 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : Soldering SMDs
| Author | Message | ||||
James_From_Canb Senior Member  Joined: 19/06/2011 Location: AustraliaPosts: 265 |
I soldered a SMD crystal onto a board yesterday. What a pain! Wonky eyes, shakey hands and small components are a bad mix. Every time I moved the crystal body to be aligned with the solder pad, the two leads would move off their pads. I ended up soldering one of the leads and moving the crystal body so it bent the soldered lead. At least that held everything still so I could solder the remaining lead and the body. It took a very long time. But that got me thinking.... Posters have mentioned the problems of de-soldering SMD components that have been glued prior to soldering. Having tried soldering one, I can see why people use glue. Is there a glue that holds the component in place but melts after a couple of seconds with a hot soldering iron or heat gun? Also, is a Kester 951 flux pen suitable for SMD work? The blurb on ebay link looks good, but you expect ebay sellers to tell you that their product is the best in the world. Even the ebay sellers of water based flux give their products glowing reports. James My mind is aglow with whirling, transient nodes of thought careening through a cosmic vapor of invention. Hedley Lamarr, Blazing Saddles (1974) |
||||
CircuitGizmos Guru  Joined: 08/09/2011 Location: United StatesPosts: 1425 |
I have a Kester 951 pen and have used it. I actually prefer the Kester 2331-zx over the 951. I put a minuscule amount of solder on one pad, flux the heck out of it, place the component, touch the iron to the pad/component while holding it in place. That part/pad is then tacked in place. Solder the other pad, then go back and solder the first pad. Micromites and Maximites! - Beginning Maximite |
||||
| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
Hi James, I found it helps to manoeuvre the SMD with the point of a metal scribe rather than your finger. The ones about 20cm long and bent to 45 deg at the end work best. I also use the scribe to hold it in position (on centre top) to make the first solder tack. Not sure about which glue might melt for you - a silicone one maybe? Mick will probably know. Flux - I'm using a small 10g syringe of AIM NC254 Flux Gel from Jaycar (Cat No. NS 3039) which works well but it wasn't cheap, $20. It should last me forever though because I just put some on the end of a toothpick or match to apply it to the pads. There's got to be a good cheaper version though. The manufacturer's site of the AIM flux is www.chemtools.com.au Greg |
||||
bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
Hi Greg, Thanks for the vote of Confidence.. BUT!!!!!!!!! Whilst I have been soldering for nearly 40 years (And boy am I tired ... sorry I couldn't resist the old joke) I had never really tried much surface mount stuff till Geoff created the Maximite (yes I had dabbled but that was all) It was reading some articles on Geoffs site that gave me to confidence to give it a go and I found that it really wasnt as hard as I had imagined it would be.. If only I had started when I had eyes that could see what I was doing... I armed myself with some cheap liquid flux (off EBAY) and some solder wick and of course a good iron (A MUST HAVE if you wish to try it) Solder wick is good to remove solder from those pins that do get shorted together. The basic principal is to NOT apply too much heat... if it is taking a long time to solder a component STOP... Wait till it cools and clean off excess solder from the component and pads and start again. If it wasnt for my trusty USB microscope I would probably be in strife (with PIC chips certainly). Regards, Mick PS. Greg, I have Nick's CMM and whilst I have fixed the cap and broken track I tested the 3v3 supply and GND and there is a short there.. (5 Ohms) It is not the reg and there are only a few caps and coupled with Nicks statement that the PIC got HOT --- BLOODY HOT it looks like it has been cooked... I have sent the board off to my friend to de-solder the chip (many hand passes to get it there and many back) as I dont have the equipment to do it reliably and dont have it in my immediate future going to the workshop where the correct equipment is located. When I get it in my hands I will contact you if you are still interested in having a go... It is almost worth the trip to hold the `holy' board that was used to write/debug many of those games. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
||||
palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 1873 |
AS Geoff suggested early in the piece, I purchased a binocular microscope from the states ($120), and it's a completely different world. The scope has spring arms to keep the board in place and I made another spring loaded arm that sits on top of the component. I've been soldering for 55 yrs. I'm now 70, was having heaps of trouble with surface mount and now it is child's play. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
||||
Bill.b Senior Member Joined: 25/06/2011 Location: AustraliaPosts: 226 |
Hi Mick I find this a great help when checking my boards and soldering. 
