Other Things

Introduction

This is just a page of miscellaneous bits and pieces not directly related to the projects, but that may be useful to some people.

SMD Pick & Place Alternative

As much as I would like one, I can't afford a pick & place machine. So in its place I make these little 3D printed jigs that help with hand-placing small SMD components on PCBs.

I found it works pretty well, you can populate a board quite quickly once you get going. One of the big pluses is you can spin the board around to get best orientation for hand placement. And you don't knock other components off every time you add a new one.

The jig is simple to draw up and takes as little as 15mins to print, depending on the PCB size. It's not that well described in the video, but

• Use the table of x,y values in your eCAD program to work out the placement of components in your mCAD program.
• In your mCAD the trick is to make a symbol library of different packages, making sure the placement handle is in the same relative position as you eCAD thinks it is.
• Then you just add the symbols to your drawing according to the co-ordinate table.
• You have to experiment a bit to suit you printer, but in my case the holes/pits have to be one printer-nozzle-width bigger in x & y directions
• Print the jig at the best quality setting for your printer. I put three versions of the jig in the video in case someone else wants to improve the method ... if you do, please let me know.

Interesting bit starts at 9:25 if you are in a hurry. Also sound is a bit soft, turn that sucker up!

Toaster Oven Reflow Recipe

This recipe is a mixture of times & temperatures that I have found works very reliably.

It uses a toaster oven at 'toast' setting, ie full setting on both elements, and uses the middle shelf. Then ...

1. Preheat to 80C, place board(s)
2. Switch ON
3. @ 140C, switch OFF
4. @ 45sec, switch ON
5. @195C, switch OFF
6. @45sec, Open the door and fan to 100C

I've thought about modifying the oven to run automatically but there are some insurance/regulation issues, though I'm also thinking reprogramming one of those wifi wall switches which would get around those problems. In the meantime this works well enough for my needs.

There's a couple of cuts in the video for bevity, the full process is about 5 minutes.

The procedure results in quite a nice reflow curve looking like this.

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