cutting traces, lifting up IC pins, what tool to use?

[CocaCola]

KrisBlueNZ it's all about technique and practice, there is not magic solution that will make it easy... The chipquick stuff works but it's not needed and costly for what it does, it's best to simply practice and get perfection... Also the chipquick stuff is lead based, fine for the US and those countries ignoring ROHS but not so good for those cracking down... You also don't have to spend the premium on the chipquick 'solder' it's just a low melt alloy every company has their own name for this alloy, some examples are 'Alloy 136' 'Indalloy 136' 'Low 136 alloy' 'Cerrolow 136' 'Lens Alloy 136' 'Bolton 136' and so on.... You can purchase a chunk of this and use slice off shavings with a knife to reflow... I have several pounds of it as I use it to make temporary custom jigs for my milling machine and sorts, you can double boil it like chocolate on a hotplate or stove and literally cast it in a cardboard mold, if you want a custom fit to a funny profile you an simply wrap the original part in plastic wrap and pour directly over it Fun stuff to play with if you mind it's toxicity...

As KJ6EAD stated you use a higher heat for less time, but with the higher heat you have to adamantly remember to use less time or you are back to lifting pads... It's like riding a bike, hard at first but once you figure it out painless...

 

[danny davis]

Well I'm using these soldering station that has special attachments in different square shape sizes for SMT and Fine IC chips

You use this soldering iron with the square attachment and desolder the Fine pitch IC chips , what happens is the pads lift off the pcb board

At my older jobs we use hot air guns , which i like because you're not putting HEAT on the pcb like a Soldering iron does with attachments

I like the hot air gun much better for desoldering and doing re-work

 

[CocaCola]

You use this soldering iron with the square attachment and desolder the Fine pitch IC chips , what happens is the pads lift off the pcb board

We went over this in the other thread, the pads are lifting off for likely one of two reasons...

1. You are ripping them off because you are not taking your time and they are still bound by solder... If 39 of 40 pins release and 1 doesn't when you lift the chip it will likely tear the pad... Try sliding the chip off the pads vs lifting... And don't be shy about adding more flux before you attempt the removal...
2. You are cooking the board and thus causing the adhesive that holds the copper to the substraite to fail, you need to not cook the board so long aka reducing heat exposure time... Turn up the heat on the iron and don't cook so long, the higher heat will melt the solder faster before it has a chance to soak into the substrate of the board... And don't be shy about adding more flux before you attempt the removal...

These are operator technique issues and something you as the operator need to fine tune and learn to do correctly... No one likes to admit they are at fault but it's best to swallow that pride if you actually want to get better at something you are not good at...

Is there a reason you can't use a hot air tool?

Go to you local Hobby Lobby (I believe you earlier stated you where in the L.A. area and there are Hobby Lobby's local to you) and pick up this it's $19.99 BUT BEFORE you head out the door go here and print this off this weeks 40% off coupon... For $11.99 you will have a small hot air tool that hardly breaks the bank and will bring joy to your employer as you won't continue to cost them money in destroyed boards......

 

[(*steve*)]

How long do you hold it on the board? It shouldn't take more than a couple of seconds. If it's taking longer you are doing it wrong. (I'm sure I've said this over and over).

Both hot air and soldering iron tips put heat on the PCB.

(Didn't you say you'd never used smd rework tools and were looking for a job?)

 

[danny davis]

No, I have only used Hot air Guns removing SMT and Fine pitch

Is it best to TIN the IC pin first, so when you lift it up off of the pad it doesn't break off?

 

[(*steve*)]

No, I have only used Hot air Guns removing SMT and Fine pitch

Is it best to TIN the IC pin first, so when you lift it up off of the pad it doesn't break off?

How could it be soldered if it wasn't tinned? HOWEVER, it can be useful (especially if you're using a soldering iron) to add more solder to assist the process of transferring heat from the tip to the joints.

You need to heat up the joints (all of them) to a point at which the solder melts so that the device can be removed.

You will have problems (actually very similar problems) if you:

1) Have the temperature too low (and need to heat the device/board for too long before it can be removed).

2) Have the temperature too high (and heat the device/board too much in the time it takes to melt the solder).

and possibly:

3) Fail to allow all the solder joints to melt leading to a damaged device/board.

If you're using a large tip that covers many joints at once, the problems you'll have probably stem from getting it to heat all the joints. Solder on the tip will help this (as will ensuring that the entire tip is hot enough)

 

[KJ6EAD]

As Steve said, you must dress the tip of a package-specific desoldering iron with plenty of solder to create a good thermal bridge. This burns the flux out of the solder so you have to thoroughly flux the leads of the target component. Take a look at this video for more techniques. Most of what you need is in the first 25 minutes.