http://dx.com/p/light-head-magnifying-glasses-with-4-pie ces-different-multiple-lens-3-aaa-51583"> Bill In the interests of the environment, this post has been constructed entirely from recycled electrons. |
||||
| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
@Bill, Yes, they are great. Downwind and I both use something similar - I don't find the head lamp much use though and prefer a back light and desk lamp. As far as flux goes, I used FRY's flux paste (like a grease) for decades until it got too crappy from dipping my iron tip in back in the copper tip days (remember the scope and mini scope and the solder gun?). All I use these days is zinc chloride and a cotton bud. Zinc chloride AKA Bakers soldering fluid. It might sound a bit fierce but it can be watered down. I have never had a problem with it. Most boards can be washed down with water and dried with a hair drier. I put sockets on after the job is washed and dried and the flux finished with. I used it to solder the PIC32 (TQFP 100) the other day and it went perfectly. That is just using a fine chisel point iron (temp controlled). David M. |
||||
| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
i've done a great deal of hand SMD work in commercial environments, down to 0402 sized resistors and capacitors as well as quad flat-packs onto multi-layer boards. this is a list of what i now always use: EREM 1-SA stainless antimagnetic tweezers BERGEON no. 4422 eyeglass Kester SP-44 rosin paste flux good quality solder, preferably with a small silver content Weller 'magnastat' fixed-temperature soldering iron, WTCPT/TC-201, with a 700 degree F medium tip similar (much cheaper) items from jaycar are: TH1754 Anti-Magnetic Precision Tweezers QM3515 Eye Magnifier the tweezers must be precision, sharp, and anti-magnetic. mine cost about $70, and were worth it. the jaycar ones are almost as good. the eyeglass fits in your eye like a monocle and is of low enough magnification such that you don't burn your nose. the iron holds it's heat well - there is little use in having an adjustable temperature and the "7" tips are perfect. NEVER use a "6", only use an "8" for lead-free, and keep away from long spindly tips. clean the tip frequently with a corrosive tip cleaner (multicore TTC1 or similar) and then wipe and re-tin. the SP-44 flux is no longer available (i have a couple of 2oz pots to last me), but many other rosin/petroleum jelly pastes are out there. type "rosin paste" into ebay. IC's are soldered by 'dragging' the solder over the pins, while resistors etc are soldered one end at a time while holding the part with the tweezers. use PLENTY of the flux - it works like magic. solder wick is used for cleaning up excess solder afterwards. again, don't scrimp on the solder wick. if a joint gets messy, add more flux and reflow. |
||||
| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2350 |
oh, forgot to mention - have PLENTY of light. like a couple of anglepoise lamps with the largest CFL lamps you can find 12" above your work. CFL is best as then you are less likely to burn the top of your head. |
||||
| James_From_Canb Senior Member Joined: 19/06/2011 Location: AustraliaPosts: 265 |
Thanks to all of you for the advice. Time to go shopping 
James My mind is aglow with whirling, transient nodes of thought careening through a cosmic vapor of invention. Hedley Lamarr, Blazing Saddles (1974) |
||||
| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Despite our age, some of us still have most of our hair.  David M. |
||||
| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
OK Mick, looking forward to holding the holy grail! BTW, my Atari joystick thing with the big red ball arrived a couple of days ago. It's pretty big but once I figure how to mount it I'll have a go at the top score - look out Nick! Hi Paul, Yes I bought the same one that Geoff mentions on his website, about a year or so ago. It's from Amscope in the USA and it's a major help. Cost around $130 but also $60 shipping  "Sharp Stereo Microscope Model SE303-PX (5X-10X-15X-30X)". You also need to tell them you want the 240V transformer "upgrade", another $15.
The temp controlled iron is mandatory - I've been using a 1.2mm wedge tip with it but I just recently received a 0.8mm wedge and I'll see how that goes. Robert's comment about lots of light is important too - you need it up close, the o'head light is nowhere near enough. The solder wick needs to be narrow too. I'm using 0.025" wide wick, about 1mm wide - I first tried some 3mm wick that I used for through hole work but it's way too big. Another help that's cheap and handy right now is those 360o, tilting, swivelling, suck-on bench top vices. Aldi has them right now for $15 - they're pretty good and sturdy and there's also a "G" clamp attachment version. Greg |
||||
MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
This is on my wishlist:
Reflow But currently i make do with a thick bottomed frying pan on an electric stove. 
It works actually pretty good! For handsoldering i have a temperature controlled soldering station and use a pretty large tip. I use the technique shown in this video starting at the 2:00 mark. I still looking for a USB microscope as i would like to view what i am doing very closeup on a big monitor. I have steady hands, eyesight is still good (at least for closeby) but i don't like to be that close to soldering as you would need protective glasses and a very good suction to get rid of the fumes. I check the soldering with a loupe. @Mick I would like to know how your setup is with a USB type microscopes and how you use it. Microblocks. Build with logic. |
||||
 Print this page |
