Soldering many wires to small groundpoint

[Charkel]

Hello everyone!

I am pretty new to electronics and playing around with some Arduino HID projects. Now I have to solder like 14 wires to their respecive pin but there is only one or two ground points on the chip.
Is there any trick to soldering a lot of wires to a small ground point? Twinning them together will make a too big of a copper mass to solder on very good.

What's the trick?  Sould I connect the ground with one wire to a blank prototype board and wire in everything together on there?
When I have it on my breadboard there is a long rail so it's so easy but now when it's time to install it in the case I do not wanna use a breadboard

[ciccio]

You must solder all 14 wires plus one together, as shown in first image, then cover the joint with heat shrink tubing or some good electrical tape. The added (15th) wire will be the common ground wire.
Google for "soldering wires": you'll find a lot of tricks.
Best regards

[pigrew]

This is a common issue with most microprocessor development boards. Optimally, one would want the board to contain a ground pin for every I/O pin. But, with a limited number of GND pins, there is no great way to connect the grounds to the board, especially not with high frequency signals (> 1 MHz, perhaps). This is a very common issue for microprocessor dev boards.

If your connections are going from one board to another, you could get away with a single ground wire between the boards. However, if you actually need so many connections, you'll have to join them together somehow. As already suggested, soldering is an acceptable solution (where there is minimal vibration. vibration can lead to wires breaking.). You may want to look into terminal strips as your interconnect which would look more professional and be more reliable. Using (crimpable) butt splices, you can also crimp multiple wires together.

The best solution may be to make a custom PCB which does the connections for you (A protoboard could work, too). This would provide the best signal integrity.

[KL27x]

Your idea is how I would do it. I assume you are deadbug wiring it. I might glue the chip to a small piece of copper clad. Any twisted pair signals, you can solder the ground wire right next to its input pin. Also buy some 30 AWG kynar wire. You do not need big 26 to 24 AWG wire to carry 99% of your signals.

If they are simply unused pins, i just set them to output low and leave them unconnected.

[Ian.M]

No dead-bugging.  The O.P said Arduino - so at worst they're plugging into a female header and at best, are soldering to a row of 0.1" pitch pads at the board edge.

Assuming a DIL footprint Arduino board, its probably worth installing the supplied pin headers and soldering the module down on protoboard, preferably Tripad, but you could use matrix board at a pinch.  You can easily run a solid tinned bare copper wire as a bus bar along a row of holes a few rows away from the module edge on each side and link it to the Gnd pin as directly as possible to get an accessible ground pad for each individual ground wire next to its associated I/O pin pad.     Improve signal integrity with a 0.1uF ceramic decoupling cap from the module's 5V pin to your external ground bus.   If its really critical, run copper braid from the USB connector shell to the ground bus on both sides.

Piggybacking the module on a protoboard also gives you the option to drill proper mounting holes in the protoboard . . .

[paulca]

You get Arduino boards with this considered:
https://www.ebay.co.uk/itm/New-Pro-Mini-ATmega328-3-3V-8M-5V-16M-Board-Compatible-For-Arduino-Nano-3-0-UK/152355285956?hash=item2379152bc4:m:mr1N3rUDFrn1Wx-VtrKmntw

[KL27x]

No dead-bugging.  The O.P said Arduino - so at worst they're plugging into a female header and at best, are soldering to a row of 0.1" pitch pads at the board edge.

That is even better. This is where I would use 0.007" thick single sided copper clad and carpet tape. Stick the carpet tape to the back of the copper clad, then cut a thin strip of it with scissors. Peel the backing and stick it down next to the row of I/O breakout pads. In the arduino linked above, for instance, where it looks like they have 3 rows of pads for each pin, you could cover 1 or 2 rows of redundant pads. IC bodies are also a good place to add copper clad when you need some extra circuitry or soldering area.

If I want to really do some intricate soldering I have dipped the copper clad in acid, rinsed it in water, and let it passively air dry until it is black with an oxide coating. Cut crude pads/traces as needed with an engraving tool. The oxide coating means I have to scratch/scrape the spots where I want the solder to stick, so even if my traces are crude as cutting one or two lines in the copper, I can make the solder stick only to the SMD component pads/pin and/or jumper wires in neat little beads. This might be useful if you were say attaching many twisted pairs to your Arduino I/O. Just make little dots in the copper with diamond ball engraving tool for each connection to the solid ground plane, so you don't end up with big blobs which make it hard to get the wires on there without making others fall off.

Here's an example, collecting dust in one of my breadboards.
[Imgur](

)

[Ian.M]

Err ... the board Paulca linked to already HAS power and ground in the headers next to each I/O pin - that's why they are colour coded!   I still maintain there's no place in this project for dead-bugging though you might be able to argue the case for plonking the DIL footprint Arduino down  on some 3M VHB tape on a copper clad board and using Manhattan island construction.

[ebastler]

What's the trick?  Sould I connect the ground with one wire to a blank prototype board and wire in everything together on there?
When I have it on my breadboard there is a long rail so it's so easy but now when it's time to install it in the case I do not wanna use a breadboard

I assume you want to connect various peripherals (multiple switches maybe?) to the header of a regular Arduino board? The cleanest solution, in my opinion, is indeed to use a piece of prototype board.

Either use a board the full size of the Arduino -- which would give you room for some screw terminals, if you prefer a removable connection, or for status LEDs or such.

Or just use a narrow strip of perfboard, as long as the pin header and two or three 0.1" rows wide. Then solder a ground wire to the perfboard, which runs parallel to the pin header and connects all PCB pads in a free row (but does not block the though-holes). Connect your various ground lines there.

(Note that one of the pin-header rows on the Arduino is split in the middle, with a non-standard pin separation. An annoying design oversight in the original Arduino, and carried forward since then for compatibility. Either use only half of this header row, or use two separate strips of pins, and separate small PCB strips.)

[KL27x]

Err ... the board Paulca linked to already HAS power and ground in the headers next to each I/O pin

Err... I didn't look up the specs of the pictured board.

OP obviously using something else if he needs more groundpoints or plane. I described two ways to do that on just about anything. And Arduino doesn't necessarily mean he isn't using a bare chip/dead-bug, does it? I thought Arduino was the...

I'm not sure how to distill what Arduino is, to be honest, lol. Some form of free mutated version of C compiler with a predesignated/default configuration setup for specific AVR's to maintain compatibility of libraries and hardware? Oh... also it has the proprietary bootloader involved.

But please continue to tell the rest of us what the OP needs based on the limited info in his post and lack of any following. 

[Ian.M]

IMHO Arduino, without other qualifiers usually implies an Arduino.cc or clone board.   If its not in the current IDE's native board list or is a closeish clone of one that is, its at best Arduino-compatible.  If you are coding Arduino-style for a 'naked' AVR you aren't using an Arduino, you are using the Arduino toolchain.

The O.P's mention of "... playing around with some Arduino HID projects" and "... I have it on my breadboard ..." implies that he is using a DIL format Arduino board, as there are no AVRs in PDIP with hardware USB interfaces.   If he was using bit-banged soft USB like V-USB on a DIP AVR, IMHO, he'd probably mention it.