DBCstm, try hot plate reflowing. So much harder with a soldering iron, so easy with reflowing. Single burner hot plate, electric grill or griddle, you can find one for $10. Kitchen stove would work too of course but it not advisable with lead solder. Someone made a soldering iron reflow attachment. Small block of copper with a hole to take the whole soldering iron tip & a set screw to lock it on. He reflowed leds on it.
Definitely use more flux than is in the solder. Not sure on temp but I do 350-360 for smd, 375 and a larger tip on small mcpcb’s and 400 on 20mm copper.
That one must have been me, but the block is made of aluminium instead of copper, so that nothing sticks to it. I am just now heating it up to see if I can get the components off a 105C, not sure it will be hot enough to get through the board, the solder iron is build for 12V, I need already 10.7V for led reflowing, I have set it to 12 now.
New layout has a via in the middle of a processor SMT pad… not good…
ha!
so far so good :-)
go djozz, go djozz, go go go go 
Is this a functional “not good” or a Charlie the tuna “not good”? It alleviates other trace issues but it’s out here to improve it. Maybe put C1 on the other side of L- , ground it to the ring instead and move the via one diameter up and left?
solder paste on pads and placed the components, I could not have done it without my stereo microscope and Dumont tweezers (I inherited the tweezers from my lab job 12 years ago. If you ever think cheap tweezers are good enough for the job, spend 20 dollars on Dumont tweezers and be happy for the rest of your life)
Wish me luck!
Looking good there :party:
:nerd_face: watching, waiting, hoping.
Those components look new! Love it! Now, once you get this side re-flowed, you’ll just iron solder the other side?
Edit: I could do a hot plate, like I do the re-flows for LED’s. What temperature would be best? I can stabilize it using the IR gun and then place the board. When I do LED’s I put the switch on 4.5 or so and place the board from the get-go, watch it like a hawk and when the solder flows I remove it to a 3x3x3 cube of aluminum. I think 4.5 on the switch is too hot, as it will darken and smoke a star if left on for a few seconds too long.
My plate is 1/8” thick 316 SS, 6” in diameter that fits the smooth surface burner just perfectly. It’s a dull finish, but I’d need to figure out the emissivity setting for the IR gun to be accurate.
Get rid of that long trace between C1 and R2… connect C1 to the outer ring via a short trace… C1 will be MUCH more effective that way. Mpve the traces under the processor to the left. Shuffle the LED+ hole up and to the left some, should feee up space to get that via off the SMD pad (where it takes up a lot of space where the processor pin should be.
Would also be nice to find a way to get that trace out from between the two processor pins… makes life easier for soldering klutzes.
Yes, I do not have a neat way to reflow the other side as well. The reflow of the first side looks good :-) :
now the hand soldering part..
Rufusbduck, I’m looking to move D1 towards the LED+ via. Near the U2 silkscreen. The pwm via might need to scooch in under the pad a bit. Low on space for much stacking.
djozz, nicely done. Love solder paste. So it was you with the soldering iron reflow attachment! :bigsmile:
I think rules need to bent a bit here. Considering its a hobby project on a tiny board and they are looking to give clearance for people who might hand solder it.
This looks great and I’ve read about it but it seems like the heat has to migrate through the chips to get to the solder unlike an iron which applies the heat directly to the pad.
Beautifully done djozz! Very professional.
Another thing that you might want to do is extend the ground rings so their outside edges are a little past the board outline. That way when they cut the board, the ground ring will extend to the edge of the board and will make contact with the flashlight body.
> I don’t expect a huge demand
Changed your mind about that yet? (grin)
Watching, eagerly
That makes sense. In Solitaires it doesn’t work out that way because you don’t want the ground to inadvertently touch the body but in a AAA Minimag it’s different and it’s much better to file the ring off a bit when you don’t want it than to have to add it back when it’s not there. I’m also hoping we can find a way to enlarge one or two of the ground vias if a remote ground ring is needed.
Helios, I though you wanted it to go the other direction. Since your reversed 7135 is upside down the D1 via could stay where it is and just move the pads around the end of U2. Edit The U2 input via doesn’t need to go into the pad but just rotate counterclockwise into the space vacated by D1. If C2 moves left as above and C2-pin4 trace is eliminated then both R2-pin7 and R1-pin 8 can shift enough to put the U2 input via completely under both U1 and U2. I’ll have to verify that it still meets my placement restrictions though.
There’s just enough room if U2 is shifted toward Attiny silkscreen .4mm and the diode is right up against it. I’d rather not move C1 as it squeezes it between two things it cannot touch. Right now one end can physically touch the IC pin no worries but not so on the other side in which case it’s a matter of whether the ground trace under U1 can be traded for the ground ring. We’ve spent some time here trying to make this as easy as possible to solder. I don’t want to jeopardize that. Time enough yet.