In a message dated 07/06/2000 2:24:36 PM Central Daylight Time,
[log in to unmask] writes:

<< Hello

 What are recommendations / experience for optimal standoff height for
 Flipchip designs out there(distance top of substrate to bottom of chip) ?
 Factors I would expect to be effected by this variable are: undefill flow /
 reliability / potential for voids in underfill

 Went through the web but could not get much in terms of hard numbers.

 Thanks in advance

 Wolfgang >>

Hi Wolfgang!

Have you been to Asymtek's web site yet? Go to: http://www.asymtek.com

Then after you get there, click on Tech Tools. There you'll find a whole
bunch of articles and stuff about underfill. There's even some free software
you can download (after you register) called the "Flip Chip Calculator" and
the "Dam and Fill Analyzer".

Flip Chip Calculator

The Flip Chip Calculator offers a quick and easy way to determine the volume
of underfill necessary to optimize flip chip in package and flip chip on
board dispensing processes.

To utilize the application, the user simply inputs parameters including die
proportions, fillet width and solder bump profiles, then selects a specific
underfill material from the list of industry-standard fluids in the program.

The software analyzes these user-defined profiles and calculates the
appropriate underfill volume.

Dam and Fill Analyzer

The Dam and Fill Analyzer provides a quick and easy way to formulate the
optimal dispense parameters for any dam and cavity fill dispensing
application.

The Dam and Fill Analyzer uses volume tolerance formulas to calculate
recommended dam line weight, flow rate and width, along with the recommended
cavity fill material to dispense. Detailed explanations of material data
concerns, process control tips and die package specifications provide a clear
understanding of the process and tolerances involved in IC encapsulation.

To utilize the analyzer, the user simply inputs dispense profile data. Key
profile dimensions include height of wire bonds, dimensions of cavity volume
and solder ball height. With this information, the analyzer quickly computes
the ideal dispense parameters for the user's package and ensures maximum
utilization of cavity fill material. The dispense profile data and analyzer
calculations can be saved to files. The analyzer is available through the
Asymtek web site and on a special CD-ROM by request directly from Asymtek.

-Steve Gregory-

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