To operate efficiently and ensure reliability, heat must be removed from heat generating power components.
As a result of faster speeds, reduced format, and more devices being populated on PCB’s, more heat is being generated that must be removed for efficient operation.
The move to sustainable-energy increased the demand for energy management electronics which also create much heat because of the high electrical currents as used on these applications (Power inverters for solar and wind-energy, powertrain electronics for HEV)
Thermal management through various applications aids in directing heat away from heat generating system components.
The following are a review of various thermal management approaches, applications and capabilities that can be supported.
Thermal Management Types Offered
PCB Thermal Management –Pressure Sensitive Adhesive for Aluminum and copper
Pressure sensitive adhesive (PSA) is a lower cost option for attaching pallets / coins or plate-heatsinks to a PCB where electrical conductivity is not required.
Pressure Sensitive Adhesive advantages
- Does not require a heat source for bonding, thus simplifying the bond process
- Bond to low surface energy substrates or surfaces
- Resists dielectric breakdown
- Relatively high Thermal resistance of tape
- Can meet aerospace and medical requirements
- Used in high volume in automotive applications (surface attached heatsinks).
Old technology. Probably less demand in future as customers moving to alternatives.
Aluminum-plate Heatsink Process Flow.
Raw material and production
3M Adhesive film
Al heat sink
Main Process equipment used for ‘Aluminum-plate Heat-Sink’
PCBA Adhesive Tape roller pressing
1st laminating For PCB , Adhesive and Al plate
Final Hydraulic pressing
Copper Heat-Sink board
Copper Heatsink (heat-spreader).
On bottom-side the component-housing is soldered to GND-plane which contains thermal-Vias to conduct the heat to heat-sink.
Copper Heat-Sink board
Heat Sink Pick and Place machine is used to assemble copper heat-sink to PCB.
These copper heat-sinks are much thinner and smaller than the aluminum-plate heatsinks so suitable for Pick and Place process.
The automated process includes both ‘pick and place’ and ‘pressing’ of the copper heatsinks.
Main Process equipment used for the automated ‘Copper Heat-Sink’ process.
Pick and Place
Customer test requirements for ‘copper Heatsink process’ includes
- Voltage test (no electrical flash over at room temperature and 100V)
- Solderability test (no delamination in the solder bath 288ºC/20sec.)
- Adhesion test (the adhesive strength must be > 0.5N/mm)
- Temperature cycle test (no delamination in 200 test cycles)
PCB Thermal Management – Heat Sink Paste
- Heat Sink Paste (HSP) Thickness: 0.15mm
- Position tolerance (e.g. HSP to PCB): /-0.2mm
- Application by means of silkscreen printing process
- Can be printed with the suitable geometry needed
- Printing and curing in two steps (75um per step )
- Final layer thickness 160 um
- Excellent heat conductivity (2 W/mk)
- High Isolation [ 30 KV/mm ]
- Resistant against AFT/Isolation layer of Cu Structures against AFT
Heat Sink Paste (HSP) Examples
4L HSP PCB
4L HSP PCB
6L HSP PCB
Cerra Systems Boards Fabrication capabilities support high-frequency PCB, High-temperature Boards, Thick PCB, ultra-thin PCB, heavy copper PCB, Metal Core PCB, HDI boards with Blind Vias, Buried Vias, Micro Vias, Embedded passives, bonded heat sink, Impedance Control, Depth control drilling, Back drilling, Edge Plated PCB, Bump Pads, cavity with ledge, Via on pad and stacked micro-Via technology.
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