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Socketed Parts (PLCC)

#19399

Socketed Parts (PLCC) | 5 April, 2002

Good Morning Everyone,

It has recently come to my attention that components (PLCC's)are being placed in the sockets prior to wave soldering. Some of these components are MSD's. They have been overexposed to the atmospere, then are subjected to the wave solder process and are washed with the board. Can anyone shed light on the implications of such a practice. I immidiately see a problem with the MSD issue. Is there any other concerns I should be concious of? Any help would be greatly appreciated.

Thanks

Chris

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JAX

#19400

Socketed Parts (PLCC) | 5 April, 2002

When the remedy is as easy as not inserting the part until after wave........, maybe say at test, you shouldn't need more than one problem. If you think there is a problem, change it. Since we won't know as much about your process as you,( paste/flux types, wave/wash settings, etc...).... I do have one question though! When are they inserting the part?( Slide-line...) Why don't you change the routing for this part, on this assembly, to Test?( or any step after wave if you don't do test.) That way the part is not available to be inserted... That's just my opinion, I could be wrong!

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#19402

Socketed Parts (PLCC) | 5 April, 2002

Hi Jax,

Thanks for the input. I believe that the process at one time was to put the part in just before shipping. There was a problem where some boards shipped without the parts installed. (We do not perform ET on these)As a corrective action, the routing was changed to install the components into the sockets prior to installing the sockets. I do not think this was the best way to address this problem. I'm just looking for all of the potential implications.

Thanks

Chris

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#19404

Socketed Parts (PLCC) | 5 April, 2002

I am surprised to hear that you can wave a socket with or without component in it. What is the orientation of the socket on the board, 0 or 45 degree? Are you sure, you can remove the PLCC out of the socket after soldering? Do you have the designers blessing to expose the PLCC to solder temperature?

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#19409

Socketed Parts (PLCC) | 5 April, 2002

We socket no parts prior to the wave. This practice is an artifact of the days when we�d solder PTH socketed parts from the heat of the wave being conducted through the socket leads to the leads of the component. Sockets??? Thaint sockets no more. So, we quit doing that. And haven�t started since.

Possible issues with socketing PLCC prior to wave soldering are: * Afore mentioned soldering the part into the socket. * Difficulty in properly cleaning flux residues from under the socketed part. * Difficulty in properly drying rinse water from under the socketed part.

Assuming the socket and component are on the primary side and the parts see temperatures <200�F after insertion, there may not be too much reason for concern about MSD precautions.

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#19410

Socketed Parts (PLCC) | 5 April, 2002

I too would be amazed if Chris is wave soldering this socket and component. It's possible that these devices are on the primary side.

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#19489

Socketed Parts (PLCC) | 12 April, 2002

Water trapped under the PLCC (in the socket)during the wash was our reason for installing at final assembly.

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