removing socket from type 2 board - glue pulled out tracks

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Guilt-Toy
 

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removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

I removed a eprom from an ecu, all the soiler was sucked out and the chip came out without too much problmems but i noticed Nissan uses glue under the chip and and there are tracks that run to the holes where the eprom connects to.

Basically what has happened is that the glue lifted the tracks for 4 of the pins,

how do you avoid this? and how do you fix it ? i tried to join new wires to the starting point of the track and run it through the socket holes but have not tested if it works yet.

any ideas Matt?
Matt
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Matt »

Its not glue... its conformal coating!

Basically JECS/Hitachi will get a can of this stuff and spray on both sides of the ECU after manufacture. It helps stop water and condensation from affecting the vital digital circuits

If you use acetone or paint thinner and run this on both sides - cleaing the coating from the bottom side so you can desolder properly ... and brushing around the legs at the top so it stops working like glue, then you can desolder properly

Oh and the other main thing I do is after doing the above with paint thinner, is use a flat blade screw driver and push all the pins inwards from the top side

If it is
(a) Cleaned properly with acetone / thinner
(b) Desoldered so the legs are not grabbing on to anything
(c) Legs pushed in to unstick them from any remaining solder in the throughhole and coating

then the chip will literally fall out after that. Its the way I do it these days and have not had a lifted track in a long time

You will need to wire from the throughole to the pin for the broken tracks to fix this one
Guilt-Toy
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

hey matt.

thanks for the info... i tried to soilder them but the ecu still does not respond.. to consult or will not start the engine....

might have to write this ecu off i think... or maybe try again.

is it a bad idea to clean it and use contact spray?
Matt
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Matt »

wont really help much. contact spray is great for cleaning dirty components but usually most ecus are fairly clean already and just need the coating removed

yeah sometimes repairing tracks can be tricky. you need thin single strand wire to do the job properly
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Re: removing socket from type 2 board - glue pulled out tracks

Post by PL »

Some ECU's are definitely worse than others for this. Some chips will literally fall out after de-soldering. Others will stick tight due to the conformal coating wicking under the chip. It all depends what mood the operator was in when they applied the coating!

Best way I've found is to keep applying acetone around the chip with a brush. Clean off as much as you can around the legs, but also apply it around the ends of the chip. You'll see it suck underneath the chip. Keep adding more acetone. It helps a lot if you can leave it sit for awhile as it takes time for the coating under the chip to dissolve.

Lifting tracks won't be due to the coating - it's because it hasn't de-soldered properly. But the de-soldering process can be hindered by having conformal coating left around the pins on the chip side. So do your best to remove all the coating from around the pins before de-soldering.

Another helper is to apply some liquid flux to the underside of the pads once the coating is removed. This improves heat transfer tremendously.

After de-soldering it pays to give the pins a good wriggle from the underside of the board with a small pliers and also, like Matt said, give them a push with a small screwdriver to make sure they break free from the barrel of the through-hole on the board.

Also, check that each pin has de-soldered properly by inspecting from the top of the board. Sometimes the top side will still be soldered. Particularly on power/GND pins. These pins will need to be de-soldered again by applying extra solder (to form a good heat bridge) and allowing a little longer for the heat to get through before pulling the trigger. If you have a helper (or V good soldering skills) you can apply heat using a soldering iron from the top of the board while using the de-solder gun from the bottom of the board. This works very well for power/GND pins.

PL
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

any ways around doing it without a de-soilder gun? resources are a bit limited here...
PL
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by PL »

No good ones.

But one way is to first snip all the legs off the chip from the top side - you'll need a fine side cutters with a nice pointy end. Once they're all snipped you can remove the body of the chip.

Now you can remove the legs one by one. Just grab the leg from the top side with a side cutters (using a pliers will create a heatsink and make it hard to melt the solder) and melt the solder with a soldering iron. They should come out very easily - no brutal tugging!

