SMPS focus
Materials chosen for enclosed adapters, DIN-rail supplies and potted bricks, where conduction is the only way out.
Silicone thermal pads and electrical insulation materials for switch-mode power supplies — MOSFET and rectifier mounting, transformer and bobbin insulation, and die-cut parts for enclosed adapters, DIN-rail supplies and potted bricks. We support 1–2 W/mK conductivity, 0.5–3 mm thickness, adhesive options, and custom die-cut shapes for OEM assemblies.
An SMPS concentrates its losses in three places — the switching MOSFET, the transformer core and windings, and the output rectifier. Because switching is continuous, the thermal load is steady-state rather than peak, so the design case is what the supply does after an hour at full load, not what it does in the first minute at turn-on.
Enclosed adapters, DIN-rail supplies and potted bricks have no airflow at all, so every watt leaves by conduction into the chassis. That makes the interface layer between the device and the chassis a working part of the cooling system, not an assembly afterthought — an air gap of even a fraction of a millimetre in that joint conducts almost nothing.
An SMPS also has a second requirement a purely thermal part cannot satisfy: the primary and secondary sides must stay electrically separated, and the interface material sitting between a live device tab and a grounded chassis is part of that isolation barrier. One correctly specified pad does both jobs. Getting it wrong shows up as reduced electrolytic capacitor life, since capacitor life falls sharply with sustained temperature rise — and the capacitors are usually what ends a supply's service life.
Every watt the switching stage loses has to travel the same road. The junction temperature is whatever the ambient air is, plus the sum of every thermal resistance along that road.
Heat leaves the silicon junction through the device tab, crosses the interface into the chassis or a small heatsink, and only then reaches ambient air. Most of those layers are fixed before the pad is ever chosen — the die, the package and the enclosure geometry are set by the board and the supply's mechanical design.
The interface is the one layer left open, and in an SMPS it is asked to do two jobs at once: carry heat across the joint and hold off the voltage between a tab at switching potential and grounded metal. A silicone thermal pad in that gap cuts interface resistance sharply compared with still air while keeping the isolation barrier intact.
The choice starts from where the pad sits in the supply and what the gap actually measures. A standard adapter running warm in a sealed housing usually needs its air gap closed properly more than it needs a higher-conductivity compound. The table below maps common SMPS types to the grades we supply for them.
| Supply type | Grade | Conductivity | Common thickness |
|---|---|---|---|
| General-purpose adapter, low power | CP100 | 1.0 W/m·K | 0.5–1 mm |
| Standard SMPS, transformer-adjacent | CP150 | 1.5 W/m·K | 0.5–2 mm |
| Higher power density, enclosed brick | CP200 | 2.0 W/m·K | 0.5–3 mm |
| Sealing, gasket seating, vibration | MCF-PU | Not a TIM | 0.5–5 mm, custom |
Conductivity is only half of the choice — where the pad sits on the isolation barrier, its dielectric rating matters as much as its watts per metre-kelvin. Match thickness to the measured gap, not to the largest number on the datasheet.
All three silicone grades are supplied as sheet with or without adhesive backing, and every grade can be die-cut to your drawing. Technical datasheets are linked per grade.
| Grade | Conductivity | Dielectric strength | Thickness options | Adhesive | Datasheet |
|---|---|---|---|---|---|
| CP100 | 1.0 W/m·K | 4.0 kV/mm | 0.5 / 1 / 2 / 3 mm | Adhesive or plain | TDS |
| CP150 | 1.5 W/m·K | 4.5 kV/mm | 0.5 / 1 / 2 mm | Adhesive or plain | TDS |
| CP200 | 2.0 W/m·K | 5.0 kV/mm | 0.5 / 1 / 2 / 3 mm | Adhesive or plain | TDS |
MOQ 10 sheets · typically dispatched in 7 days.
For gasket seating, enclosure sealing and vibration isolation inside the supply, we supply a flame-retardant micro-cellular PU foam. It carries no thermal conductivity rating and is not a thermal interface material.
| Grade | Material | Flame rating | Temperature range | Resilience | Thickness options | Datasheet |
|---|---|---|---|---|---|---|
| MCF-PU | Micro-cellular PU | UL94 HF-1 / HBF | −40 °C to +100 °C | High (≥50 % set recovery) | 0.5 / 1 / 2 / 3 / 5 mm + custom | — |
Grades most often specified for SMPS assemblies, drawn from the live catalogue.
Materials chosen for enclosed adapters, DIN-rail supplies and potted bricks, where conduction is the only way out.
Die-cut pads, combined MOSFET-and-rectifier shapes, and transformer insulation pieces to your drawing.
Reliable bulk supply for power supply manufacturers, contract electronics and industrial OEMs.
Supply terms. Standard sheet grades start at 10 sheets; die-cut TO-package shapes start at 50 pieces. Catalogue grades are typically dispatched within 7 days. Parts to a new drawing are quoted per job — send a DXF or PDF with the grade and thickness, and note that die cost is one-time, so the per-part price falls sharply with volume. Adhesive and non-adhesive options are available across the silicone grades. ISO 9001:2015, supplied to OEMs and contract manufacturers across India from Bengaluru.
For most supplies, 1–2 W/m·K is sufficient — CP100 at 1.0 or CP200 at 2.0. The MOSFET tab is usually clamped to the chassis or a small heatsink, so the pad is doing double duty as the isolation barrier. Choose thickness from the actual gap, not from the conductivity figure.
Because the device tab is often at switching potential while the chassis is grounded. A silicone thermal pad is thermally conductive but electrically insulating, so it carries heat across the joint without carrying current. That is precisely why a pad is used instead of bare metal contact or thermal grease.
Bobbin and layer insulation is a different material family — polyester film, punched-and-folded liners, and aramid paper for higher temperature classes. We die-cut all three to drawing; see our insulation paper catalog.
Adhesive backing helps on automated lines and in vertical assembly, but it adds a little thermal resistance. Where the device is mechanically clamped, non-adhesive usually performs better.
Often yes — a single die-cut part spanning both devices reduces placements and guarantees consistent alignment. Send the board outline and we will quote the combined shape.
Send your specification — grade, thickness, size or die-cut drawing, and quantity — and our team will quote to your requirement.