One good and easy test criteria for a solderless breadboard is how well it works with square post headers. A good quality breadboard works well with thin and thick conductors and has a long contact life. Good quality breadboards will be usable with fine 26 AWG wires or large 0.025" square post headers.
We've seen poor quality breadboards that are very cheap, and square post headers either cannot be inserted or cannot be removed once inserted.
We have several kit manufacturer customers that have switched to using BusBoard BB830 breadboards in their kits because they work reliably with square post headers. One customer tested 15 different brands of solderless breadboards to find one to sell with his development boards. He found that only two of the 15 brands were could be used reliably with square post headers and he now sells the BPS BB830 in his kits. We're proud to supply a high quality product.
Our factory performs quality testing on our breadboards by inserting a smooth 0.025" post 50,000 times with a machine, and then measuring the contact resistance. A good quality contact with the correct metal composition (phosphor bronze with plated nickel finish) will spring back and provide good contact force and conductivity even after a large number of insertions.
In summary, some criteria you can use to judge breadboards are:
- insertion force for 0.025" square post headers
- removal force for 0.025" square post headers
- good conductivity with 26 AWG wire (even after square post insertions)
- consistency, do all contacts on the breadboard work equally well
- consistency, does each batch from the factory work equally well (even months or years apart)
Although our breadboards are specified for use with 21 to 26 AWG wire, a conductivity test with 28 AWG or 30 AWG wire will reveal whether contacts have sufficiently good precision and holding force. Some poor breadboards won't grab a small wire.