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Apologies if this has been asked before - I'm new to the field, and to Stackexchange EE - so route me to relevant posts if some exist.

I'm aiming to order PCB assembly from a manufacturer (i.e. both PCB making and component placement). The board I'm using is two-sided, with components on both sides. So far, I've been making PCBs by hand, and connected the two sides simply by soldering a wire through a hole onto pads in both sides. However, I don't recon they will do this in an automated process, so I need to choose a proper via. Unfortunately, I have zero experience with vias, so I don't which to choose/where to look for a suitable one. So how to choose vias for automated PCB component placement process?

The board is 15 x 31mm in size, with the pads currently being 1.4mm in diameter, and holes being 0.4mm (or bigger) in diameter (see images attached). Although they can be flexible. The board is .4mm thick. Any suggestions, and if so why?

Top side Bottom side

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    \$\begingroup\$ Typically this is done with electroplating, at the same time as the rest of the PCB; they coat the inside of the entire hole with metal. So you don't really buy the vias. But another alternative is to use metal rivets sized to fit the hole. And a solder bump on either side \$\endgroup\$
    – jbord39
    Commented Jul 22, 2016 at 18:27
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    \$\begingroup\$ As @jbord39 said, you just need to specify that all holes are "plated through". \$\endgroup\$
    – Mark
    Commented Jul 22, 2016 at 19:46

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Holes on commercially made boards are usually plated through (unless you explicitly specify them as not plated). So there is no need to solder wires or pins through the board.

Since it's a plating process and not a pin the exact size doesn't matter too much. The sizes you are using now are perfectly fine (though if you need the space you could go considerablly smaller).

Some bargin basement PCB facilities have a list of standard drill sizes and charge extra for using other sizes but this is the exception not the rule.

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  • \$\begingroup\$ Important information here. Find out what the standard sizes are at your board fab and use those, alternative is delays, approximations or additional charges. \$\endgroup\$
    – KalleMP
    Commented Jul 22, 2016 at 22:05
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    \$\begingroup\$ I've found the standard sizes thing to be an issue only with bargin basement manufacturers. Another gotcha is that proffesional PCB manufacuterers work on finished hole size but some bargin basement facilities (and our in-house facility) work on drill size. Often the difference between drill size and finished hole size can be the difference between a component fitting nicely and having to force it in with a hammer or vice. \$\endgroup\$
    – Peter Green
    Commented Jul 22, 2016 at 22:16

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