Thermal insulator pads

These pads need to be capable of withstanding high power and high voltage applications. Fiberglass is commonly used for protection and a high breakdown voltage is needed for isolation. These materials must be tear, puncture and cut through resistant and should be applied either by stencil print or pre-applied.

Two insulator pads that are commonly used for Solar applications are:

• Honeywell TIP3500 | 3.5 W/mK insulator pad with, 6000V Breakdown Voltage
• Honeywell TIP5000 | 5 W/mK    insulator pad with 4500V Breakdown Voltage

Phase change materials

Solar applications require phase change that can be used for high power applications. The major requirement is the ability to fill bondlines that are thinner than 0.1mm while retaining low thermal impedance and stability. These materials need to display high reliability and minimal to no pump out.

Some phase change materials that are used for Solar power systems are:

• Honeywell PTM 7000
• Honeywell PTM 7950

Thermal Gap fillers

Gap fillers are either liquid or pad materials that must be able to effectively dissipate heat while also be soft to relieve mechanical stresses. These materials should be able to fill a wide range of gaps (ranging from 0.1mm to 5mm) and typically come in custom sizes that can be applied to automatic processes.

Some thermal gap pads and liquid hybrid fillers that are used for Solar power systems are:

Gap Pads

• Honeywell TGP 3000
• Honeywell TGP 6000

Liquid Hybrids

• Honeywell HT 3500
• Honeywell HLT 7000

Potting Encapsulants

These materials are typically used for power storage and single/three phase inverters. They need to have basic thermal conductivity but more crucially we want to control their stress properties. Low shrinkage and low CTE post curing are needed. Low viscosity is also important so that the material can flow everywhere within the package. Liquid encapsulants need to be electrically insulating to avoid any shorts and flame retardant to ensure safety and reliability. Main three chemistries and recommended products are:

Silicones:

• Loctite SI 5140
• Loctite SI 5145
• Loctite SI 5952
• Loctite SI 5954

Epoxies:

• Loctite STYCAST 2850FT

Urethanes:

• Loctite STYCAST U2500

Conformal coatings

Conformal coating ensures stress relief during and after thermal cycling and thermal shock. They need to have a wide range of viscosities that can be used for various applications. These coatings are usually jettable and need to be soft with low modulus and CTE that will protect the surface of the package without affecting it. Moisture and chemical resistance is also crucial.

Silicones:

• Loctite SI 5293

Urethane Acrylates:

• Loctite STYCAST PC18M