TIM1 sits inside the package, directly against the bare die. It decides whether junction heat leaves the chip, and whether the package survives thermal cycling, aging and warpage. It is the hardest and most overlooked layer in the thermal stack.
Where TIM1 sits
- TIM1 — between die and lid / vapour chamber; direct die contact, thinnest bond line, highest requirements
- TIM1.5 — between lid and heatsink in some package designs
- TIM2 — between heatsink and cold plate; the usual location for gap pads and grease
Chip makers and OSATs screen TIM1 hardest: thermal performance, mechanical behaviour and long-term stability all have to hold at once. Very few material suppliers can ship TIM1 in volume.
Four technical challenges
1. An extremely thin bond line
In-package bond lines run 0.1–0.5 mm. An ordinary 1–5 W/m·K silicone pad contributes too much resistance at that thickness and pushes junction temperature up.
2. Package warpage causes delamination
Large AI dies warp during reflow and power cycling. If the interface cannot follow the gap variation, local voids and delamination follow.
3. No pump-out, no dry-out
Grease migrates to the edges under repeated power cycling and leaves a dry zone. Inside a package, there is no way to service it.
4. Long-term high-temperature stability
The material has to hold its resistance and compression behaviour through sustained heat and thermal cycling.
Our TIM1 approach: vertically oriented graphene pad
| Property | Value | Note |
|---|---|---|
| Conductivity | 180 W/m·K (through-thickness) | Vertically oriented graphene — the high-conductivity axis is the die-to-lid direction |
| Thermal resistance | <0.05 °C·cm²/W @ 50 psi | Low resistance at low mounting pressure |
| Thickness | 0.3 / 0.5 / 0.7 mm (custom 0.2–2.0 mm) | Matched to your BLT |
| Operating temperature | −40 to +200 °C | Covers power devices and high-temperature packaging |
| Aging stability | 150 °C × 1500 h — resistance and compression drift ≤10% | Production-validated |
| Compression | High compression and rebound | Follows warpage and gap variation |
| Form | Solid, no liquid vehicle | No pump-out, no dry-out, no migration |
| Dielectric strength | >5 kV/mm | Insulating layer optional |
Compared with common TIM1 options
| Option | Through-thickness k | Pump-out risk | Pressure needed | Long-term stability |
|---|---|---|---|---|
| Thermal grease | Medium | High | High | Dries out, migrates |
| Phase change material | Medium | Medium | Medium | Limited by cycling |
| Ordinary silicone pad | Low (1–5 W/m·K) | Low | Medium | Permanent compression set |
| Lenecold graphene pad | 180 W/m·K | None (solid) | 10–50 psi | ≤10% drift after 1500 h |
Selection by package type
| Package scenario | Recommended | Note |
|---|---|---|
| FCBGA / large die | EN-PAD-050 | Thin BLT, low resistance, warp tolerant |
| SiP / multi-die heterogeneous | EN-PAD-050 / 070 | Absorbs coplanarity variation |
| 2.5D / 3D stack (incl. HBM) | EN-PAD-030 / 050 + EN-PLT | Low stress, warp resistant |
| Chiplet / advanced packaging | EN-PAD-030 / 050 | Thin, high compression rebound |
| IGBT / SiC power module | EN-PAD-100 + EN-PLT-100 / 200 | 200 °C capable, power-cycling proven |
Samples and validation
- Standard sample 30 × 30 mm (0.5 mm thick), from one piece, die-cut to your drawing
- Samples in about 2 weeks; production 2–3 weeks (standard thickness)
- Test method: ASTM D5470 steady-state resistance; resistance-vs-pressure curves available
- Reliability: 150 °C × 1500 h aging, power cycling, TML/CVCM outgassing
- Documents: batch CoA and dimensional report; full test reports on request
- Engineering support: send die size, warpage, BLT, mounting pressure, power and lifetime — we return a resistance budget and recommended thickness
Want to qualify a TIM1 sample? Send us the package structure — die size, warpage, BLT, mounting pressure, power and lifetime — and we will propose a stack and ship verifiable samples in about two weeks. Talk to engineering →
Frequently asked questions
What is the difference between TIM1 and TIM2?
TIM1 is the interface inside the package, directly against the bare die (between die and lid or vapour chamber) — thinnest bond line, highest reliability demands. TIM2 is the interface between the package and the heatsink or cold plate, usually thicker and under lower pressure. The material requirements are quite different.
Can a graphene pad be used as TIM1?
Yes. Our pad is a solid, compressible through-thickness conductor: 180 W/m·K, below 0.05 °C·cm²/W, validated for 150 °C × 1500 h with resistance and compression drift ≤10%. That suits thin in-package interfaces.
How do you handle package warpage?
High compression and rebound follows the gap. Match the thickness to the measured warpage (0.3 / 0.5 / 0.7 mm) and keep 10–50 psi of mounting pressure to reduce voids and delamination.
Will it pump out or dry out?
No. The pad is a solid material with no liquid vehicle, so the pump-out, dry-out and migration problems of grease do not apply — which matters for an interface that cannot be serviced.
What validation data can you provide?
ASTM D5470 resistance-vs-pressure curves, 150 °C × 1500 h aging (resistance and compression drift ≤10%), power cycling, dielectric breakdown, TML/CVCM outgassing, plus batch CoA and dimensional reports.