So I’m building my first double sided drivers.
Some Texas Avengers in various sizes using the ATtiny 25 mcu.
I have a reflow hot plate, hot air rework station, and c245 and c210 irons with a good selection of tips for each.
I would assume you would flow the top side of the board on the hot plate first.
Would you then hand solder the extra 7135s to the bottom, or use hot air?
I’ve built about 5 single sided drivers, and used the hot plate for those.
What do y’all do?
I hand solder using a KU tip but I don’t have a hotair station.
Would hot air be a good application for the second side?
My concern was overheating the opposite side that was previously flowed.
It would be a lot easier, that’s for sure.
I have very little soldering experience, so I’m just bouncing ideas hoping one “sticks”. Could you secure all the finished stuff with Kapton tape or temporary/removable shrink wrapping?
I reflow the first side on a hot plate and do either hot air or iron on the second side depending on the complexity.
The only time I had a component (inductor) falling out on the other side I had pretty much overheated the entire board while experimenting with the station without using any flux ><
Yes hot air is fine, even if the upside down side reflows the components will stay in place, only heavy components can fall (like large inductors, electrolytic capacitors…etc)
Hot air for the second side using solder paste with lower melting point. The one I have is 138°C.
@Dc38 I had thought about similar methods. In the end I figured it would probably end up shifting components around when everything got hot.
@Pstool @thefreeman @Toaster79 Thanks for all your insight. I hadn’t thought about a lower melt solder for the second side. It seems like a good idea.
I ended up using hot air. It worked pretty good, I think.
For some reason, I thought it would be a good idea to attach the spring at the same time as the 7 - 7135s. That seems pretty stupid in hindsight. I kept knocking the spring around while heating the 7135s. Hence the extra solder on the center pad. Next time I will put the spring on last. FYI, I did the bypass led+ wire with an iron as the last step.
Now I just need to see if I get a working hex file going. My previous attempts in atmel studio 7 were fruitless. But I feel more confident today after some previous help from @INeedMoreLumens.
Wish me luck!
Nice job!
Are those new 7135’s? The solder points are clean!
I usually salvage the 7135’s and always get some bigger blobs on the pins.
Thanks @Pstool !
Yes, they are new. I got them from lcsc. I used 7x 380ma on the bottom and 1 350ma on the top.
I was trying to keep them as close to the center as possible. that way I had ample clearance for the retaining ring.
We will see how that goes.
I’m currently in a battle with Atmel studio trying to make a tripledown.hex file.
Is this a 20mm or 22mm board?
Try to avoid them at all or hit all of them, I don’t think it’s bad to have the contact on the tabs if the pressure is distributed.
I could even think on thermal benefits of this contact interface!
On the 17mm hue driver boards I use a retainer ring to align the chips as they try to float outwards, this gives me a really snug fit
It is a 20mm board. But I will be building 17mm and 22mm boards as well.
I had wondered about the thermal benefits of hitting all of the tabs as well. It seems to make sense you’d want to hit them.
That’s a great idea to use the retaining ring for alignment. I may give this a shot.
BTW, we have the exact same WEP Hotplate. It’s the perfect size for what we’re doing.
