Guidelines

Intel
®
7500 Chipset Thermal Mechanical Design Guide 43
Design Recommendations for Solder Joint Reliability
Notes:
1. Emin is the minimum principal strain as defined in the Shock Strain Monitoring Customer Reference
Document.
2. These values are for 0.062 inch nominal board thickness.
3. The strain value limits will be different for different board thicknesses. Please contact your Intel Field Sales
representative if your design uses a different board thickness.
The associated risk levels correspond to the likelihood of solder joint failure. A Low level
of risk is unlikely to result in critical to function solder joint failures. When strain
measurements are made from a small sample of boards or systems and fall within the
Medium risk range, there is insufficient information to assess the risk. It is suggested
that additional systems or boards are tested and failure analysis, such as dye and peel,
is conducted to assess the risk. A High risk is likely to result in a significant quantity of
solder joint failures of critical solder balls. A change to the design is strongly
recommended to reduce the bending of the motherboard under shock. Incorporating
the Intel Reference Design Heatsink described in Chapter 6 and Chapter 7 into the
design or adopting the design practices outlined in the System Mechanical Design
Guidance for Dynamic Events - Application Notes/Briefs will improve the strain
response and therefore reduce SJR risk.
§
Table 8-1. Shock Strain Guidance
Shock Strain
(micro strain, µe)
Associated Risk Recommendation / Comments
Emin < 2000 Low Solder joint failure is unlikely
2000 < Emin < 2400 Medium Larger sample size and failure analysis is
suggested for design validation
2400 < Emin High Solder joint failure is likely, consider design
changes to improve reliability