Thermal Interface Materials are installed between a heat-generating device and a heat sink or chassis to facilitate heat transfer.
• Die-Cut Pads
• Tight dimensional control
• Range of materials – Polymer, metal matrix, carbon/carbon composite
• Can include adhesive pads Liquids
• Fills gaps more completely
• Range of materials: – Grease, silicone, epoxy
• No mechanical stress
• Some require curing
Thermal management starts with the circuit board and electronics package
• Various thermal management approaches include:
– Board-level attachment (through-hole vs. surface mounted)
– Heat sinks
– Metal base plates (e.g. copper, aluminum)
– Constant-current power supplies
– Fans
• Heat is generated on the underside of the chip and travels through a metal block, known as a “slug”, to solder points on the circuit board, and eventually to a heat sink where it is dissipated.
• The selection and use of materials for attachment/assembly are vital
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Thermal Interface Materials (TIMs) range from thermally conductive adhesives to die cut pads that are electrically isolating, as well as thermally conductive
Considerations of Thermal Materials
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Operating temperature
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Dielectric strength
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Bond strength
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Surface wet-out
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Shock performance
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Packaging constraints
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Airflow
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Surface flatness (substrate, heat sink)
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Shape/type of metal used for heat sink
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Applied mounting pressure
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Thickness of the interface and contact area
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Production requirements and part size
Flexible Pads, Tapes, Films
• Easily die-cut to complex shapes
• Excellent high temperature, abrasion, and chemical resistance
• High or low conductivity
• Can be coated with an adhesive on one or both sides
• Formulated to achieve specified performance values in terms of dielectric strength, thermal conductivity, and thermal impedance
• No clean-up or cure time
• Dispensing machinery not required
• Smooth surfaces
• Can be pressure-sensitive