How to remove a AMC7135 chip for REUSE?

kosPap

kosPap

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hi all! Just to day I received a 4xAMC7135 kit from KD but it was no it, the boards were assembled!

my purpose was to have loose 7135 chips for mods, but now I got to find a way to relaibly removing thme for REUSE....

My plan is to put a thin blade under the chip, unsolder the big pad while putting upwards pressure on the blade...just barely.....when the big pad is off I will have to just lift the board by the chip with tweeezers, heat the 3 "elads" simultanously so that the board will fall off....

Any other methods to? also I have an adjustable soldering iron that can go up to 60W....what is the preffered temp/wattage for this kind of work?

thank you....
 
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paulr

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Normally for SMT rework you would use a hot air desoldering tool.
 
kosPap

kosPap

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let me see... you grab the chip with this, heat on side with the soldering iron, then heat theotehr, presto! chip is off...
 
compasillo

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let me see... you grab the chip with this, heat on side with the soldering iron, then heat theotehr, presto! chip is off...

That's it...
You may give it a try for 1.99$ :)
 
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Th232

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Dunno what kind of gear you have, but my preferred technique for this kind of stuff is to use a hot air tool as paulr said. Two techniques I use:

1) I use a proper hot air desoldering tool for small components, just heat and lift.

2) For larger stuff, I use a regular heat gun, but just tip the board upside down, heat from the now top side of the PCB and let gravity do the actual removal. The beauty is that using this method, heating from the opposite side and letting it fall off via gravity means that overheating is a null issue (at least in my experience, as always YMMV).

Of course, with the second method, lots of other components may fall off as well, so I only use it when I don't care about the remainder.
 
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kosPap

kosPap

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hmmm hot air desoldering tool is out of the equation....

but the other method is a go..I have a gun, and why not, have 4 chips down in oen try with no bent legs too!

THANSK!
 
Al Combs

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As you say a good SMT station is fairly expensive. Two good alternatives are 'solder wick' and a 'desoldering pump' or bulb. The AMC7135's are large enough to not get sucked into a solder sucker.:crackup:
 
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cyclopsed

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I tried the, I call it the "brute force" method.
- cut the board/PCB in it's plane axis into slices (sharp knife)
- once the slice is thin enough, cut it into 4 pieces holding the AMC7135
- sandpaper it until you arrive at the copper, et voilà :shrug:.

Reading the above threads, I tried the following:
- slice the board/PCB, as thin as possible
- cut the slice into 4 pieces (you really don't have to with this method)
- fix a clamp (weight) onto the AMC7135
- turn side with clamped AMC downwards
- heat oposite side a bit with soldering iron until AMC & clamp fall off :twothumbs

That really cleaner than with the "brute force" method, where I had all the time 1 of 6 to 1 of 4 that suffered the mechanical stress and become useless (bottom side of AMC7135 becoming loose and falling off :oops:).
 
Techjunkie

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I do my SMD soldering/desoldering in a copper-core frying pan with the range on low flame :p.

Of course, that's with MCPCB stars, not fiberglass driver boards. Also, even if you did want to try that method with the fiber PCBs, those KD modules are two 1.4A boards fixed back-to-back. You'd have to separate them first somehow.

If you do manage to get them apart without destroying them, please let us know what holds them together (solder or epoxy). Good luck.
 
kosPap

kosPap

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If you do manage to get them apart without destroying them, please let us know what holds them together (solder or epoxy). Good luck.


hm????? I was refering to the 4x chip boards not the 8x...
anyway I tried the hot air gun trick and it worked MARVELOUSLY!

my gun isa cheapo 2000W one and at high
it took some minutes....first the diode gave way, then one chip almost slided off.a tap and it was down....a minute latter and some taps of the liers on the wooden table and all is good....

you will be seeing the board soon cos it will be used for a piggyback board experiment.....

Tips....

1. Put a ceramique plate underneath...you may had close call with teh wife but marring the kitchen table is reason for divorce LOLOL

....the guns blowing air a foot over the plyboard table started burning it....so what for me, it has become my garage bench anyway...

2. no other method woulkd have worked iwth teh AMC chips....the is a soldering pad underneath the chip, so any other method would require an increased force & heat

Th232 thansk again for the tip..it was a life savior....:twothumbs
 
VanIsleDSM

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Wow you guys go to a lot of work to get these things off! Plus they've already been reflowed once, you're doing it again, and then again to resuse them, they're rated for 2 times usually, but not for 3.

So I guess I'll share my super secret technique....

I scrape them off with a razor blade! Goes through the solder without too much trouble.
 
SirJMD

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For removing SMD components, you use a hot air gun - everything else is a sure way to FAIL HORRIBLE.

You could heat up a lump of metal on a stove, place your PCB on it and let it melt the solder - and remove the components twith a tweezer.
 
VanIsleDSM

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Using hot air or a stove a good way to overheat or thermally shock your part when you take it off the pcb and it instantly cools in the air. Assuming they were reflowed with a proper profile the first time, removing them without heat, and then reflowing them again with the proper profile is the only way to stay within manufacturer spec of the chip. Any hand soldering or desoldering is much more likely to cause a failure. Though for simply doing a one of a kind type of project, any method here will most likely work, but there are always always the best ways that make the most sense.
 
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cyclopsed

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hm????? I was refering to the 4x chip boards not the 8x...
so did I understand :))

So I guess I'll share my super secret technique....

I scrape them off with a razor blade! Goes through the solder without too much trouble.

I tried that too, but the bottom side (in fact it was the ground pin with a part of the casing) of the AMC7135 became loose most of the time... so it was :poof:
I guess to much mechanical stress.

But if it works for you, i'm fine with that :))


I do my SMD soldering/desoldering in a copper-core frying pan with the range on low flame :p.

Of course, that's with MCPCB stars, not fiberglass driver boards. Also, even if you did want to try that method with the fiber PCBs, those KD modules are two 1.4A boards fixed back-to-back. You'd have to separate them first somehow.

If you do manage to get them apart without destroying them, please let us know what holds them together (solder or epoxy). Good luck.

I hope you didn't forget to add salt and pepper :p
Hey, we have a star cook in the community :twothumbs

But yep, the double 1.4A's are a bit tricky since they have wires soldered on both sides running trough. Slicing the PCB is a bit tricky.
The wires soldered on both side are sufficient to hold them together, BUT I did not pay much attention if there is more (solder or epoxy).
 
legtu

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I use a soldering iron to remove 7135's. Using a tweezer to put a little bit of upward pull on the component, heat the three small legs at the same time. A few seconds later, you should have the 7135 off the board.

A 40w iron should be fine but I use a 60w. :whistle:
 
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I use a soldering iron to remove 7135's. Using a tweezer to put a little bit of upward pull on the component, heat the three small legs at the same time. A few seconds later, you should have the 7135 off the board.

This is how I do it also. Works every time.
 
kosPap

kosPap

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maybe, but what method theramlly stresses the SMD component LESS? The soldering iron or the hot air gun?

(from past experience and appearence of removed componets I would say the hot air gun)
 

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