Some more thoughts on a new morning: I appreciate all the suggestions on assembly tools, but believe me, I have them all. And the idea was to use powered, torque-settable tools for production. Those kind of tools are 100% no-go. Some areas don't even have enough depth for a manual ratcheting tool.
So, I went ahead and did a pros/cons breakdown of all of our options, and it came out something like this:
Option 1: Leave it as is and use manual tools when needed.
Pros:
- It's what we have
Cons:
- 15-20 minutes for assembly of one product would be typical
- Some products would not be assemblable due to soldering variation (canted parts, etc)
- Nightmare to disassemble and reassemble for service.
Conclusion: Hell no.
Option 2: Move all the parts to line up with heatsink wells and drill through, use screws and Nylocks through the heatsink.
Pros:
- It's a known solution (I've done this before)
Cons:
- Tons of parts (22 screws and 22 Nylocks per amp)
- Pain in the rear end to dissassemble
- Still may have some non-assemblable boards due to soldering variations
Conclusion: on reflection, it's not giving me warm and fuzzy feelings
Option 3: Add a stamped, spring steel retainer to apply even pressure to all of the devices.
Pros:
- Uses half the screws of Option 2, so it's faster to assemble
- We don't actually need to move anything on the board (!)
- Output device orientation is pretty much non-critical (everything can be assembled)
- Easy to disassemble
Cons:
- Unknown solution (I have not done this before)
Conclusion: this really seems like the way to go.
Why pick the more chancy option? Lots of reasons, but three primes:
- Although I haven't used this solution before, it is commonly used, so we are breaking no new engineering ground. I'm confident we can make it work.
- On a high-volume product, time for assembly and disassembly are critically important when you're paying first-world wages. This approach gives us that--and also reduces number of holes and simplifies the design of the thermal pad. It's a winner.
- We have a local metal stamping firm that I can literally walk to from our office and get things started on Monday. Even better, my other firm, Centric, has done marketing for them in the past, so we know each other.
Why a stamping? Because the heatsink has devices with three different heights: TO-247, TO-220, TO-126. This is necessary to use all the exotic 2SC/2SA parts that we've spec'd. But, because these devices have three different heights, we need more than a simple bar to tie them all down--the solution has to compensate for the different heights.
So, the $128,000 question is: does this affect the anticipated delivery date of End Q1? I'm not sure yet. If tooling the stamping doesn't take too long, maybe not. I'll keep you apprised as things move forward.
