Well… What are some hundreth of milligrams of lead compared to the quantity of alcohol, tobaccoe and sex I’ve had during my whole life ?
Joking aside, the oven needed some cleaning with pyrolysis, which I’ve done this morning. And btw, it has made a lot of smoke also because of some cheese and sauce that has previously spilled from dishes
Here I am waiting for stevepresley
I’m not in a hurry, though, because none of my existing boards really need a stencil. But now that I know I can use oven, I will design PCBs accordingly (and hence will need stencils).
In the meantime, I will create a “training PCB” with different footprints for some chips I have and I can “waste” : DRV8402 (HSSOP), TPIC2810 (SOIC), MAX5392, HC4511M (SOIC), PCA9554 (TSSOP) and even DRV8800 (QFN) !
Classic, you sure you don’t have a bit of Kiwi in you?
New Zealanders are famous for the quote “she’ll be right” and would probably use the kitchen oven as well
I will be trying my setup this week. I am going to order the stencil though. The pads are to small and judging by your experience it is really easy to bridge them. I will share my experience here.
From another test, here’s what I’ve noticed so far for this super-tiny pitch :
[ul]quantity of solder paste should be very (very) small, even on pads
the chip has to be correctly positionned at the first try or else any subsequent move could spread the paste between the pads, hence creating bridges during the melting phase
shaking hands, sneezes or Halloween jokes during this phase are strictly forbidden
it’s “easier” to put solder paste on the chip’s pins rather than on the PCB traces : even if you create a bridge between two pins with the solder paste, you can always use a small sewing pin to remove it
the temperature/time of soaking seems at least as important as for the melting. [/ul]
Again, this is targeted to this fine-pitch chip (HTSSOP48). Things are way easier with 1206 resistor
Also, I have a “boost” feature on my oven that helps the temparture to raise faster, which is fine for the melting sequence, where temperature should climb quickly (as per the different docs I’ve read).
For many applications no-clean flux works fine. It can cause problems on RF circuits (or clock circuits) though in high humidity conditions. Since the flux is still on the board it seems to absorbed the moisture and wreak havoc. At a place I used to work we had an issue with some boards during UL testing. It was tough to track it down as well as only a small percentage of boards would exhibit the problem. The last time I was down visiting them they had started building their own RF modules and switched to a water clean flux and had a really hi tech system to clean the boards…they placed the panelized boards in a dishwasher at the end of the production line.
For use at home the water clean is the way to go. You wind up needing to touch up a few things when you reflow a board at home anyhow, so the board will always need to be cleaned.
First attempt using the osPID controller worked really nicely.
Shame I got the most expensive part, the one with the really big concealed thermal pad, backwards. My rework skills and tools weren’t up to fixing it, so I’ll try a new board tonight!
Profile attached…
Any update on your method of madness when it comes to SMTs?
I’m starting to do some research on hot-air for a project that may involve some TSSOP-30 chips. I’m not confident in my drag soldering abilities at all.
