1. Do you know of a source for dummy practice parts other than TopLine?
They don't have this particular size.

WE TYPICALLY HAVE TO PURCHASE PARTS (EITHER EMPTY PACKAGES OR ELECTRICAL
FALL-OUT) RIGHT FROM THE COMPONENT SUPPLIER.

2. Comments about OSP pad finishes? Will they tolerate all the process
steps and still protect against oxidation at the latter stages? It could be
that the process may stretch out over several days. e.g., reflow and wash
day one, second reflow and wash on day two or three, and then final through
hole and wash on day four or five. Anything could stretch out the over-all
process time such as weekends and holidays.

3. What about other pad finishes? Palladium, Gold, Plain old hasl?

NO EXPERIENCE WITH OSPs OR OTHER FINISHES

4. What stencil thickness for BGA? Do you find .006" sufficient? Have you
experienced bridging with .008"?

WE USE .008, HAVE USED .010" WITHOUT BRIDGING ON COMPONENTS WITH SN10 SOLDER
BALLS.

5. Did you find that your oven profile changed drastically from that used
for boards with, say, 200+ pin leaded devices?

OVEN PROFILES HAVE CHANGED FOR US BUT WE CHANGED TO RATHER LARGE CERAMIC BGAs.

6. What about solder mask defined pad areas as opposed to SM opening bigger
than the pads?

OUR DESIGN DOES NOT USE SM DEFINED PADS.  TO DATE, I HAVEN'T FOUND A REALLY
GOOD REASON TO USE THIS DESIGN.

7. With this large of a device (40mm x 40mm) I am concerned about CTE
mismatch over the operating temp range specified as well as the process
temp range to which it will be exposed.  What board materials would you
recommend?  Would you spec one of the higher Tg materials?  Why?  I will
need to provide cost justification for wanting this more expensive and for
some shops, more difficult to process, material.

SINCE YOU'RE USING A PLASTIC PART, THE TCE MISMATCH SHOULDN'T BE THAT GREAT
BETWEEN THE COMPONENT BODY AND THE BOARD.  YOU WILL HAVE A LOCAL TCE MISMATCH
BETWEEN THE SOLDER AND THE COMPONENT OR BOARD, THOUGH.  YOU REALLY NEED TO DO
SOME TESTING (THERMAL CYCLING) OR FINITE ELEMENT ANALYSIS TO DETERMINE THE
RELIABILITY OF YOUR DESIGN.

8. What are your responses to the questions above for Micro-BGA?

NO EXPERIENCE

Jim Marsico
AIL Systems, Inc.
(516) 595-5879
[log in to unmask]

--Boundary_[ID_QNcXvAVcIkYf9q4ywL9ZKw]--

##############################################################
TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################