Author Topic: TSSOP24 Problems  (Read 2614 times)

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Offline necroscope

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TSSOP24 Problems
« on: June 01, 2015, 11:33:41 am »
Having some major troubles with this TSSOP24 package It is a MSH9010LF audio amplifier IC on a LCD TV Mainboard,

 This is the first time I have removed one of these packages and it took some heat with the tweezers seems it was soldered underneath the package for heatsink purposes I presume,
anyway I have never toasted a repair this bad before and removing Surface mount packages is usually a very pleasant experience,Can anyone tell me if they know what has gone wrong in the pic,
i  Think I can faintly see the traces under this weird black stuff that seems to have hardend over the top Or I have ripped the traces off the board and I can faintly see the inner substrates of the pcb,can anyone confirm one of these theories for me?
Thanks in advance.

 

Online wraper

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Re: TSSOP24 Problems
« Reply #1 on: June 01, 2015, 11:42:32 am »
You ripped off the traces.
 

Offline necroscope

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Re: TSSOP24 Problems
« Reply #2 on: June 01, 2015, 11:50:53 am »
Thanks mate...Given the squareness of the way they must have ripped off I wasn't sure if it was some type of infiller I have read about that bakes on black and hardened in the new BGA processes that some rework guys have troubles with,
This Tv is only six months old from manufacture.
Oh well looks like I have at least a days work ahead repairing traces.
 

Offline Psi

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Re: TSSOP24 Problems
« Reply #3 on: June 01, 2015, 12:05:38 pm »
When removing smt IC's with hot air is a good idea to push them side-side until they move and only then try and lift them off.
It stops this from happening.

That said, some pcbs just have terrible glue holding the traces down and they lift up if you look at them funny.
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Offline necroscope

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Re: TSSOP24 Problems
« Reply #4 on: June 01, 2015, 12:46:38 pm »
That said, some pcbs just have terrible glue holding the traces down and they lift up if you look at them funny.

Your not wrong, I cannot believe how easy this all went to Hell....

Found what I was reading a while back...The condition is called "Black Pad" For anyone interested check out the article in the link below, You will also notice the visual appearance looks very similar too what happened to my Pcb.


http://www.atotech.com/products/electronics/final-finishing/recent-publications.html
 

Online wraper

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Re: TSSOP24 Problems
« Reply #5 on: June 01, 2015, 01:17:11 pm »
Found what I was reading a while back...The condition is called "Black Pad" For anyone interested check out the article in the link below, You will also notice the visual appearance looks very similar too what happened to my Pcb.
No, black pad is completely different thing. It is about issues with gold coating (ENIG), not pads lifting off.
 

Offline necroscope

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Re: TSSOP24 Problems
« Reply #6 on: June 02, 2015, 02:43:33 am »
No, black pad is completely different thing. It is about issues with gold coating (ENIG), not pads lifting off.

I think I am in denial about how bad I toasted it...

Thinking about using a TSSOP24-DIP adapter pcb for the repair The VCC is running at 12.54v so I expect to have enough voltage to use it.
 the original circuit was using two ceramic caps in series for smoothing so I am wondering if it will be enough just to replace the original ceramic caps or i should add an extra electrolytic low esr at the vcc pin.....

any sugestions would be greatly appreciated.

Adapter:
 http://www.aliexpress.com/item/FREE-SHIPPING-20PCS-SOIC24-TSSOP24-SSOP24-SO24-SOP24-TURN-DIP24-IC-adapter-Socket-Adapter-plate-PCB/1853581327.html
 

Offline tautech

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Re: TSSOP24 Problems
« Reply #7 on: June 02, 2015, 05:49:44 am »
the original circuit was using two ceramic caps in series for smoothing so I am wondering if it will be enough just to replace the original ceramic caps or i should add an extra electrolytic low esr at the vcc pin.....

any sugestions would be greatly appreciated.
Yes they are for "smoothing" but more correctly de-coupling.
That is, helping prevent any supply spikes from the IC's operation enter the power rails and affect other componentry.

You are confusing de-coupling caps with "bulk" capacitance that is normally cose to the PSU and ocassionally also fitted to remote PCB's. Subtle difference.  ;)

It's very likely any 0.1 uF ceramic cap that you can "shoe horn" into the repair will do the job. SMD or leaded variety.  Best they are as close as possible to the VCC IC pins. Add them last if easiest.  ;)
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Offline necroscope

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Re: TSSOP24 Problems
« Reply #8 on: June 02, 2015, 05:59:18 am »
Yes they are for "smoothing" but more correctly de-coupling.
That is, helping prevent any supply spikes from the IC's operation enter the power rails and affect other componentry.

You are confusing de-coupling caps with "bulk" capacitance that is normally cose to the PSU and ocassionally also fitted to remote PCB's. Subtle difference.  ;)

It's very likely any 0.1 uF ceramic cap that you can "shoe horn" into the repair will do the job. SMD or leaded variety.  Best they are as close as possible to the VCC IC pins. Add them last if easiest.  ;)

Thanks for the advice tautech very much appreciated. :-+
 


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