7.2 Pressure Specification
To avoid damage to the GPU (die or solder-ball joint cracks) caused by improper
mechanical assembly of the cooling device, follow the following recommendations:
• It is recommended that the maximum pressure that is evenly applied across the
contact area between the thermal management device and the die does not
exceed 75 PSI. A contact pressure of 30-40 PSI is adequate to secure the
thermal management device and to achieve the lowest thermal contact
resistance with a temperature drop across the thermal interface material of no
more than 3℃. Also, the surface flatness of the metal spreader should be 0.001
inch/1 inch.
• Pre-test the assembly fixture with a strain gauge to ensure that the flexing of
the final assembled board and the pressure applying around the GPU package
will not exceed 600-micron strain under any circumstance. For strain gauge
setup and test methodology, refer to industrial standards (IPC/JEDEC-9704 -
Printed Wiring Board Strain Gauge Test Guideline).
• Ensure that any distortion (bow or twist) of the board after SMT and cooling
device assembly is within industry guidelines (IPC/EIA J-STD-001). For the
measurement method, refer to the industry approved technique described in
the manual, IPC-TM-650, section 2.4.22.
7.3 Board Solder Reflow Process Recommendations
7.3.1 Stencil Opening Size for Solderball Pads on PCB
Warpage of the PCB and the BGA package may cause solder-joint quality issues at
the surface mount. Therefore, it is recommended that the stencil opening sizes be
adjusted to compensate for the warpage. The recommendation is for the stencil
aperture of BGA balls to be kept as the same size as the PWB BGA pad design.
Mechanical Data 73
© 2017 Advanced Micro Devices, Inc.
AMD Confidential - Do not duplicate.
"Vega 10" Databook
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