How to make a layout for a prototype?

When developing microcontroller firmware, you have to debug it on prototypes. The prototype is just a set of debug boards connected by jumpers.

Prototypes are especially relevant when the board of the combat device is still in development (production), and the software already needs to be developed and debugged somehow, then you have to assemble a prototype from a set of debug boards.

The fact is that we are not working here in zero gravity, and if we simply connect the boards with jumper wires, they will suddenly fall off under the action of a tension force.

Therefore, it is necessary to fix the boards hard on one common base and then only connect them with jumpers.

It is also often necessary to install on an expensive premium PCB board protective screenso that when transporting without a box in a backpack, the components on the board are not scratched, for example, with keys. Or it is trivial to protect the board from coffee accidentally spilled on the table.

I was surprised to learn that people have problems with the manufacture of such substrates (screens) for PCB prototypes.

What is the difficulty?

The point is that we need a lot high accuracy drilling holes (hundredths of a millimeter), and the position of the holes relative to each other can be simply random (s) like the position of a cluster of stars in the sky.

Therefore, it follows instruction how to make a quality base for a prototype.

What do you need from the equipment (hardware)?

Equipment	Purpose	category
plexiglass	To make a backing or shield	consumable
plastic racks	to bond the board and substrate	consumable
plastic nuts	to bond the board and substrate	consumable
plastic bolts	to bond the board and substrate	consumable
a printer	To print a drawing	tool
USB Flash(ka)	To download a drawing to the printer	tool
Kerner	For tapping funnels at the places of future drilling	tool
A4 paper	To print a drawing with marking of drilling places	consumable
Calipers	To take dimensions from the board	tool
Ruler	To check the drawing after printing	tool
Scotch	to stick the drawing on plexiglass	consumable
hand drill	for drilling holes	tool
Drill 2mm	pre-hole drilling	tool
Svelo 3mm	drill hole	tool
Drill 5mm	for chamfering	tool
Flat screwdriver 4mm	To screw the board stands and backing	tool

Why plexiglass? It transparent. You can always read the silkscreen of the board from the back through the glass and you do not need an endoscope for this.

What do you need from the software?

Program	Purpose
inkscape	To draw a drawing
pdf viewer	To view and check a drawing before printing

1–Draw a drawing in inkscape. Inkscape is a free and simple 2D drawing utility.

2–Print out the drawing in scale one to one (M 1:1). You may have to split A3 into two A4s. Be sure to check with a ruler after printing that the drawing is actually M 1: 1

3– Stick the drawing on the plexiglass. In this particular case, you need to add new holes to an existing substrate, so I had to stick the drawing on the back of the org glass.

4–And now a very responsible step. Gotta get a manual automatic center punch (automatic punch tool) and carefully prick the funnels in the places of future drilling.

5–Drill holes first with a thin drill (2mm). It is important. If you make a mistake, you can re-drill next to the same thin drill. Then we drill with the necessary 3mm drill. And make a chamfer with a 5mm drill. A chamfer is required so that the bolt enters at different angles.

6–Screw the boards onto the plastic standoffs with a flathead screwdriver.

This is how the Bluetooth speaker prototype turned out.

If you do not have all this equipment in your bedroom, then this is not a problem.

You can print the drawing, for example, in the same city printing house, they guarantee printing on a scale of M 1: 1.

The blank itself can be taken to the nearest shopping and entertainment center (SEC). As a rule, in the basements of the mall (shkek) there is a jewelry or shoe workshop and you can drill or saw off in plexiglass there. It will cost about 500 RUR and 2-3 weeks of waiting. However, you will have to print the drawing and paste it yourself beforehand.

Conclusion

Make beautiful prototypes on a Plexiglas substrate, it’s not hard at all.

Aircraft modellers even have a saying:

If the product is ugly, then it will not fly.

Therefore, the prototype should also look beautiful.