SMD Component Display Board

[parkview]

I have tried to describe to non-electronics people just how small some of the components can get, so I made up a bit of a display using cardstock:

SMD Display PCB - prototype_sml.jpg (14.95 KiB) Viewed 10409 times

The initial cardstock version was quite large, so I shrunk it all down to a 135mm x 30mm PCB. As it's larger than a 100mm wide PCB, it cost extra to have it made in China. I had Seeed produce it, as I liked their version of 'white' silkscreen colour.
Some companies use a greyish white.

It arrived today, so I had a go at soldering it all down. Apart from a few silkscreen errors, it kind of looks ok:

SMD Display PCB - ver 1.0 - top_sml.jpg (27.06 KiB) Viewed 10409 times

Luckily it doesn't matter if the components are shorted out by the solder. The solder is only there to hold the components in place. 01005 and 0201 are kind of fun holding them in place while soldering!

[parkview]

To solder the above PCB, I applied tiny amounts of solder paste via a tooth pick. It's not the most accurate method of applying solder paste, but it's OK fro low quantity items. I have been meaning to try out laser cutting some plastic Mylar solder stencils. I found a sheet of 1000mm x 600mm x 0.1mm thick (Mylar?) plastic sheet at the local stationary shop (now closed ). After aligning the laser cutter: http://forum.swmakers.org/viewtopic.php?f=4&t=221 I loaded up the LightBurn project file and some 54 seconds later I had a nice looking stencil raster scanned and cut out. All perfectly fitting the PCB.

What amazed me was the precision that the laser managed to cut out some 0.2mm x 0.4mm holes for the 00105 SMD resistor pads! I htink these are too small for solder paste to stick to the PCB. I have read that it's hard to stencil solder on 0201 and smaller component pads. I might have to do these by hand.

00105 - solder mask.jpg (9.42 KiB) Viewed 10392 times

Here is the 00105 pads being measured using a 0.1mm ruler:

0201 - silk mask.jpg (29.13 KiB) Viewed 10392 times

Lastly, here is a gigantic 2512 SMD resistor pad:

2512 - stencilmask.jpg (24.11 KiB) Viewed 10392 times

To prep the file before it was cut, I used the LightBurn to shrink the stencil border of the 0805 and larger components by 0.1mm:

lightburn - reducing mask border.jpg (26.06 KiB) Viewed 10392 times

Next weekend, I will try out the stencil, so more screenshots to follow...

[seaton]

Nice one Paul, Did you use cut or scan mode for the cutouts? The tests I've done int he past for SMD stencils I found scan mode the best.

[parkview]

I tried both and scan came out the best. The edge ridges are not too bad, ie: I think they wont cause any issues.