24 of May 2018 , tonight , is electonics night!


(Andrea Campanella) #1

Who got a new member? @electrotechs !
Who is him? Is @electronoob !

Join us tonight from 19.30 pm for a social , skill sharing night about blinking LEDs and popping capacitors !


(electrotech) #2

thank you for the warm welcome <3


(Daniel Sikar) #3

Yay! Solder pump and reflow oven action thanks to @Courty, and @lewisss and @Jonty_Bottomley for help sorting out compressed air.

Components

Solder Paste Pump setup

Pick And Place setup - same :wink:

Baked

Assembly minus enclusure


(Andrea Campanella) #4

You got a freaking uCurrent!

…did you take it apart before turning it on?


(Dermot Jones) #5

You mean a teardown? He can do that now it’s assembled…


(Andrea Campanella) #6

It was supposed to be an eevblog joke :frowning:


(Dermot Jones) #7

Yep…my comment too!


(Niall Casey) #8

I’ve been missing these a lot (and the space in general) due to dad classes and upcoming parenthood, but I should be back soon!


(Andrea Campanella) #9

:grin:


(Niall Casey) #10

For certain definitions of “back” at least!


(Daniel Sikar) #11

Now assembling an arduino driven electronic load and still amazed how the smd components right themselves - and the solder paste smudges self clean!

20180601_005332


(Calum Nicoll) #12

Looks great! I am hoping to come in soon and try it soon with a batch of boards - any tips? Never used an oven/stencil before.

Will get some paste unless we have a lot as I have 50 boards to make.


(Daniel Sikar) #13

Thanks - there is plenty of paste, it doesn’t look like much in the syringe but does go a long way.
Tips:

  1. Close big compressor.
  2. Connect solder pump compressed air (blue plastic pipe) from solder paste pump to compressor in workshop where gun is connected (disconnect gun).
  3. Open workshop compressor leaving pressure towards lower end.
  4. Check solder paste pump is pressurised - gauge should be showing pressure, otherwise check for leaking air where gun was connected and/or open up workshop compressor a bit more.
  5. Find a practice PCB, stick it in the reflow oven, power up is at the back of unit, then press last button on right of front panel - this will run the standard profile that’s been used.
  6. When the temperature is 1/2 way up, press same button to switch off. Remove PCB - should be warm to the touch.
  7. Spread some flux on the pads - there is a flux syringe and dry flux pen in one labelled compartment, near the middle of the storage unit.
  8. Adjust solder paste pump pressure and vacuum (retraction) dials to suit - this will vary the blob size of each shot. Use foot pump dispenser for applying.
  9. Practice applying solder paste on the test PCB. Once you are happy with the quantities, apply to your PCB.
  10. There is no rush to place components - take your time. I had my first PCB waiting for over one hour for all components to be placed. By that time the paste was really runny but worked out ok in the end.
  11. Place PCB inside reflow oven on top of another PCB.
  12. Press last button on right and let profile run to the end - should take around 5 minutes and tends to smell a bit of burning.
  13. Let PCB in oven for a few minutes for solder and PCB to cool.

That’s it. Any questions ask. Good luck!


(Calum Nicoll) #14

Thanks this is really useful! To clarify - you only warm the test pcb to check the oven works - and you don’t need to warm all the others? Also - why the extra pcb on the bottom in step 11? Cheers!


(Daniel Sikar) #15

Thanks. PCB is warmed to facilitate solder paste adhesion - @Courty explained me that feature - plus many others! :wink:
So yes, it would be good to warm the others, I think at least so they are upwards of stone cold. The extra pcb on the bottom was another Courty tip, I don’t remember exactly what that was for, maybe to aid air flow and cooling.


(Paul Court) #16

I’m impressed @dsikar, you were listening , 10/10 !! :smile:

Yes, always warm the PCB’s (and ideally the paste syringe) to about body temp, this makes the paste stick to the board far better and activates the flux in the paste. if the board and/or paste is cold, the paste is stiff and doesn’t adhere very well + it makes component placement harder, you want the part to stick into the paste not sit on top of it or the parts will tombstone (sit up on one end) or wander off when you run the board through the oven.

Having the main board held off the metalwork of the draw makes the reflow more even. When the PCB is on the metal surface directly, you get hot and cold spots - I normally use a couple of pieces of scrap board, one at each end to lift the main board off the metal.

The combination of the air paste gun and upgraded oven works Really well and once you get the hang of it you can knock the boards out really fast in small batches production style

Courty