Solder joint removal technique / guidance request

[Simon S]

Replacing si batteries in a late model.

I’ve been soldering wire connections for stereo installations and motorcycle projects for years with a 40-watt iron.

Just returned from RadioShack with a 15-watt soldering iron to use for si battery replacement. I’ve never reflowed a joint or done worked on something this delicate before.

What technique should I use to separate the old batteries from their terminals?

Apply iron pencil tip to ‘outside’ of tang to heat the solder on connection side – while using a pick to pry the tang away when the heated solder allows separation?

Slowly poke/hold iron tip between battery end and connection tang for separation?

Since the iron is new, should I leave it naked/uncoated with solder when doing this?


Thanks for any help/guidance in this procedure – (first timer)

[bataangpinoy]

yes to your removal method, but get something thats going to get really hot. that way, as soon as you touch the joint, it come off and minimizes heat soak of the surrounding components.

[nando]

go to radio shack and buy a $10 solder sucker tool. it's a plastic tube/pencil shaped thing.

also, you'll want to tin the tip of your soldering iron first. google it. :)

[bataangpinoy]

ha i completely forgot that thing existed. i think he knows how to do it, but op just wants guidance on working with the delicate electronics. always tin the tip, and let the tip get really hot so that the solder joint melts almost instantly.

[Simon S]

I'm having trouble..
Here's what has been done:


First – I needed to slice out the rest of the amber-colored, anti-vibration glue from between the batteries.

The smaller piece was slid from its terminal to allow greater access to batteries.


Found more adhesive to slice out from between one battery and its relation to the larger, black, spade pin terminal.


I’ve been letting the tinned iron warm up for five+ minutes – then applying iron while gently prying on the tang with a metal pick. It took a while, but eventually, I got the positive-side tangs to come off. The positive ends of the batteries had a bump that stuck out. Negative ends were flat. The positive-side bump allowed for the pick to get under the tang for leverage.




Is the 15-watt iron weak for this job?
Would my 40-watt iron work better and/or cause damage?
How does one get leverage on the negative terminal tang? – It’s thin metal fused to a flat surface. I can’t seem to get the negative terminal sides to disconnect..

[bddog]

I used to post about this problem. Soldered two. Bought the solid state unit. It is how the stealership deals with it for a reason.

[Spaz]

Along with the solder sucker you can use a heat sink clip or an alligator clip and place it below the solder joint and it'll suck up the heat from the iron so it doesn't travel down to the board.

-Cam

[Simon S]

HELLS BELLS !!! I want to take a ball peen hammer to the SI board and smash it to pieces!
I’ve been reading articles about replacing SI batteries for years – usually, sourcing the right batteries is the hard part.. then just solder new ones in?? Sheeit.. I’m rackin up stupid hours of time on this project so far. I’ve never seen or heard or read about anyone having this much difficulty when replacing these batteries.

I used to post about this problem. Soldered two. Bought the solid state unit. It is how the stealership deals with it for a reason.

Are dealer-available SI boards updated/more-reliable? Do they come with charged batteries?
bma part $131.24 w/ core
part #7 in realOEM diagram (62111377669) $123.73
WTF? What's the difference there? Never seen a realOEM price lower on any part before.

Any information on new SI boards would be appreciated. I'm thinking there's a 1 in 100 chance that my board will work after all the hours of hack-ass, novice, butcher-work I've been up to. Probably turned the board to french toast with heat soak alone. Didn’t see where there’s room for heat-sinking alligator clips.

yes to your removal method, but get something thats going to get really hot. that way, as soon as you touch the joint, it come off and minimizes heat soak of the surrounding components.

Switched to using 40w iron for greater heat.

go to radio shack and buy a $10 solder sucker tool. it's a plastic tube/pencil shaped thing.

also, you'll want to tin the tip of your soldering iron first. google it. :)

I definitely needed to take a crash course in soldering/desoldering. Spent about an hour reading different tutorials and watching various instructional videos. Not much to it really. Keep it clean. Tin tip for heat transfer. Should only take 1-4 seconds. Let the solder flow to/toward the heat. Heat the area you want solder to flow to. Solder should only (really) touch the iron when tinning tip. etc.. I read, watched, learned, and reviewed until the lessons became redundant.

At first I bought a wick – but it didn’t seem to pull anything away. Then I realized/thought/learned that I should be soldering it – THEN desoldering. So I did pick up a plunger/sucker – but it wasn’t like I could solder what was there (oxidized, poor heat, or combination of the two. The terminal tang was flat on the battery and the battery had a rubberized coating that goes right up to the tang’s contact area. Solder would just glob up or jump to the iron tip.

I ended up taking a dremel tool with a fine tip on it and carefully grinding on what appeared to be tack welds on the negative/flat tangs. This – in addition to 2-3 solder/desolder attempts per tang – allowed for the connection to weaken enough for me to pry the thin metal away from the battery. Great! Should be easy sailing from here.. .. except it wasn't.

Used pliers and gently straightened the tangs out (they were mangled from prying on them). Used a dremel tool with stone bit and very carefully cleaned discoloration from the tangs. Took some 220 grit sandpaper and scuffed up ends of new batteries to ensure clean surface and attempt giving the solder something easier to adhere to.

After that – I just couldn’t get enough heat on the tang. Solder would NOT melt/flow to joint. Came back in the house and spent another 45 minutes reading about soldering and watching how-to videos. Noted some instructors were using iron tips that looked like a flat head screwdriver. I had been using a pointy-tip on the iron. It occurred to me that the round/pointy tip wasn’t transferring much heat due to lack of contact area. So then I took an older iron tip and filed it into the flat screwdriver shape, tinned it, and tried it out. It seemed to be better, but still no dice. Sometimes I could get a weak connection – but the tang would practically fall off the battery end if I gently tested the connection with my fingernail.

