Jeff Hempton wrote:

>      Fulton,
>        Just a quick note: if caught before part placement, we instruct
> our
>      operators NOT to wipe the boards before cleaning, and this all
> but
>      eliminated the solder balls. If there are parts on, there is not
> much
>      choice.
>      We use an alcohol based wash/spray system without ultrasonics
> (can
>      damage multilayers?) Good Luck.
>      Jeff Hempton
>      United Technologies Electronic Controls
>
> ______________________________ Forward Header
> __________________________________
> Subject: [TN] Solder-ball
> Author:  Fulton Feng <[log in to unmask]> at Internet
> Date:    7/28/98 11:46 AM
>
> Hi, TechNetter
> I am wondering anybody out there ever experienced solder ball with
> mis-print
> PCB. The scenario is when we have  mis-printed PCB in solder paste
> printing
> process, we used to wipe off the paste with alcohol from the PCB
> surface and
> send them to aqueous cleaner. What happened is when we looked at the
> PCB
> under microscope, we found all the masking edge and vias  sticked with
>
> solder-balls(Solder paste). The solder paste we used was no-clean
> water-soluable paste. The questions are:
> *        Is there any difference in between clean and no-clean paste
> for
> cleaning PCB?
> *        Has anybody used ultra-sonic cleaner for PCB cleaner?
> *       What kind of cleaning agent are your guy using?
> *       Any different approach to take care of this solder-ball issue?
>
> Any input is appreciated!
>
> Thanks in advance!
>
> Fulton Feng
> Nortel
> MPK
>
> ################################################################
> TechNet E-Mail Forum provided as a free service by IPC using LISTSERV
> 1.8c
> ################################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
> following text
> in the body:
> To subscribe:   SUBSCRIBE TechNet <your full name>
> To unsubscribe:   SIGNOFF TechNet
> ################################################################
> Please visit IPC's web site (http://www.ipc.org) "On-Line Services"
> section for
> additional information.
> For technical support contact Hugo Scaramuzza at [log in to unmask] or
> 847-509-9700
> ext.312
> ################################################################
>
> ################################################################
> TechNet E-Mail Forum provided as a free service by IPC using LISTSERV
> 1.8c
> ################################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
> following text in the body:
> To subscribe:   SUBSCRIBE TechNet <your full name>
> To unsubscribe:   SIGNOFF TechNet
> ################################################################
> Please visit IPC's web site (http://www.ipc.org) "On-Line Services"
> section for additional information.
> For technical support contact Hugo Scaramuzza at [log in to unmask] or
> 847-509-9700 ext.312
> ################################################################

   Hi!
I don't understand how ultrasonics can damage multilayers?!
We are using ultrasonic cleaning for misprints and had no problems till
now.
Gaby

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################