Now simply go along with solder wick and remove the solder from each hole. Then get some acetone on a cloth and clean up all the mess and you should be sweet.

PL
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Matt »

I ordered my Hakko desoldering gun from Ebay in the US and converted the power adaptor to local voltage. This was to reduce costs (cost several hundred) and also availability of equipment locally

The gun has done very well and I ordered with 1.0mm and 1.2mm tips to use on 8 bit and 16 bit respectively
Guilt-Toy
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

i think the whole problem is that the body of the chip is stuck to the board.

i need to get some paint thinners from somewhere.....
PL wrote:No good ones.

But one way is to first snip all the legs off the chip from the top side - you'll need a fine side cutters with a nice pointy end. Once they're all snipped you can remove the body of the chip.

Now you can remove the legs one by one. Just grab the leg from the top side with a side cutters (using a pliers will create a heatsink and make it hard to melt the solder) and melt the solder with a soldering iron. They should come out very easily - no brutal tugging!

Now simply go along with solder wick and remove the solder from each hole. Then get some acetone on a cloth and clean up all the mess and you should be sweet.

PL
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

thanks for the advice. had just to tool to cut the legs....

managed to get it off without peeling off the tracks this time...

here is a pic, not bad for a second timer with no tools except for a soilder gun, a clicker sucker and some solder wick (damn that shit works great!)

had a look on ebay, been wanting to buy the hakko solder station stuff for the last year or so.... would be nice to have the right tools for the job!
DSC01336.JPG
(1.42 MiB) Downloaded 8025 times
thanks for the help, i am pretty effecient with removing chips now..

now to repair the other ecu :) shit happens...
PL
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by PL »

Good work!

Yes, Hakko de-solder (and solder) gear is definitely the goods. Matt and I have both now imported used Hakko 470 de-solder guns from USA (eBay) and retrofitted 240V transformers for Aussie use. Once you've used a Hakko solder sucker there's no going back. They're great.

Their soldering irons are excellent too. THe 936 series are a bulletproof workhorse of a unit. And their tips (although V expensive) and the best in the business. I've used the same tip daily for years and the tinning is still perfect. Amazing.

PL
Guilt-Toy
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

what was the total cost of the units imported and modified?
Zuikkis
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by Zuikkis »

Z32 ECU's seem to be the worst, they almost always have the coating under the chip so the chip is "glued" to the board..

After too many lifted tracks I started cutting pins on these ECU's. It enough to cut only one side (14 pins), then twiggle the chip back and forth until the other 14 pins are cut. :) Quite fast. The I have an SMD hot air station which will blow the pins right out from the holes and leave nice clean holes..
Guilt-Toy
 

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Re: removing socket from type 2 board - glue pulled out tracks

Post by Guilt-Toy »

Yeah you can see where the glue attatchs the chip to the board when you take the chip out. Glad i am not the only one who had this issue... sad to say this ECU is pretty much a write off. not usable at all and not repairable.

cutting the chip made things much easier, but the one i did the chip was still glued to the board so even after cutting the pins the chip was still stuck a little.

Zuikkis wrote:Z32 ECU's seem to be the worst, they almost always have the coating under the chip so the chip is "glued" to the board..

After too many lifted tracks I started cutting pins on these ECU's. It enough to cut only one side (14 pins), then twiggle the chip back and forth until the other 14 pins are cut. :) Quite fast. The I have an SMD hot air station which will blow the pins right out from the holes and leave nice clean holes..
Matt
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Re: removing socket from type 2 board - glue pulled out tracks

Post by Matt »

Search 'Hakko 470' on ebay.com

There are a number of units on there from $50USD- $300USD on there. Power supply to replace was about $40AUD from memory

Make sure it has a working gun. You can get replacement parts (sticks to clean the gun, tool to remove the tips whilst hot, filters, spare tips etc) also so see what comes with the unit when you look through them
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