Before today’s efforts, I examined the other side of the board. The more I look at it, the more I think I should just get a new board.


It looks like connections * might * be good yet – but the caramelized discoloration of the protective coating is concerning.. The worst of the discoloration isn't even opposite of the battery terminals on the other side. I wish I would have inspected this side earlier - it may have been like this before my hack work.


Working off the old tabs with desoldering attempts, dremel tool, and baby flat head screwdriver.


Batteries out. Dremel tool w/ stone.


Cleaned terminal tangs:




Batteries in place. Not soldered.


RTV black silicone seemed to work ok for adhesion and anti-vibration use - although I had to carve it back out after first round of soldering attempts.


Iron tips. Switched out the (brand new) round/pointy tip and reshaped an old one for more contact/heat transfer area.


In an effort to get the solder wire "more into" the desired connection area, I'd take a pair of pliers and flatten the end. I don't know if this interferes with the rosin core's purpose.


This is a sketch I made. Side view of connection and how I've been holding/placing things.


Tomorrow, I'm going to see if I can improve the shape of the iron tip to provide more contact area and therefore better heat transfer. A) people are telling me to make sure it's hot. B) i'm not getting it hot enough.

I'm definitely going to want a new board in the near future - but if this one works, I at least want to give it a shot. Part of me wishes I could skip the solder altogether and just goop the fuckers in place with RTV.

Wish me luck. Feel free to give pointers or let me know if I'm doing something incorrect.

[FredK]

Is the 15-watt iron weak for this job?
Would my 40-watt iron work better and/or cause damage?

Thanks for taking so many pictures! If my SI board fails, now I know what it looks like!

Anyway, those battery tangs need a good deal of heat to get a good solder joint. A 15W Radio Shack iron will not cut the mustard, no matter what kind of tip is on it. I used a 15W RS iron for a small electronics project, and when it came time to solder to a small, small heatsink, the iron didn't have enough heat.

The 40W will work better, and it shouldn't damage the batteries. You'll probably cause more damage holding a 15W iron there for a while.

With regards to proper temperature, make certain the tip of the iron is silvery and shiny. If it is charred, the iron has gotten too hot and has overheated the flux. This char has very poor heat transfer capabilities. It is like trying to cook pancakes on a frying pan that got too hot and charred the sugars of the maple bacon you fried up moments ago.

[Simon S]

Mmmmmmm.. . maple bacon

[Simon S]

Got ‘er done !

Focused on heat transfer.
First, a more aggressive iron tip was shaped. The idea was to increase the amount of surface area contacted.




Then focused on timing. Started by timing how long it took for iron to get hot enough to melt solder (~2-1/2 minutes). After tinning, I timed how long it took for tinning to char as Fred mentions (~1-1/4 min).




I ended up going through cycles of tinning/cleaning iron tip - then waiting ~30-35 seconds prior to use. This provided optimum heat and did the trick. Kept at it until the tangs wouldn't break away from the battery with my fingernail. Soldering into thoses areas where the tang sits flat on the battery-end was new to me. Unlike soldering a component to a board - the solder joint itself isn't something you can see very well - if at all. Dabs of RTV were then applied to the batteries and the board. Didn't want batteries to be held in place by solder joints alone. Using the RTV mimicked the amber-colored glue used to hold original batteries in place.


Felt good getting that board back in.


These are pics of a 'fixture' I made to hold the board stable and vertical while getting the batteries out. (needed more hands!) It's a portion of a box with twist-ties holding the board in place. A clamp was used to secure the box and anchor a puller line of rubber bands on the battery itself. Good times.


Rubber bands were the only thing I could think of to get that last 'hand' on a battery. It was also easy to control amount of pull-force with adjustments to puller line.



Would like to note in this thread that these same batteries (CR14250SE) are also available with tangs soldered on them already. (CR14250SE-FT) Couldn’t find the ones with tabs on Radio Shack’s site though - did find them here but that site had a minimum order quota. I gathered that the tabbed batteries are easier to work with - but (I) don't know how the tangs themselves are removed/fastened to board. If someone could chime in with information on that, it'd be appreciated. De-soldering/soldering on those tabs is something I'd rather not do again..

[bejbis]

Wow, just wow. i didnt read the whole thing, so i might have missed some things. The pictures were enough funny in themselves.

Take the batteries out with the tabs attached, heat the joints on the back of the board and pull them out from the other side. I think thats what you did with your little rubber band setup there on the last post. If not a little too complicated, it was a great way to do what you needed done.

Yeh, you can find the batteries with the tangs attached, it just makes things easier when soldering the original tabs back onto the battery. As the tabs attached to the battery wont work in the board.

The discoloring of the resin on the circuit board is not in itself really a bad thing, usually just age. As long as it isnt flaking off, and the copper traces are not corroding, it usually wont hurt anything.

lLast but not least, get yourself a hotter iron, 15w wont do most jobs, and you usually put more heat into the component using a cooler iron than being half decent with a hotter one. If your worried about applying too much heat to a part, get a damp rag and place it on the part being soldered to absorb some heat. Dont worry too much, the components can take a lot of heat.

[Jean]

rofl..did you get it installed yet, is it working?

[Simon S]

is it working?

hoping to find out late next week. waiting on other parts..

yeah- hell, even i think this shit is funny. glad it's over and hope my embarrassment helps others down the road.

[Jean]

I use a soldering station that way you can control the temp when working with small boards...also soldering wick works for "sucking" the solder away from the board...

also, don't forget to ground yourself and/or desk when working with boards that have IC's in them.

one more - might want to re-flow the solder on that LED attachment board, they tend to have bad joints on them over time.