Thanks guys!
Nice shots Tom E let alone drivers. I admire your abilities.
Thanx! Not bad for a reflow station that consists of a coffee mug warmer and an embossing heat gun 
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I bought a similar embossing gun to yours when you first posted about it and have not looked back reflowing leds. I'll have to post up a picture later how its set up. How do you use yours?
It's not my idea btw... A friend of mine set me up with this stuff - he's an EE by trade, but sort of software engineer/super hobbyist - rockets, RC's, ham radios, etc. He's like a lot of us - just a big kid play'n with his toys .
What I do is get my mug warmer up to temp, sit the board with the solder paste and parts on there for like a minute to warm up, then go over it carefully, but keep the hot air gun moving, usually pretty close, an inch or two. The paste goes thru cycles - watery first, then dries out and hardens bit, then some bubbling and smoke is a good sign you are getting close, then finally we get liquid metal...
Usually things go well, but sometimes I get parts float'n around, blown off, and even had caps stand up on one end?? Weird things can happen...
That's called a "tombstoned" part. That happens when one pad heats up a lot faster than the other, like when you have a large ground plane on one side of the component and a thin trace on the other, and you haven't given time for the board's temperature to equalize. Pre-heating or heating more evenly across the entire board instead of focusing on a particular component generally eliminates this.
For the BLF17DD driver: whats the most suitable mosfet atm, as long as 70N02 isnt awailable anymore and Digikey EU shipping fee is 55$- anybody from Europe found a suitable solution?
Actualy there are Aliexpress offers for 70N02 and AOD510 but i aint sure in their quality
What do you think of this one
Sorry can't help - no clue there. I still have a few original 70N02's I'm using up slowly, though I've pretty much transitioned now to wight's A17HYBRID-S board, using the SIR800P FET - great design for it's low profile, single sided parts, high performance, and ability to run a single 7135 for low modes. Right now I'm using 5 modes with the first 3 out of the 7135 at PWM values of 4 (or 5), 30, and 255.
Mostly I consider this board obsoleted, but there still can be applications. Richard knows a whole lot more about this stuff, but he sells these FET's, and I would think they are excellent - his research for these was intense:
http://www.mtnelectronics.com/index.php?route=product/product&path=25&product_id=213
If you can't order them directly from Richard (shipping costs, etc.), I'd check for Euro sources of this exact part.
Tom, you mean 17mm DD+single-7135 driver ? Can it be controlled via an el switch? Thats the main reason i wanted to try this driver out
Well, i will test that MOSFET anyway, ordered a sample already
Yes, this: https://budgetlightforum.com/t/-/31102
I've built a couple with my custom e-switch firmware, based on the latest version from JohnnyC, STAR_Momentary (http://bazaar.launchpad.net/~toykeeper/flashlight-firmware/trunk/files/head:/JonnyC/STAR/STAR_momentary/). It has full support for the two PWM outputs. Recently modded a UF F35 e-switch light, a Yezl Y3, and now I'm working on a ZY-T11 clone. I got amazing #'s on the F35 and Y3 in a neutral tint, so expecting the same for the very pocketable ZY-T11 clone - it will have a MaxToch 25mm MCPCB screwed down, 20 AWG wires with the LED+ direct connected to the spring from the LED via holes drilled thru the stock driver (stripped) and hole drilled thru the LED+ pad on the HYBRID board. The ZY-T11 clones from BangGood is a great deal for what you getting, and really nice mod host. Like the lockout feature of the anodized thread tailcap, very compact size, nice size reflector for some throw, can take a big MCPCB, excellent reflector for wire soldering clearances, etc. The quality of the anodizing is fair (not good) and you play the lottery on what condition it will be in, but I lucked out on the 3 I've gotten.
I was sniffing around a bit and found Farnell:
http://bg.farnell.com/international-rectifier/irlr8721pbf/mosfet-n-d-pak/dp/1551907?ost=70N02&rpsku=STD70N02L
They seem to be shipping to many countries. And then there are also Mouser and Digikey. Those I think are the big international ones in electronics, from the west at least.
Lots of different FETs will work, with the most important factors being on-resistance at 3V-4V gate voltage and total gate charge. A good starting point is to look for a logic level FET with as low of on-resistance at 4.5V you can find, then go into the data sheet and look at the resistance vs. gate voltage figure.
Gate charge should only be a problem when you get up into the 80+nC range. Generally if you stick to FETs that are 30V or lower drain-source rated you will be well under 80nC, and probably under 50nC. The problem you run into with too much gate charge is that the attiny has a hard time switching it directly at fast PWM in the middle modes. If you do run into this problem, you can always put a gate resistor inline.
There are some "big" DPAK-2 FETs that perform slightly better than the IRFR3711ZTRPBF that I now stock, but the difference was slight and the cost increase was huge. Kind of like a PSMN3R0 vs. the SIR800DP: a tiny, almost imperceptible improvement, but at twice the price or more I don't think it's worth the cost.
Thanx Richard for the info!
Yes - I bought a dozen of the SIR800P's at $1.50 each, so I'm burning through them. It's hard to say what's worth 75 cents, and I'm not sure if I'll continue buying them. Putting it in perspective of what the total cost of a full mod is, it's certainly a small part of the typical $12-$24 (driver, LED/MCPCB, UCL or AR lens, materials, etc.). I lack the time and maybe expertise to setup a proper test bench for comparing these FET's, so I really appreciate your experience and knowledge on this.
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Some very important tools/rules (hope it helps and not too late):
- close-up work requires good magnified vision and good, strong lighting. A well lit room is not enough (from my experience).
- you need magnified vision to wear (I wear contacts that are horrible for close-up work, but using glasses on top of them that are built-in magnified - from drug stores, DX, etc..., it works well)
- I use a NiteCore HC50 headlamp for getting good lighting right where I need it
- you also need a stronger magnifier for close inspections of solder joints, solder flow, etc. Better if it has it's own light source.
- you need to carefully buzz out the board - pretty much all traces, before powering up the board first time
- any surface mounts that must be in the proper direction (diodes), you must be certain you have it positioned correct.
It's certainly not for everbody - I could never have done it on my own without professional help I got from guys at work who know wayyy more than I do (super tech, EE's, etc.).
Of course this list is only partial... Probably could add a dozen more things...
Thanks a lot for the help!
I used one of those cheap ebay loops, which helped me to see that one of the legs of one of the components was just hanging in the air... put solder on there, and now its working..pffff
For this kind of stuff I use a stereo microscope, nothing beats that in seeing what you are doing.
I have one of these oldies (Olympus zooming stereomicroscope) , but any type will do a fine job.
I use a $4 magnifying loop from FastTech (fasttech.com-rotatable-25mm-40x-magnifier). Can't find a link right now for the glasses, but think I use reading glasses in the range of 2.0 to 3.0. You can get them at drug stores ($10-$60) or cheaper ones online.
You can go cheap and still practical .
Bought a Radio Shack helping hands thingy a few months ago…. and NEVER USED IT!The glass is distorted bottle glass and the helping hands move about too much. P.O.S! Headlamp, aaa light, vice grip and a magnifying glass like what Tom linked to above are what I use. A needle nose tweezers are useful too but be careful! When a smd part pops out of those, they going flying off into oblivion!
Same here - I have a couple of those helping hands things and never used them. Can't figure it out, but same problems - mag glass is worthless and hands are too lose and unstable. I use a Harbor Freight desktop vice for just bout everything - with or without the rubber snap-ons, depending. The rubber snap-ons are now in real bad shape - too much distortions and damage from heating, filing, etc.