Dear Jim,

    What type "a paste dispensing system " do you use ?
    Now we have CAM/ALOT Gemini  II and ASYMTEK M2000, We found dispensing paste 1.0mm Cbga donnot work very well in CAM/ALOT. Can them apply solder paste well?

  Thanks for your help

Best Regards
Liu Changkang

    -----Original Message-----
    发件人: Jim Kittel <[log in to unmask]>
    收件人: [log in to unmask] <[log in to unmask]>
    日期: 2000年10月26日 21:50
    主题: Re: [TN] BGA REWORK
    
    
    We started out not using paste, only applying flux during BGA rework.  After we got our x-ray system we found some of the connections were not wetting well and running out to the edges of the pads.  Now we use solder paste on all BGA’s, down to 0.8mm pitch.  We found it is best applied with a paste dispensing system rather than a stencil.

     

    Jim Kittel

     

    -----Original Message-----
    From: bbarr [mailto:[log in to unmask]]
    Sent: Thursday, October 26, 2000 5:57 AM
    To: [log in to unmask]
    Subject: Re: [TN] BGA REWORK

     

    We do not use solder paste with eutectic balls. In the beginning we did use solder paste just for its flux content. Then we tried using just paste flux and results have been excellent. Our process is:

     

    Remove BGA using hot gas rework station

    Wick residual solder from lands

    Clean

    Apply thin layer of paste flux to lands

    Attach new BGA with hot gas rework station

    Clean

     

    One thing to keep in mind is the nozzle design of the rework station. Some nozzles have a build in standoff to account for the thickness of the solder paste. If you are not using the paste it is possible for the BGA to be dropped onto the lands when the vacuum is turned off after alignment. That may result in misregistration. Do not over apply the flux because that may cause splattering and solder balls.

    Bob
    
    
    Robert Barr
    Manufacturing Engineering
    Formation, Inc.
    Voice: 856-234-5020 x3035
    Fax: 856-234-6679
    email: [log in to unmask] 

    -----Original Message-----
    From: TechNet [mailto:[log in to unmask]]On Behalf Of Bogdan Gabi
    Sent: Thursday, October 26, 2000 5:03 AM
    To: [log in to unmask]
    Subject: [TN] BGA REWORK

    Dear Technetters

    We are starting to rework BGA's.

    A controversy arised about the necessity of solder paste for BGA's with eutectic solder balls.

    Please send your opinion and your general procedure.

    Thank you,

    Gaby