[sdiy] Front panel and PCB design tactics

[rsdio at audiobanshee.com]

Ok, I'm going to stop adding to the "Front panel design philosophies" thread because I'm also focused on manufacturability.

Thanks for the numbers, Laurie. I'm currently looking at 12.7mm spacing, so hearing that you only drop to 15mm is useful to hear. Looking through the Doepfer catalog, I'm left with the impression that there is a wide range of styles from rather compact to generous spacing.

One big thing for me is to avoid soldering individual wires to the panel. I'd like to have PCB mounted hardware that screws to the front plate, and then nothing would be panel mounted in the traditional sense. Ideally, I'd like everything on the PCB to be surface mount, so that the whole assembly process can be automated without wave soldering in addition to the reflow oven.

Unfortunately, I think that I might be headed down a dead-end alley, because the first 3.5mm SMD jacks that I found have no threading. I'd need some other way to mount the PCB to the front panel. I'll keep looking, but I have a hunch that I'll have to go to through-hole, for the panel mounted hardware at least, in order to get threaded jacks (and eventually pots).

Anyone have advice, pro or con, re 100% SMD? I plan on using SOIC parts so that troubleshooting with a meter is as easy as with DIP.

At this point, I may still need to do more research on the costs of mixing SMD and through-hole, versus the simpler SMD-only. It's certainly trickier to deal with reflow soldering as well as wave soldering, and I suspect it does add to the cost. I already know that placing parts on both sides of the board - despite the benefits of bypass caps being as close as possible to the power pins - is way more expensive than single-sided.

Any comments welcome. I will say up front, though, that I do not subscribe to any belief that through-hole electronics perform better than the same parts in SMD. There are as many disadvantages to through-hole in terms of PCB impedances as there are to SMD in terms of unexpected capacitances. But apart from the potential religious batter between through-hole and SMD, which I prefer to avoid, it would be interesting to hear the costs to various assembly options including mixed and pure.

Brian Willoughby
Sound Consulting