Home-made PCBs and vias

[josuah]

Hello tinkerers...

Do you have any suggestion for a better approach to vias than what I do (see below)?

I currently drill a hole, put a wire through, and solder the wire on the top and bottom layer, following the track.

It works reasonably well, but will not allow me to work with tracks under 0.5mm (currently doing 1mm).

Any suggestion?

I have just read about http://fab.cba.mit.edu/classes/863.16/doc/tutorials/PCB_Rivets/ on https://www.eevblog.com/forum/manufacture/cheap-source-for-0-6mm-via-rivets/

Maybe that is a more proper solution.

[jpanhalt]

I use wire, but I don't lap it as you show.  I use 24 awg wire, which is about 0.020" diameter, and a small carbide drill (#72 = 0.025,  #75 = 0.021).  Anything in that range will work.  The wire stays in by friction.  If that's not sufficient, then flatten one end a little, and it will stay.  Solder to the "annular ring" that surrounds pads and vias. 

Since 0.5 mm = 0.020", that method is not suitable for anything smaller.  Drilling much smaller holes and smaller wire is a possibility, but such holes can be hard to drill without a good set-up.

[sleemanj]

The easiest way for DIY vias... is not to have vias!  Embrace 0 Ohm surface mount resistors for short hops across a trace or two and 0 Ohm through hole resistors for longer hops, soldered top-side.

When it comes to actual vias, I have used rivets (0.8mm, aka eyelets), soldered both sides.  But... it's not cheap and honestly doesn't add much other than being a bit easier to insert (but even then, not that easy) and looking a bit cleaner on top maybe.

Wire sized for the via drill hole and solder is about as good as any.

Of course, it's 2022, you can get factory made boards for cheap and fast from China, with as many vias as you want :-)

[Whales]

Something I've thought of but I'm yet to try: fill the holes with conductive paint.  You'd probably have to paint both sides separately to ensure a good connection.  Likely still much faster overall?

[mag_therm]

Up to 30 MHz, mix of analog and digital, I can use single sided boards just by adding a few wire links.
This reduces the drilling.
I have some self imposed rules and methods:

Alway use board size 3000 by 2000 (inch).
-This allows use of one vacuuum jig for uv exposure.
-can get 4 boards from a 6 * 4 and 4 transparencies from one sheet
UV exposure is short, 75 second under intense uv lamp - which helps sharpness
Use only 1206 resistors - to allow a track to get through if necessary as sleeman mentioned.

Don't use TSSOP-14 - too difficult to solder (see lower left of photo)
For logic I now prefer the SN74AUP single gates per package in SOT23 5 or 6 pin
(See lower right of photo)

https://app.box.com/s/us5pjv7tmcmzwp5ldb81uv6bnzgszgcb
(Excuse the blur,can't get a tripod over that, as it is powered up)

[josuah]

24 awg wire, which is about 0.020" diameter, and a small carbide drill (#72 = 0.025,  #75 = 0.021).

Small drills and larger wire! That is what I need, I only have 0.030" drills.
Way to go for when I need a via!

Drilling much smaller holes

Some trouble that I observed from drilling is the tip of the drill bit vibrating and oscillating. I will consider shortening the other side of the drill bit to reduce vibrations and see how it goes.

0 Ohm surface mount resistors for short hops across a trace or two and 0 Ohm through hole resistors for longer hops

I would never thought about using an SMD component for the purpose of hopping around a track... That is great!

When it comes to actual vias, I have used rivets (0.8mm, aka eyelets), soldered both sides.  But... it's not cheap and honestly doesn't add much other than being a bit easier to insert (but even then, not that easy) and looking a bit cleaner on top maybe.

Wire sized for the via drill hole and solder is about as good as any.

Let's see how far I can go with all these advises

Of course, it's 2022, you can get factory made boards for cheap and fast from China, with as many vias as you want :-)

In my experience, it is more like cheap or fast, and the last FEDEX shipped one were marked as delivered while nothing ever came to my door at all.
I might have simply been unlucky.

fill the holes with conductive paint

I did not know about conductive paint! I definitely need some around.

just by adding a few wire links.
This reduces the drilling.

I see how the wires (red and bare), larger (like THT resistors) components can help me jump across a track...

As always, I may place the important and sensitive signals first, then use these hacks for connecting +3v3/+5v/GND/I2C_SDA/I2C_SCL...

