(Solved/Done) Desoldering ribbon cable of ipod touch 5th gen - how?

[mjkuwp]

hi All,

Any advice on how I can remove this ribbon cable in preparation of installing the new one?  So far I have not been able to get the solder hot enough to fully melt and flow.  I've tried my hot air station and the metcal iron although my metcal is the smaller unit.  I already have replaced the speaker so nominally I know how to do this.

First I peeled up the adhesive-held material that surrounded the pads.  I also took a layer of tap off from the top of the pads (looked like  Kapton but I don't know what it really is) 

I can turn up the temperature on the hot air (hottest I went was 300C setting) or else maybe I have to get a bigger soldering iron.  What have I missed?  Strangely this is one ipod repair that does not seem to be documented on youtube or elsewhere.

obviously the trick is to remove this without damaging the board and other components.  Otherwise I do understand that with enough heat and energy input these parts will come apart.

The old connector: stuck in place



the new part.




This all started when the home button 'broke'.  It was missing the little black shim on top of the snap switch that interfaces between the button element in the cover and the dome on the switch.  It is about 1.5mm DIA by 1mm tall.  The old switch does not have it - it fell off.  The new switch of course has this little nub but unfortunately for me the switch is part of this really big assembly (pictured above). 


would really love some help - my daughter is going to be super-upset with me if I don't get this fixed : | 

[German_EE]

Are you not trying to unsolder a plug at the end of the cable with the socket on the board? The blue pieces look like pull tabs so it should just come right off.

https://www.ifixit.com/Device/iPod_Touch

[mjkuwp]

Thanks for the quick response!

The ifixit site calls the main board 'logic board'

https://www.ifixit.com/Guide/iPod+Touch+5th+Generation+Logic+Board+Assembly+Replacement/11809

and shows how to remove it but the ribbon cables do not come off.

The blue tabs on the new part would peel back and leave an adhesive but this just secures the ribbon down, it does not make the electrical connection, unfortunately.

This is why I had to peel back the adhesive (at least I thought I had to) on the old part first before attempting to desolder.

What it feels like is that I am trying to desolder on a huge ground plane and I just cannot get enough heat into it.

There is a youtube video that shows this repair but they skip over the desolder/solder portion.  Possibly because they make money on the repair not wanting to give away their techniques?

Either that or what they do to solder/desolder is too ugly for video.

[mjkuwp]

I finally googled upon something.  It must have been a hot bar solder process that installed this ribbon cable.



now...have to conjur a way to do this with regular tools.  Anyone have ideas?  All I can think so far is I need to get a really big chunk of aluminum and heat it above the melt temperature of the solder and apply to the joint.

[KJDS]

http://www.okinternational.com/metcal/english/globalnavigation/products/hand-soldering-systems/tips-and-cartridges/mx-cartridges/smtc-series-blade

[mjkuwp]

Thanks KJDS, good suggestion.

Anyone have a recommendation for what temperature-series to go for in this application?  700 or 800?  It does seem like I will need significant power but I don't know about the temperature resistance of that ribbon cable.

I don't have an MX-500 metcal station at home but we have it at work so all I need to do is buy a tip and try this.

looking like I should have just taken this thing to the Apple store and paid the ransom.  oh well, live and learn 

[Yago]

I have read a thread on here about this subject, alas I can't find it now

Could have a look at chipquik , from what I have seen it will alloy with the solder already on the connector and lower its melting temp for desoldering.

http://www.chipquik.com/store/index.php?cPath=200&osCsid=t05mf6nt25acmv7npnqa6g58f1

[wraper]

I can turn up the temperature on the hot air (hottest I went was 300C setting) or else maybe I have to get a bigger soldering iron.  What have I missed?  Strangely this is one ipod repair that does not seem to be documented on youtube or elsewhere.

I doubt that wit such temperature you will be able to even normally solder usual smt parts on this board. This multilayer board is very good thermal conductor and will sink all heat away and all this combined with lead free solder. You either need preheater or significantly increase temperature an using large tip.

[mjkuwp]

...... This multilayer board is very good thermal conductor and will sink all heat away and all this combined with lead free solder. You either need preheater or significantly increase temperature an using large tip.

Makes sense.  I do have a board preheater so if I disassemble the logic board further I may be able to use that.  I may also buy a junk ipod to test with but frankly I am wondering if I am putting bad money after bad.  at least I may learn something.

Could have a look at chipquik , from what I have seen it will alloy with the solder already on the connector and lower its melting temp for desoldering.

Thanks - Chipquik will work in many applications but I don't know about this one.  The solder is underneath the ribbon cable so anything put on top of the cable will not mix with what is below.

[Yago]

Can the flex be cut around the solder pads(scalpel)?
Gain access to the solder and only have to remove one at a time.

[robrenz]

You need one of these at the proper width.
One minute video here

[mjkuwp]

Got the ribbon cable removed  - thanks all!  I ended up buying a new/used Metcal MX-500P-11 and got a new tip from Thermaltronics.  I also got a wide chisel the same width as the cable but I couldn't make it work - never got good contact across the whole thing and I think the energy just is not enough across that big area.

It was NOT easy.  I ended up cutting the ribbon cable around the soldered area - carefully!  The ribbon cable is surprisingly heavy. Then I put a bunch of leaded solder on the tip to help heat transfer and went at the ribbon part by part.  The area near the center of the device was the hardest (also where I previously tried to start the job). 

NEXT:  I'd love some suggestions on how to finish this job.  Should I somehow try to get each pad tinned with just the perfect amount of solder before gluing that ribbon down?  then apply heat to each pad one at a time?

or...stick it down, then heat the pad and add solder through the top?  There is a small hole in the ribbon on each pad.

Should I clean up the old glue?  I think I should.

I did disconnect the battery before I pulled this ribbon off  - just after powering on the ipod to check it for function one last time.

[mjkuwp]

got it!

I ended up using a relatively small conical tip and the new Metcal station and hit each pad one at a time.  I did tin the pads before I put the ribbon down but I'm not sure I would do it that way again.  It was really  hard to get the right amount of solder on the pads.

I don't know why I didn't think of this... but I should have used paste solder or else tried feeding solder in through the little hole.

I was really lucky to get that connector down and I'd say the connection looked a little lumpy and some of the joints looked cold but the ipod is in use now so I am crossing my fingers.

There were lots of different pieces of tape that had to transfer from the old assembly and move to the new part.  Some copper foil, some Kapton (or similar) tape and also some conductive tape.  It was pretty tricky.  now I can cross "A NEW IPOD!" off my daughter's Christmas list 

[Yago]

got it!

I ended up using a relatively small conical tip and the new Metcal station and hit each pad one at a time.  I did tin the pads before I put the ribbon down but I'm not sure I would do it that way again.  It was really  hard to get the right amount of solder on the pads.

I don't know why I didn't think of this... but I should have used paste solder or else tried feeding solder in through the little hole.

I was really lucky to get that connector down and I'd say the connection looked a little lumpy and some of the joints looked cold but the ipod is in use now so I am crossing my fingers.

There were lots of different pieces of tape that had to transfer from the old assembly and move to the new part.  Some copper foil, some Kapton (or similar) tape and also some conductive tape.  It was pretty tricky.  now I can cross "A NEW IPOD!" off my daughter's Christmas list 

Well done and thanks for posting back how it went.

Sounds like you can cross Metcal from the xmas list too!