Q:
Do you have any recommendations for using under-fill to strengthen the attachment of the ADIS16475 to a printed circuit board?
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A:
Yes, we can offer some suggestions, for a process that we have used in the past. The intent of this document to offer our customers with a starting point, for developing a process that is able to support all qualification and application level environments.
- After installing the ADIS16475, dry-bake the printed circuit board (PCB), which includes the ADIS16475, for 2 hours, at +125C.
- Place the PCB on to the surface of a 90C hot plate
- Use Henkel FP4470, in 10cc syringes
- Thaw syringes per the instructions in the Henkel TDS
- Attach a pink, 20 gauge EFD/Nordson needle (0.023" ID) to the syringe
- Set the EFD dispenser pressure to 30 psi
- Start in one corner of the ADIS16475 and apply a continuous bead of the material between the PCB and the substrate of the ADIS16475
- Use an "L shape" pattern, while applying the material to only two adjoining sides of the IMU/PCB gap
(NOTE: Application of the material on all four sides can cause entrapment of air bubbles, which will weaken the attachment strength) - Allow the material to flow out to the other two sides of the IMU/PCB interface (which did not receive application of the material from the syringe)
- Cure the material, using a two-stage process:
- +125C, 30 minutes
- +165C, 90 minutes
Acknowledgement to Ed Bradshaw and Tom Richards, for organizing and documenting this process, so that we could share it with this community.