This allows use of one vacuuum jig for uv exposure.

Using the poor man's approach of a acetone + toner transfer for now rather than photoresist. Not with best results I must say.
I keep the advises for when I finally switch over to UV marking.

Alway use board size 3000 by 2000 (inch).

Check! I am right on. (I assume 30.00 and 20.00)

Use only 1206 resistors - to allow a track to get through if necessary as sleeman mentioned.

Why did I even bother with 0603 for something below 30MHz to begin with...

Don't use TSSOP-14 - too difficult to solder (see lower left of photo)
For logic I now prefer the SN74AUP single gates per package in SOT23 5 or 6 pin
(See lower right of photo)

It looks like a key to making this happen is working with components that are comfortable enough to work (and rework) with.

https://app.box.com/s/us5pjv7tmcmzwp5ldb81uv6bnzgszgcb
(Excuse the blur,can't get a tripod over that, as it is powered up)

It is very fine, thank you a lot for sharing that picture.

[josuah]

Follow-up:
Cutting the base of the drill bit did help a lot with eliminating vibrations, I would recommend if you have spare drill bits.

[jpanhalt]

First, when I mention carbide PCB drills, they all have 1/8" shanks.  The actual length of drill for, say, a #72 is quite short.  There is no "vibration" of the tip.  What you see as vibration is probably runout caused by your drill press and/or chuck.

Trying to use a handheld drill with such small carbide wills would be challenging.

Spare bits?  Years ago, when ebay still had bargains, I bought at least 1000 solid carbide, resharpened bits from the Silicon Valley industry for about $0.012 per bit ($12 + free shipping).  I have enough to use them as toothpicks for hors d'oeuvres at parties.  They are a bit hard on teeth.

Seriously, with a decent drill press (mine is a 14" JET made in Japan) and good chuck, the only time I break a #72 is when I move the PCB before fully retracting the quill.  That is pretty infrequent.

[josuah]

First, when I mention carbide PCB drills, they all have 1/8" shanks.  The actual length of drill for, say, a #72 is quite short.
There is no "vibration" of the tip.  What you see as vibration is probably runout caused by your drill press and/or chuck.

I only need good drill then, they might be properly designed for it.  Thank you for the references.

I have enough to use them as toothpicks for hors d'oeuvres at parties.  They are a bit hard on teeth.

Now that's a good reuse for these sharp things! Everyone gets a free dental scaling.

Seriously, with a decent drill press (mine is a 14" JET made in Japan) and good chuck, the only time I break a #72 is when I move the PCB before fully retracting the quill.  That is pretty infrequent.

Maybe I was just having misalignment of the head on my dremel clone then.

[shapirus]

Not really worth it to open yet another DIY vias thread, so I'll go eco-friendly and reuse an old one.

Now, whereas actual vias are pretty straightforward -- just drill some holes, insert a wire with a closely matched diameter and solder it on both sides -- making holes for through hole components that sit flush against the board *and* must connect to traces on the component side, i.e., making the trace contact points hidden, is not so easy.

One way is to drill a slightly bigger hole to accomodate the component's pin and a piece of wire, then solder the wire on both sides, then insert the component and solder it too. I haven't tried this, and, while it sounds feasible, it also sounds very tedious and error prone.

Another way is to use rivets. There are brass rivets like this that come in different sizes:



They're available on Aliexpress.

I ordered some to try. The smallest size is 0.9 mm (the tube part) claimed, more like 0.95 mm actual, getting wider towards the flange, so probably will need 1 mm holes, but may as well be 0.9 mm, depending on how it will comply under pressure.

Inner diameter for the smallest ones is just above 0.5 mm.

Easy to solder, they're tinning very well (and solder is very easily sucked into the tube, which is both good and bad).

My plan, given that I don't have a tool to properly install them (to tighten and flatten on both sides), is to insert them from one side, press with something with a flat end (e.g. a drill bit) to flatten as far as it can go, then solder on that side. The other side can be soldered after the through hole component is inserted and cut just like a regular lead.

However, the flange diameter is relatively large: flange OD in the 0.9 mm rivets is 1.9 mm. While this is fine for vias (unless the board layout is very dense), it will not work, especially with the bigger rivets, for through hole components, unless they have widely spaced pins: for example, the 1.3 mm rivets have inner diameter just large enough for the 2.54 mm pitch pin headers, but at the same time their flange diameter is sufficient to short neighboring pins.

