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Thousands of TSOP or VSOP To be replaced after assembly

Hany A. Salam

#19175

Thousands of TSOP or VSOP To be replaced after assembly | 19 March, 2002

Dear all:

For a dramatic design mistake, we have to exchange a VSOP chip on a few thousands of already assembled PCB's. This is in addition of removing 2 & adding another 2 chip components.

What do you think is the best method, technique or tool could be used to do this?

Hany

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amir

#19177

Thousands of TSOP or VSOP To be replaced after assembly | 19 March, 2002

in regards to repairing all these boards, do they consider the end cost of the product whether it's worth it to do so or not? if it does, would you be able to do it in house? and how labor intense is the job? there are machines out there for mass repair by utilizing laser soldering. its programmbale and it would be done fast. these mahcine are as big as a screen printer. so for a out house repair shop who got such equipment would be lot more cheaper for you to give it to them. the name of the company is BeamWorks.

other then that i don see any other option rather then manual rework.

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#19180

Thousands of TSOP or VSOP To be replaced after assembly | 19 March, 2002

Hany: How could you let this happen? ;-)

The real issue is how best to remove the VSOP. You can argue if there is one clearly superior method. Consider trying several methods and let your operators select the one that makes sense to them.

Replacing the: * VSOP should be done with a hollow soldering tip, like those provided by Pace, that you can load-up with solder and drag across the component leads. Don�t even spend time dressing the pads. All other methods are like Al Czervik [Rodney Dangerfield in Caddyshack] said, �Let's go! While we're young!� * Let your operators choose how to replace the caps. They�ve done it sooo many times. [Well, at least ours have. <= Tweezers and soldering iron??]

Alternatives for removing the VSOP are: * Cut the leads with dikes, remove the part, remove the leads with a soldering iron. Good low tech approach, a trained chimp could do the first two steps. [Our people love cutting leads. There are just so many times they have to be meticulous and SAVE the part.] * Add a U-shaped VSOP tip to your soldering iron, heat, and flick the part off the pads. This is the Al Czervik method of choice. Just line the boards down the bench and go from one board to the next. * Use a hot air hand tool with a specialty tip for your VSOP. Al might like this if the board is thick or has ground planes connected to the component, slowing-down the previous approach. * Use a bench-top hot air rework station.

Removing the capacitors: Cut the component in half with dikes, remove the two halves with a soldering iron. Good low tech approach.

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#19183

Thousands of TSOP or VSOP To be replaced after assembly | 19 March, 2002

For a few thousend boards, I would look into some automation.

In order to get the components off the boards you could run the boards through the reflow oven with the cooling fans turned off. When the boards come out of the oven the solder is still liquid and the two components can be removed with tweezers ( one person on each side of the conveyor )( don't forget the safety glasses and thermo gloves ). You may want to rig up a cooling fan right after component removel and don't let the boards go down the shoot at the end of the conveyor.

You may want to experiment if the remaining solder depot is sufficient for a new component and apply solder cream to the landings or you get a mini stencil and apply solder paste manually. Place the components with a pick and place machine and reflow the boards again.

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Hany A. Salam

#19187

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

Thanks Dave for this contribution. After a lot of discussions with colleagues I found a general tendency to use the air hand tool. Could you please send us detailed steps of using those air guns, considering the distance between the gun & the PCB, temperature, duration & airflow of the gun?

Hany

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Hany A. Salam

#19188

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

Thank you Stefan but unluckyly those board have many PTH components so that they can not re-enter the reflow oven.

But by the way , are you sure that if we switch off the cooling zone we can find the solder still liquid?

Hany

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#19190

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

Your supplier is probably a good place to start.

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#19191

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

there are a few companies using this method to recycle valuable components and make good money with it. The memory boards in computers i.e. could be build with used components.

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CFraser

#19192

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

Guy's I am sorry but your dike removal process for chip components is midievil at best. The fastest way to remove a chip is with 2 solder irons. Place one iron on each end of the component. This process is completely safe and takes about 2 seconds per component. As for your TSOP and VSOP's a hot air tool is the best and safest option. You will need to cover the surrounding components with Kapton or other ESD/Heat repellant tape to reduce additional component reflow.

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Alex K.

#19208

Thousands of TSOP or VSOP To be replaced after assembly | 20 March, 2002

Hello everyone!!

About hot air tool....

Most of the the brands will supply you with specific nozzel for the package to be removed, it will heat up leads only, so you don't have to mask anything (sounds like less work :) ) by the way I had to take about 30 SO-20s it took me 5-8min.

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3D SPI

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