Using perfboard/protoboard/stripboard

[Aron Insinga]

I have a question about using perforated printed circuit board material, preferably with copper on it that wires or component pins can be soldered to.  I guess it applies to regular printed circuit boards too.

In particular, I’m wondering about the mechanical assembly of switches, jacks, etc. on such boards.

(1) You can get through-hole components that you can be easily inserted and soldered to the copper.

(2) You can get panel-mount components that you can easily mount in a hole drilled in a panel or a ‘project box’ and solder wires to the ‘solder lugs’ on the back of the component.  (a) You can run the wires to the board, insert them through a hole, and solder them to the copper.  (b) You can also solder the wires to a connector (e.g. pins) and plug it into another connector (e.g. a ‘header’) on the board  Either way, the panel can be mounted above the board, or the board can be mounted or in the box, with standoffs.  (The standoffs can be as simple as a long bolt with a nut on it, and a tube between the two surfaces to separate them.  I used to save the clear plastic hexagonal (on the outside) ‘barrels’ from Bic ball-point pens, after the ink had been used up, for this.)

I think it is clear that (1) is the typical solution for prototypes and some hobby projects, and (2) is the typical solution for production or more finished-looking hobby projects, or ones that may need to be rugged.

(3) Now the question: If you drill a hole in the board and mount a panel mount component in it, in this case it is a small toggle switch but I want more mechanical strength than I think (2) would provide, you can obviously solder wires to the solder lugs.  But what is the ‘best’ way to connect the wires to the board?

(A) You could run the wires around the edge of the board, but I think they would be too prone to snag on something.

(B) If you poke them through the hole from the bottom, with insulation stripped back so you can solder the wire to the copper on the bottom of the board, you can cut off the end of the wire sticking up above the board, but that just doesn’t seem very tidy.  I’ve never seen this done that I’ve noticed.

(C) Maybe you could bend the stripped end of the wire up 90 degrees for 1mm, then 180 degrees down for 1mm, then 90 degrees up for maybe 2mm to continue the original wire, insert the ‘bump’ into a hole from below and solder it.  I’ve never seen this done, I was just trying to come up with something between (B) and (D).

(D) You could just lay the stripped end of the wire flat on the copper and solder it down, maybe with a spot of glue to hold the wire in place while soldering.

(I have some old [ca. 1968] production hardware using a single-sided circuit board that had insulated wire stripped on the ends and soldered like this to create a jumper over another run, just to avoid drilling holes and putting a component on the other side.  It also had normal 14-pin DIPs with the pins splayed out flat and soldered to copper runs — primordial surface-mount technology!)

(E) If the insulated wire is thin enough, or the holes are big enough, or if you drill out a couple of holes to be larger, then you can run the insulated wire up through a hole and then poke the stripped end of the wire down through another hole and solder it.

For any of these, of course, the board needs feet, or standoffs above some base plate, to protect the underside of the components, not to mention the table under it.

So after typing this up, which made me think even more about it, I will guess that either (E) or (D) is the preferred solution for (3).

Regardless, I’m curious what others think, and what they’ve seen work well (or what they’ve seen that didn’t work well).  Thank you!

[Aron Insinga]

I found some information on the current-carrying capacity of stripboard tracks.  This person’s math says 5.4A, and more if you ‘tin’ the tracks (put a layer of solder over them).  Of course it is wise to put a lot less current through a track than the maximum.  Be careful.  I really have seen printed circuit boards from computers where the copper etch acted as a fuse and was blasted off of the circuit board!

https://electronics.stackexchange.com/questions/223702/what-is-the-current-carrying-capacity-of-a-single-stripboard-track

Raw data on the copper used on Veroboard:

http://pdfs.findtheneedle.co.uk/12420..pdf

http://www.farnell.com/datasheets/10822.pdf

Raw data on the copper used on a Velleman board:

https://www.vellemanusa.com/products/view/?id=524765

As for using wire, any recent edition of the ARRL Handbook has a table of wire gauges with the current carrying capacities.

[Aron Insinga]

FWIW, I here are a few things that are useful for running buses across perfboard:

(1) Something I’d forgotten about, Vector’s pins that can be inserted into holes in the board.  Some pins are meant for wire-wrapping, but others have holes in them through which you can run a bus (or other) wire.  This page has some nice pictures of the pins in use: http://lucianifamily.org/getting-it-done/assembly-hints/assembly-hints-index.html#breadboard-hints  (I wish they had included side and end views of the board too.)

(2) Narrow metal bus strips with holes every 0.1 inch.  I remember using these for wirewrap boards, but they could be used on perfboard too.  For example: https://www.newark.com/vector-electronics/t107-10/terminal-bus-strip/dp/90H9856

(3) Vertical dual-conductor “bus” strips with pairs of pins: https://www.electronicsurplus.com/unmarked-4-143-dual-bus-bar-9-l-0-10-x-0-50-spacing  (I haven’t seen these in actual use.)

 

[Aron Insinga]

I know there are solderless breadboards made of transparent plastic so that you can see the internal conductors, but has anyone ever seen perfboard or protoboard made from transparent or close to transparent translucent material?

I realize a lot of transparent plastic sheet material would be damaged by soldering temperatures, but fiberglass with no pigment added might be clear enough to see what’s on the other side of the board when doing something to one side, perhaps when working on a non-blindingly-bright light table.

I can’t be the first person who’s wanted to see both sides of the board at once.  I suppose a fallback, which might require more hand-eye coordination, would be a video camera pointed at the other side, or a mirror.  (Hmm, I should get a mirror anyway to see when someone is sneaking up behind me when I’m on the radio.)

 

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