When mounting the DMD important considerations include ensuring a good electrical
connection, and control of the mounting loads (forces) applied to the DMD electrical and thermal areas.
The DMD data sheet specifies the maximum loads for each of these areas.
- Good electrical connection requires:
- Preventing PCB from bending (clamp material and thickness)
- Control of all part tolerances associated with DMD and interposer alignment
- DMD to optical interface, optical interface to Interposer, interposer to PCB
- Preventing interactions from loads applied to the thermal area (heat sink mounting)
- Control mechanical forces on DMD thermal and electrical areas to not exceed data sheet
- Mechanical forces should be uniformly applied (even clamping pressure)
- Partial tightening of fasteners, order of tightening fasteners, possible use of a fixture
- Control of forces by design method (Best method)
- Forces controlled by design details rather than use of fastener torques or special procedures
- Minimize force variations from part tolerances by use of coil springs, flat springs, compressive washers, shoulder screws
- Minimum and maximum force range easily determined and controlled
- Control of forces by assembly process method
- Forces controlled by use of fastener torque and special procedures
- Greater variation and uncertainty of force applied than design controlled method
- Applied forces highly dependent on assembly person and process
- Torque value determined for a specific design (set of materials and fasteners used)
- Difficult to determine clamping forces from fasteners
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