There is a workaround: the flange can be simply cut (using some good wire cutters) along the sides facing the adjacent pins, which will provide the required clearance. But this is also a somewhat tedious work, though it can be acceptable if the number of THT components that require such "plated holes" is low.

Has anyone found any better rivets or small tubes that would have really small flanges -- just large enough to prevent them from sliding into the holes? Aliexpress is notorious for poor search results relevance, so I may have simply missed something suitable.

[Whales]

Aliexpress is notorious for poor search results relevance, so I may have simply missed something suitable.

Sidenote: sorting your search results (eg from cheapest to most expensive) forces Aliexpress to only show things that actually match your search terms. 

Often you will notice that nothing relevant shows up for certain search terms, instead it's lots of items you have looked at recently.  If you then sort you will notice that it changes to say that nothing is available or only lists a few relevant items  

Years ago Alix search was so much better, it even let you specify the number of units you wanted to buy (!!!).  It has seriously enshittified since then.

[tooki]

Aliexpress is notorious for poor search results relevance, so I may have simply missed something suitable.

Sidenote: sorting your search results (eg from cheapest to most expensive) forces Aliexpress to only show things that actually match your search terms. 

Often you will notice that nothing relevant shows up for certain search terms, instead it's lots of items you have looked at recently.  If you then sort you will notice that it changes to say that nothing is available or only lists a few relevant items  

Years ago Alix search was so much better, it even let you specify the number of units you wanted to buy (!!!).  It has seriously enshittified since then.

I literally just discovered that workaround (sorting by anything other than "best match" or whatever the default is called) the other day!

Indeed, it seems their search has gone downhill lately. I truly do not understand this mentality of "show the user SOMETHING, ANYTHING at all cost" mentality, which affects both sellers (especially Chinese vendors, who stuff listings with irrelevant, imprecise keywords) and the platforms and search engines themselves, which seem to have decided that saying "sorry, nothing found" is an inexcusable sin. Neither of them seem to understand the value in being able to perform accurate searches.

[wraper]

Aliexpress is notorious for poor search results relevance, so I may have simply missed something suitable.

Sidenote: sorting your search results (eg from cheapest to most expensive) forces Aliexpress to only show things that actually match your search terms. 

Often you will notice that nothing relevant shows up for certain search terms, instead it's lots of items you have looked at recently.  If you then sort you will notice that it changes to say that nothing is available or only lists a few relevant items  

Years ago Alix search was so much better, it even let you specify the number of units you wanted to buy (!!!).  It has seriously enshittified since then.

Sorting somehow removes like 70%-100% of relevant results as well. I usually search in incognito mode, this way aliexpress pushes way less irrelevant garbage into search results.

[PlainName]

One way is to drill a slightly bigger hole to accomodate the component's pin and a piece of wire, then solder the wire on both sides, then insert the component and solder it too. I haven't tried this, and, while it sounds feasible, it also sounds very tedious and error prone.

Why is soldering the component pin on both sides not a decent workaround? After all, if the pin isn't in there the circuit isn't going to work anyway due to missing components, and if it is then the pin is as good as a wire. The only downside I notice (this is what I used to do) is where the component body might get in the way. For instance, screw connectors. But for those and similar I was always told to only route on the solder side anyway, so not actually an issue.

[DavidAlfa]

Something like this, only a small bend so it doesn't fall off when soldering. Not that huge extension you showed.



Found this in a NASA site (link):

[shapirus]

Why is soldering the component pin on both sides not a decent workaround?

It is, when you can. But there are cases when you can't: various terminals, relays, ZIF sockets (I'm doing this particular one now -- the testing polygon for the rivets), through hole electrolytic caps etc.

For instance, screw connectors. But for those and similar I was always told to only route on the solder side anyway, so not actually an issue.

It's not always possible to do it. Sometimes, when most of components are SMD, there is nothing except ground plane on the bottom side, and it's desired to route everything, including the THT connections, on the top side.

This is the ZIF socket for 2 x SOT-23-6 that I'm now making a breakout board for (to use with a solderless breadboard). Yes I didn't find a ready made one -- there are some with super big footprint and weird pinout (the respective pins of the two ICs are shorted), so I had to buy one of them and actually desolder the socket and create my own board.





