Only a minor observation but, as the offending solder ball has been
conformally coated, the risk of it moving around under the coating to cause
electrical problems has been minimised.
Regards, Graham Naisbitt
__________________________________________________________________________
[log in to unmask]
Concoat Ltd
Alasan House, Albany Park
Camberley GU15 2PL UK http://www.concoat.co.uk
-----Original Message-----
From: [log in to unmask] <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 25 June 1998 00:47
Subject: Re: [TN] Mil-Std-2000A Question
> First I will assume that since this assembly is Through hole you don't
> have terminations less than .020 in.( 5.3.7.4) If the solder ball
> cannot be seen at 4X inspection it is not rejectable. 2000A requires
> 4X inspection with 10 power to be used for referee and identification
> of the DEFECT identified at 4 power, if what you have seen is not
> CLEARLY rejectable 2000A says it shall be accepted.(4.3.1) Since you
> cannot see the solder balls at 4 power you do not have a defect.
>
>
>______________________________ Reply Separator
_________________________________
>Subject: Re: [TN] Mil-Std-2000A Question
>Author: MIME:[log in to unmask] at INTERNET
>Date: 6/24/98 5:26 PM
>
>
> My first response would be that MIL-STD-2000 no longer exists.
>It has been superceded for quite a while now by industry standards such
>as IPC610 and ANSI-J. Those standards will state that if they do not
>violate conductor spacing and are firmly attached (which conformal would
>do a good job of), they are not a reject....
>
>> -----Original Message-----
>> From: Kenny Bloomquist [SMTP:[log in to unmask]]
>> Sent: Wednesday, June 24, 1998 5:08 PM
>> To: [log in to unmask]
>> Subject: [TN] Mil-Std-2000A Question
>>
>> Here is another one of those sticky DOD questions. We have an
>> assembly, TH,
>> Mil-Std-2000A, that has been through assembly, test and conformal coat
>> (UR). As it was being plugged into an end item the operator noticed a
>> solder ball. How it was seen I'll never know because I can not see it
>> through a four power glass. That aside, under a microscope we were
>> able to
>> find 10 or 12 "tiny" solder balls. None of them reduced the conductor
>> with
>> below an acceptable spacing and all of them are encapsulated in
>> conformal
>> coat.
>>
>> Mil-Std-2000A - Paragraph 4.21.4 "Cleanliness of printed wiring,
>> boards and
>> assemblies. Printed wiring, boards and assemblies shall be free of
>> foreign
>> matter. This includes grease, silicones, flux residue, dirt, chips,
>> SOLDER
>> BALLS, insulation residue and wire clippings."
>>
>> My sensible self tells me that since these solder balls (micro-size)
>> do not
>> reduce the conductor spacing and they are encapsulated in UR that we
>> will
>> do more damage reworking these than leaving them alone. I would think
>> that
>> this is a process indicator and not a real defect.
>>
>> The Question: Does anyone out there in TechNet land have the
>> specmanship to
>> work through this or am I all wet?
>>
>> Thanks in advance for all responses.
>>
>> Ken Bloomquist
>> Sr. Principal Process Eng.
>> PRIMEX Aerospace Company
>> [log in to unmask]
>> (425) 881-8990 ext. 6645
>>
>> ################################################################
>> 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 web site (http://jefry.ipc.org/forum.htm) 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 web site (http://jefry.ipc.org/forum.htm) 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 web site (http://jefry.ipc.org/forum.htm) 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 web site (http://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################
|
