6502.org

As you do your layout and consider the socket-or-no-socket dichotomy, keep in mind my POC V1.2 unit runs at 20 MHz without being on the ragged edge. I have my doubts the little bit of extra inductance added by a socket will matter in your application—it obviously didn’t in mine.

One other thing in favor of using a socket is the ease at which a part can be removed without damage, should the need arise. That has allowed me to salvage “expensive” parts from older POC units for use in new ones.

(We've mentioned before that PCB technology keeps moving on: for example, four layer boards are now much more affordable. In the same vein, I gather assembly is now affordable from some suppliers: they will deliver assembled, or partially-assembled, boards, if the parts in question are in their catalogue. I think it's worth considering this option, especially when there's some anticipated difficulty with some surface mounted components. A board which already has PLCCs or RAMs soldered in, and perhaps also tiny capacitors, maybe even sockets, can then be finished off when it turns up.)

It is possible to hand solder SMT PLCC socket. With sufficient practice, the level of difficulty is comparable to hand soldering 0.5mm pitch QFP. I use a fine tip with 30 degree bend, Metcal STTC-026. The bend helps get around the plastic webbing of the SMT PLCC socket. SMT PLCC socket is bigger than PLCC IC, so you do need to allocate more space around a PLCC if you plan to use a socket.
SMT parts are generally cheaper and easier to obtain; pc boards with SMT parts are smaller thus faster & cheaper; and it is actually easier to solder SMT components than comparable through-hole parts once the soldering skill has developed. From cost point of view, if a designer is proficient with SMT soldering, I think an economical approach is to offer kits with SMT components already installed by the designer so the end users don't have to deal with SMT soldering.
Bill

What brand of PLCC sockets are you using? I was thinking of this kind, where the contacts are not accessible at all for a soldering iron, being completely underneath and covered:

The problem is the access, not the pitch.

Garth,
These are unusual SMT PLCC sockets. SMT socket's contacts should be visually inspect-able to check for proper solder joints. Photo shows my SMT PLCC44 socket on the right; the PLCC44 socket on the left is through-hole PLCC socket.

I'm getting there as far as struggling to see the tiny things. I'm jealous of the microscope camera I recently saw being used at this point in this video: https://youtu.be/nhAisp4dWq8?t=1054

I also found a PLCC-32 SMT socket that has mounting studs. This should make alignment much easier before hand-soldering one of these.

The mounting studs are nice alignment feature. The hard part about soldering the SMT PLCC socket by hand is not burning the central plastic webbing which is located very close the the soldering tabs.
Bill

I'd be tempted to take an X-acto knife and cut the little strands, then remove that little rectangular "floor" before the soldering even begins. Is the darn thing even necessary?

Alright, I guess maybe it's supposed to limit the depth of insertion of the PLCC into the socket. But you could wait until the soldering is done then put the little rectangle back where it belongs... secured to the PCB with a dab of adhesive. Hmmm...

-- Jeff

If your using a low temp solder paste the temperature should not affect the plastic.

Do you have side/angle shots that show how far the contacts extend below the bottom of the socket base?

I guess it's about the same as the stand-off height.