less than three days.


#6

@ Jason - And for folks in the US, there’s oshstencils.com. They’re inexpensive and easy to use (you can upload gerbers or just Eagle files). I think @ ianlee74 has used them, and I just placed my first order this week.


#7

@ devhammer - I’ve used oshstencils.com for all of my stencil needs and they have been great! Highly recommended if you are in the US. :clap:


#8

pcbpool (beta-layout) offers the mask for prototype boards. :clap:


#9

Thanks Jason. I’ll see what their shipping costs to Indonesia are as currently I can pay around US$130 per mask (mind you, that is stainless and mounted) so a lower cost alternative would be great for the small runs I do.