There are 12 pins, which need to be routed to two sets (2 x 6 pin) of pin headers along the longer edges of the socket. I could not find a way to route all of them on one side (except for using jumper links which I didn't want to), so had to use both sides. The upper side's traces need to connect to the socket's pins where there is not possible to solder them directly (right under the body of the socket), so a DIY plated through hole has to be used.

Workarounds are fine where they are applicable, but sometimes you really need to use something that can serve as a PTH substitute.

[DavidAlfa]

Then it's pads, not vias

[KrudyZ]

0603 resistors are just the right size to bridge a standard 1.6 mm PCB THROUGH the board.
The need a through hole of around 0.9 mm diameter.
Use a 0 Ohm resistor to make vias or if the line actually needs a resistor then just put that through the hole.
For ease of assembly, these should be put in first by placing the bare PCB on a flat surface.
Insert the resistors where needed and solder from the top. Flip the board and solder from the other side.
Since the resistors are mechanically constrained, soldering is really easy and they also won't fall out when soldering the second side.
If you need finer pitch, i.e. smaller holes, then start with a thinner board, i.e. 1mm for 0402.

[shapirus]

0603 resistors are just the right size to bridge a standard 1.6 mm PCB THROUGH the board.
The need a through hole of around 0.9 mm diameter.
Use a 0 Ohm resistor to make vias or if the line actually needs a resistor then just put that through the hole.

Lol that's a nice one. I wonder if it's more or less elegant solution than a tight fitting copper wire...
I guess I'll order some zero ohm 0603 resistors just to have them in the kit.

Doesn't solve the PTH issue though.

[shapirus]

The smallest rivets mentioned above used as PTH:





Quite usable approach, the downside of course being that the flange has to be clipped.

Used a 1 mm drill bit (Chinese millimeters -- more like ~0.97 in reality), and it makes perfect holes for these 0.9 mm rivets: they slide in with a little bit of force, just the right amount. I put solder paste in and around the holes before putting them in, then flattened them and then heated the board with hot air to let the solder paste make joints where it would want to. Of course I ran a piece of wire through each of them before heating to clean the solder paste from inside.

[shapirus]

So I have tested these rivets in the role of vias... Nah. They work, yes, but the result looks ugly and it's just too much hassle to set them and solder in properly.

For PTH, yes, it's a good solution (except that the flanges have to be cut to make clearance where it's needed), quite usable. For vias, no, plain piece of wire soldered on both sides is better in every aspect.

[MathWizard]

Some old DMM's I've worked on made via's by rolling little strips of some copper alloy, into cylinder's with just a little overlap. IIRC, nothing extended out of the hole by any amount.

IDK if they were glued in at some point, but some of them came out when working on it with the soldering iron. Most of these had through hole parts in them tho, and they used them even if the trace was only on 1 side. They certainly worth my time to put back.

[Howardlong]

A related question...

How do you drill small holes (say, sub-0.6mm) without breaking the bits? Presumably there's some kind of precision pillar drill available that I've yet to come across.

[PlainName]

Use something with zero lateral play. CNC machine works ok

Also, very high speed (the tiny diameter means that the surface speed is really low unless you spin it at 20krpm and up) and don't push it in too hard - it is cutting slowly and doesn't have much strength against bowing.

[reboots]

Back when I was willing to make my own double-sided boards, I used brass "head pins" for jewelry making to populate vias. The pins have a very small flat head.



I tried a few different sources. Some pins vary too much in size and shape to use as the basis for a reliable design. Some have coatings which don't wet well with solder, since they are sold for appearance and not for electronics use. I recommend sourcing suitable pins, then measuring them carefully for via drill and annular ring dimensions to incorporate into your design.

A related question...

How do you drill small holes (say, sub-0.6mm) without breaking the bits? Presumably there's some kind of precision pillar drill available that I've yet to come across.

Doing this by hand requires an industrial precision drill press (sometimes called a "sensitive" drill press), or a purpose-built PCB drilling machine. Hobby drill presses have too much flex and vibration for carbide PCB drills. High-speed steel drills are easier to use, but dull quickly in fiberglass laminate.

I built my own inexpensive PCB drill press, as detailed below. The design had a few issues, but it was very successful with drills down to 0.25mm.

http://reboots.g-cipher.net/pcbdrill/index.html

Here is someone who mounted an air die grinder on a small industrial linear slide, for a compact, economical and successful solution.

https://www.instructables.com/%2430-High-Speed-PCB-Drill-Press/