SMD component tombstoning during SMD repair with hot air rework.

[TVtechcellphone]

Hi everyone, I am still learning to do microsoldering but I am really old hats to electronic repair (had a full time job before that repairing TV and other electronics. Many of the electronics do have SMD repair but not BGA, SMT semiconductors (gullwing leads mostly) and SMD passives were larger.

Well, now I have to work with this at extremely smaller scale than before and lead free more tricky than before especially microsoldering, BGA is easy part. I have done both lead and lead-free soldering extensively for decades till now. Still have dislike for lead-free but you have to turn with the punch. Did use sufficient flux of good quality but still looking for tips and suggestions for better solder that is easier to deal with.

I know part of this usually the pad connected to ground plane stays colder while other pad to VCC plane warms up first and melts first causing passive component to tombstone using hot air rework.
I do have hot tweezers (small one, also do have larger one as well, new tips) also but still having not enough heat input to melt to put on but pads wouldn't melt easily or remove as easily. I do have PCB heater but this is for iphone circuit board size only and find this really useful.

Still, having problems with tombstoning. Any best tips? The solder we have is poor quality and is 1mm dia or bit less. Is there a really nice solder wire? I know this from electronics repair background a best solder wire is real moneymaker and pleasure to work with. For example SAC305 of good brand and multicore solder.

One more thing, is this really true that tips comes in two types, one for lead-free and other one for lead solders?

Reason for this is I wanted to know what is best out there and your tips is appreciated:

I was recently hired few weeks ago to do the micro-solder jobs and repair computer and cellphones, tablets, still learning the ropes on microsoldering. Well business provided me with their tools is Hakko model FM-203 station with soldering iron and hot tweezers and chinese brand hot air handle but pretty good for what can do with. I intend to invest myself better micro soldering station (JBC, Metalcal, or Thermaltronics or pretty best one, that can instantly melt solder on solder pad connected to the heaviest power planes?) to replace my failing Weller (they are expensive to repair and does not wear very well but works for most part but I really wanted something real nice this time.

Also another problem had to deal with this constantly with any Hakko tips (even new) tarnishing rapidly and easily and could not melt solder even with sufficient flux. Problem is from my experience this is too hot but no choice working with fine tips and working around where there is excessive heat sink. Another problem, I would have to tin the tip with solder but end up too much solder and hard to control soldering on the circuit board.

Tips?

Cheers,

[Jessa_the_Professa]

My advice is to put everything you know about soldering in a bucket and hang it on the door. This is a new industry, with new tools, and new scale. You seem to carry a LOT of baggage in your posts that are all "Well in the old days we used to xyz" Those days are over. Time to adapt! You'll be happier if you can just let yourself be a beginner. I know that is easier said than done.

To answer your question.

Hakko FM203 with FM2023 with T9I tips and FM2027 with BC2 tips are fantastic tools for working at this scale and are definitely perfectly suited to this work with practice. In my opinion, any other station is a waste of money for this work.

You likely also have the Quick861DW which is acceptable. It performs well and is not as sophisticated as the JBC but routinely outperforms and is preferred over Weller, Hakko, and Metcal rework stations by PBRS students. It is an excellent value.

Re: Solder. Use kester brand 63/37 solder for mobile device repair. No need for lead free. You will be mixing lead and lead-free. The body of research that leads people to think this is a bad thing does not apply to this scale and pitch.

This is what we use, and it is inexpensive to try: http://www.mendonipadrehab.com/suppl...ak/p/103755710
Tips last for months if they are tinned and wiped in brass wool, and the machine is set to sleep so that they are not on all the time.

[TVtechcellphone]

Sorry for rant, just bit anxious to prove myself at work, just got hired that all.

Taken together have been doing soldering since when was kid, had experience with SMD stuff before at previous work also, but not that much smaller than this so this is new experience. For sure, I do agree about lead and lead-free stuff are so drastically different. I have seen how easy to work with lead solder as long as they are quality kinds. I have SAC305 solder and does melt just right, and does not affect the soldering irons as badly. SAC means Sn, Ag and Cu which stands for Tin, Silver and Copper. 305 stands for industry standards type.

I'm not worried about dealing with BGA, it is the tombstoning that what gets me badly on passive components (inductors, capacitors and resistors, and fuses). What made this worse is no lead solder they have at work is subpar.

I recently had to redo the poorly crimped joints on connectors with solder on a custom power supply cable adapter to use standard ATX power supply on a HP Elitedesk 8300 motherboard at home.

My highest favorite is multicore brand and have ordered some samples from ebay for trial solders for quality envaluations. Two of them is Indium brand and small batch of SAC305 in .5mm size, There is Indium and AIM brands for solder paste as well to consider which is produced most carefully. MG Chemicals is one of major brand sells solder related stuff.

People who suggested very high soldering temp to deal with ultra-fine tip is kidding themselves. This leads to rapid tips tarnishing that I also have problem with and can burn off solder pads. But new problem comes up if you try to solder at 500 F and solder pads connected to heavy trace refuses to remelt unless board is warmed by the PCB heater.

I'll update on this later on once I get good solder stuff.

PS: if anyone can find silver containing lead solder, really works much nice too but could not find any in 0.5mm diameter size.

I know what Kester is, my late father had that stuff, solder and flux gel in his toolbox for decades and is DIYer around the house and vehicles.

Cheers,

[Jessa_the_Professa]

Yes, crappy solder is a deal breaker. Get any 63/37 leaded from any reputable maker and you'll be a lot happier.

[TVtechcellphone]

Finally solved with a wipe of leaded solder tipped solder iron on all the pads and some flux, SMD 01005 size stayed there and sat down perfectly when soldered with hot air.

Cannot believe how easy to rip off a plated on end of a 01005 resistor, in a pinch flip it over. Not to worry, I have seen upside down SMD resistors working fine.
BTW is 01005 is what the smallest SMD for capacitors and resistors used in iphone and other makes of cellphones?

Had to bring from home my 0.8mm radio shack silver bearing lead solder, this is one with BEST melt, make you think all the joints soldered looked like chromed metal, that how shiny they are. I had ran out of multicore brand years ago. Used to buy multicore solder rolls while taking a side trip to electronics store in Toronto, Canada.

Gonna find source to buy 0.5mm lead 60/40 or 63/37 solder spools, what are your favorite brands?

Cheers,

[TVtechcellphone]

Use 60/40 paste instead of solder wire.

[Jessa_the_Professa]

We find that solder paste is not suitable for work on iPhone logic boards, we use it for reballing only. We recommend “making puffy pillows” with leaded solder as the key to making any component solder on easily. We only use Kester brand 63/37 solder wire. We do not use 60/40

All the recommended supplies such as solder and Pete are available at iPad Rehab Supply at http://www.ipadrehab.com