More cornish buffers

[aballen]

I got started on some SMT stuff here
http://www.madbeanpedals.com/forum/index.php?topic=14527.0

I wanted to see if there was a better way to do this than soldering by hand.

Today I actually made a solder paste stencil, and I'm going to try reflowing a few.  I'm please as hell on the stencil, so I thought I would share.  I'll post more pictures as I progress through this build.

[wgc]

Awesome Alan! 

How thick?  How did you cut it? 

Usually a good idea to make the apertures a little smaller than the pads (90%ish). This helps create a better gasket to the pad and also accounts for squeeze out when the part is placed, so less solder balls during reflow.

[aballen]

I made it from a can of diet dr thunder so it's pretty thin.  I just etched it with muratic acid/hydrogen peroxide. 

The pads are actually a hair big.  I may make another mask I just have to figure out how to shrink the pads.

[wgc]

Awesome. You're looking for about 5 mil thick. Should work fine as is, but you'll see what I mean. I think there's a way to export the gerber and edit as vector

[aballen]

I really thought that after using the stencil there was not enough solder.

I decided to try reflowing anyway.

It actually turned out great.



Since I'm compelled to buy parts in lots of 10.  I have a few more to make.  My next attempt will be the remaining boards. 

Also can't say enough about this reflow controller.  I sponsored the kickstarter and and was fortunate enlightened to get an early unit as a tester.  Pretty much set and forget.

[wgc]

That looks fantastic!  If you look close, there are some solder balls hanging out.  In this case not much at all to worry about, and only mentioning since it will you help you with the next stencil. 

But the fillets otherwise look dead nuts, and the parts seem to have self balanced about as well as you could hope for. Really awesome!

Also, your layout is sweet!  (I just got my boards yesterday, took a slightly different spin.  Will post in another thread.)

Would love to hear more about the controller. Reflow in an oven is all about accounting for thermal mass to get the right ramp and dwell times.

[aballen]

There is a soak period, then it gets up to temp.  Works really well from what I can see

[Jean-Rock]

Great post !

[wgc]

There is a soak period, then it gets up to temp.  Works really well from what I can see

Sure, but the time/temp for each phase needs to be set based on mass, type of flux, solder alloy, etc 

For hobby stuff probably little or no concern in most cases, but still interested in how this controller manages it.

I'm guessing they have a few settings where it's kind of averaged out?

Anyway, this is great stuff!

[aballen]

It is programmable.  I believe it will hold three profiles and comes with two already set.  One for leaded another for no lead.  You can set the soak temp and time as well as the reflow temp and time so it seems pretty flexible.  I've only needed the default setting, but I'll be adding another profile for powder coating

[aballen]

I'm do e for the day, but in pleased as heck.  Reflow is so quick.  I'll have to get better with the stencils.  But it looks
Like I was good enough.   Should only get better from here.

[chuckbuick]

That stencil is sweet!  I never thought I needed a stencil for my boards but now I kinda think I do. 

[aballen]

There is a video online in how to make a stencil from a soda can.  Really worked well.

[chuckbuick]

There is a video online in how to make a stencil from a soda can.  Really worked well.

Thanks.  I'll check that out. 

[stevie1556]

That stencil is awesome! And the soldering looks great!

That Reflow controller, is that for an oven? At the moment I've got a small flat head screwdriver that I use to spoon some paste onto a pad, then use a hot air soldering gun. It's so hard to get the right amount of paste on each pad so I've thought about going the stencil route.