Rod/Bill
I concur with those numbers as a worst case.  Actually 20% max (5 - 10%
nom) can be pretty easily achieved with the correct thermal profiles and
the correct paste selection.  Boiling point of the paste volatiles plays
a large part.
Jim Kittel

>-----Original Message-----
>From:  Bill Davis [SMTP:[log in to unmask]]
>Sent:  Wednesday, October 07, 1998 5:03 PM
>To:    [log in to unmask]
>Subject:       Re: [TN] Voiding in BGA
>
>Rod:
>The guidelines we have established here are as follows:
>        Total combined voiding <25%
>        Less than or equal to 3 separate voids
>        No two voids can intersect, irrespective of size/percentage
>
>Another 2cents...
>
>> -----Original Message-----
>> From: Rod Martens [SMTP:[log in to unmask]]
>> Sent: Wednesday, October 07, 1998 2:48 PM
>> To:   [log in to unmask]
>> Subject:      Re: [TN] Voiding in BGA
>>
>> I've never seen an exact number for voiding, but would be interested
>> if anyone
>> does have one.  As for personal experience, we have seen cases where a
>> single
>> large void or many small voids aligned at an interface negatively
>> impacted the
>> reliablility.  Also, we saw a case where some degree of voiding
>> actually
>> increased the life of BGA's, most likely due to some sort of crack
>> arrest
>> mechanism.  I would imagine that a good number for max. voiding would
>> need to
>> include not just % void, but also position in the joint.
>> My $0.02,
>> Rod Martens
>>
>> -----Original Message-----
>> From: Non-HP-FEiranova
>> /hp-ftcollins,[log in to unmask]
>> Sent: Wednesday, October 07, 1998 2:39 PM
>> To: Non-HP-TechNet /hp-ftcollins,[log in to unmask]
>> Cc: Non-HP-FEiranova
>> /hp-ftcollins,[log in to unmask]
>> Subject: [TN] Voiding in BGA
>>
>> To all:
>> Is there a specification to address the maximum voiding allowed
>> for PBGA and CBGA solder joints attached to FR-4 substrate ?
>> Can anybody share some personal experiences in this matter ?
>> Thanks
>>
>> ################################################################
>> 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
>> ################################################################
>>  << File: [TN] Voiding in BGA.TXT >>
>
>################################################################
>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
################################################################