Technical Insight
Thermal-Path and CTE Boundaries in Chiplet, 2.5D/3D, Fan-Out, Interposer, Underfill, Die-Attach, and Molding-Compound Stacks
Panduan rekayasa ini membahas Thermal-Path and CTE Boundaries in Chiplet, 2.5D/3D, Fan-Out, Interposer, Underfill, Die-Attach, and Molding-Compound Stacks, termasuk batas proses, bukti validasi, dan kebutuhan kualifikasinya.
Author: Aurexene Materials Engineering Team · Last updated: 2026-08-28
Jawaban singkat
Petakan masalah termal dan CTE menurut lapisan sebelum memilih material. Identifikasi setiap jalur aliran panas, antarmuka, batas isolasi listrik, ketebalan, densitas daya, tahap perakitan, dan lokasi kegagalan; kemudian korelasikan pengukuran spesimen dan subrakitan dengan paket akhir yang diberi daya. Label kandidat di bawah menggunakan Nitrida Boron Heksagonal (hBN), hBN × AlN (hBNxAlN), and Graphene Copper (Graphene-Cu).
Problem
A package-average conductivity hides local junctions, interfaces, lateral spreading, through-plane layers, heat-sink boundaries, and nonuniform power. The material that lowers one layer's resistance may not control junction temperature, and it may shift warpage or delamination risk elsewhere.
Mekanisme
Thermal behavior combines layer resistance, spreading, contact resistance, interfaces, anisotropy, and external boundary conditions. Thermomechanical behavior combines temperature fields with CTE, modulus, cure shrinkage, thickness, geometry, and adhesion. Because the two networks share the same layers and temperatures, they must be validated together.
Tradeoff
| Stack function | Candidate route | First thermal evidence | Boundary that must remain closed |
|---|---|---|---|
| Molding compound or underfill | hBN or hBNxAlN formulation | Directional compound response and layer/interface resistance | Flow, cure, insulation, adhesion, CTE, modulus, voids, warpage |
| Compliant thermal interface | Insulating ceramic-filled polymer | Bondline thermal resistance at pressure and aging state | Pump-out, dry-out, thickness, leakage, contact and cycling |
| Conductive joint or spreader | Graphene-Cu, Nano Ag, or Nano Cu formulation route | Bulk plus interface/contact response in final geometry | Metallization, oxidation, migration, process temperature, stress and cycling |
The table separates layer functions. A conductive joint material is not a substitute for an insulating molding or underfill layer, and a high bulk value is not a measured package thermal path.
Material Strategy
AX-DND is an evaluation-stage filler route for a defined TIM, underfill, encapsulant, or molding-compound formulation—not a qualified package material. Measure the finished layer’s directional transport, interface resistance, flow and cure, ionic purity, dielectric behavior, CTE, modulus, adhesion, moisture response, and cycling within the complete package-to-cold-plate path.
Use hBN and hBNxAlN only within insulating formulations. Use Graphene-Cu, Nano Ag Powder, and Nano Cu Powder hanya pada jalur konduktif yang memiliki batas metalisasi, oksidasi, migrasi, dan perakitan yang jelas.
Recommended Architectures
- Layer-resolved thermal model: include direction, thickness, area, contacts, power map, and external boundaries; calibrate it with measured temperatures or thermal resistance.
- Coupled thermomechanical model: use the same temperature field and temperature-dependent material data, then correlate warpage, strain, and failure locations.
- Evidence ladder: move from material coupon to layer stack to subassembly to powered package without changing unrecorded geometry or process variables.
Measurement & Validation
Record full stack dimensions, material direction, interface state, pressure, power map, ambient and heat-sink boundaries, assembly and cure or sintering history, moisture, and thermal cycling. Correlate thermal data with warpage, strain, acoustic/cross-section evidence, electrical continuity or insulation, and interface condition.
Qualification Boundary
A model or coupon narrows the design space; it does not qualify the package. Final release requires powered-package correlation, architecture-specific reliability tests, repeat builds and lots, documented limits, and change control.
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Related Comparisons
- hBN vs AlN for an insulating-filler baseline.
Downloads & Engineering Support
Source Basis
Perlu menerapkan batas ini pada mutu, formulasi, metode uji, atau jalur produksi? Bahas bersama Tim Rekayasa Aurexene Materials.