Clarifications about PCB assembly

Question

I just finished designing my PCB, I printed it and assembled it. Everything seems to be working fine after some tests. However, assembling the load cells and power cables was really complicated and not really clean.

If I were to ask a PCB manufacturer to assemble the PCB, would that mean they would also solder things like the load cells (who are on a load cell amplifier, not on the PCB itself) or would I still have to solder those myself?

If I were to create routes to holes (sorry if I'm not using the correct terminology here) that are connected to my load cells on my PCB would that work?

Or is it impossible because these are not surface mount components but through-hole?

this is the load cell amplifier.

I solder the load cells in the RED, BLK, WHT, GRN, YLW holes on the left. –

Image CC by 2.0, from https://www.sparkfun.com/products/13879

This is the PCB:

These are the connections:

Answer 1

If I were to ask a PCB manufacturer to assemble the PCB, would that mean they would also solder things like the load cells (who are on a load cell amplifier, not on the PCB itself) or would I still have to solder those myself?

Many PCBA manufacturing houses can do this kind of work. You would need to contact them to see what their capabilities are. Usually you need to generate some kind of documentation or wiring diagram to show them what wires need to be soldered on to the PCB. Typically the tooling charges would be high for this kind of thing and wouldn't make sense for just a few boards, but if it's work you don't want to do then the costs might make sense.

Wires need strain relief. Solder makes wires stiff, and the solder wicks up the end of the wires and makes it stiff and if the wires are moved they will crack and reduce conductivity or go completely open. So some kind of relief in the form of heatshrink or a connector (some crimped connectors avoid solder all together) or housing (plastic) that surrounds the wire and keeps it from moving.

If I were to create routes to holes (sorry if I'm not using the correct terminology here) that are connected to my load cells on my PCB would that work?

It appears that you have wires soldered into the same hole as 0.1" header. Usually you'd want to have the wires soldered to their own througholes as the wire works better when it's stripped and inserted through the throughole and then soldered.

Another thing that you may want to consider is using 0.1" jumper wire and using a breakout board (either purchased or made)

This would be an example of a PCB with an extension (The holes are not the same size, they probably would be for your setup.)

Answer 2

There is a spectrum of assembly houses. On the one end are PCB assembly only, on the other end is full electromechanical assembly including key turn assembly (they buy and store all the parts and PCBs), machining, parylene coating, injection molding of cases, cable routing, and testing services. Whatever you need done, an assembly house exists that can do it.

That being said, assembly houses are typically costly. For example, the ones we deal with charge 1000 USD for processing the documentation, programming the machines, and stencils. There is additional cost per PCB assembled, and testing. It's not uncommon for use to pay 2500 USD for solder assembly of ten PCBs or less, and that's with us supplying the kit (components and PCBs).