TVS Diode Thermal Resistance Package Comparison for Power

Overview of Technical Issues:

## Part 2: Natural Language Summary Different TVS diode package structures exhibit varying thermal resistance values that create insufficient heat transfer capability when thermal resistance is too high, causing excessive junction temperature rise during power surge events and leading to potential device failure or reduced protection performance; the goal is to compare package thermal characteristics to select optimal structures that maintain safe junction temperatures under required power handling conditions.

Solution directions generated for this problem

Problem Direction 1 :

ImprovePackage heat dissipation capability
VS
ConstraintPackage structure complexity

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Vacuum adiabatic body and refrigerator
Innovative Solution Refine solution

Distributed micro-via thermal channel array for TVS diode packages

Divide thermal path into parallel micro-channels
How to solve :
  • Replace monolithic copper base with distributed micro-via array (0.3mm diameter, 0.6mm pitch) directly beneath die footprint — each via independently fabricated using standard PCB drilling, eliminating complex multi-layer assembly
  • Implement segmented thermal zones: 25–36 micro-vias in 5mm×5mm area, each filled with standard SAC305 solder (thermal conductivity ≥50 W/(m·K)), achieving collective thermal resistance 18–22°C/W without sintered silver or advanced materials
  • Quality control via automated optical inspection (AOI) for via fill rate ≥95%, X-ray verification of void content <5%, thermal imaging validation at 100W surge showing junction temperature <160°C
  • standard reflow process (peak 245°C, 60s above liquidus) ensures manufacturing consistency
Expected Effect : Thermal resistance 18–22°C/W; process steps same as standard assembly; cost reduction 40% vs sintered silver
Risk Control :
  • via fill uniformity variation
  • solder void formation in narrow channels
  • thermal performance degradation under repeated surge cycles

Problem Direction 2 :

ImprovePackage heat dissipation capability
VS
ConstraintPackage volume requirement

Inspiration 1 : Cross-domain reference

Application Principle: #7 Nested doll
Cross-domain applicability Assess applicability
Semiconductor module
Innovative Solution Refine solution

Hollow vapor chamber embedded in TVS package for zero-footprint heat dissipation

Embed hollow vapor chamber within existing package
How to solve :
  • Replace solid copper base with hollow copper vapor chamber (wall thickness 0.6mm, internal cavity 3.5mm×3.5mm×1.2mm) — vapor phase heat transfer achieves 12–18°C/W thermal resistance within original 5mm×5mm×2mm footprint
  • Inject deionized water working fluid (fill ratio 15–25%, operating range 80–180°C) with sintered copper wick (porosity 60%, pore size 50μm) on inner walls for capillary return flow
  • Seal chamber under vacuum (≤10 Pa) using laser welding at perimeter joints (weld width 0.3mm, penetration depth ≥0.5mm), then mount TVS die on top surface with standard SAC305 solder reflow (peak 250°C, 60s)
Expected Effect : Thermal resistance reduced from 50°C/W to 15°C/W; package volume unchanged; junction temperature during 100W surge drops to 135°C
Risk Control :
  • vapor chamber leak causing performance loss
  • wick structure uniformity affecting capillary flow
  • vacuum seal integrity under thermal cycling

Problem Direction 3 :

ImproveJunction temperature control performance
VS
ConstraintPackage structure complexity

Inspiration 1 : Cross-domain reference

Application Principle: #11 Beforehand cushioning
Cross-domain applicability Assess applicability
Battery and related device, preparation method and preparation equipment
Innovative Solution Refine solution

Phase-change material pre-embedded thermal buffer package for surge temperature control

Pre-embed phase-change material thermal buffer in package structure
How to solve :
  • Embed paraffin-based PCM layer (melting point 140–145°C, latent heat ≥200 kJ/kg, thickness 0.6mm) directly beneath die in standard single-layer package cavity
  • During surge events, PCM absorbs 80–120 J heat via solid-liquid phase transition, limiting junction temperature spike to <150°C without requiring multi-layer heat spreaders or thermal via arrays
  • Use aluminum nitride encapsulation (thermal conductivity ≥200 W/(m·K)) around PCM to ensure uniform heat distribution and prevent leakage, compatible with standard reflow soldering (260°C peak)
Expected Effect : Junction temp <150°C under 100W surge; thermal resistance 35–40°C/W; structure remains single-layer; manufacturing cost +15–25% vs multi-layer designs
Risk Control :
  • PCM leakage during reflow soldering
  • phase transition repeatability degradation after 500+ cycles
  • thermal interface resistance between PCM and die

Problem Direction 4 :

ImproveJunction temperature control performance
VS
ConstraintPackage volume requirement

Inspiration 1 : Cross-domain reference

Application Principle: #36 Phase transitions
Cross-domain applicability Assess applicability
Vacuum-based thermal management system
Innovative Solution Refine solution

Vacuum-assisted phase-change thermal buffer for surge temperature control

Integrate vacuum-sealed phase-change buffer within existing package cavity
How to solve :
  • Embed 0.8g paraffin wax capsule (melting point 142°C, latent heat 210 kJ/kg) in 2mm×2mm×1mm vacuum chamber directly beneath die, absorbing 168J surge energy through solid-liquid transition without volume expansion
  • Apply partial vacuum at 0.3 bar inside sealed chamber to reduce wax thermal expansion by 60% and enhance vapor-phase heat spreading during phase transition, maintaining package footprint at 5mm×5mm×2.5mm
  • Use copper mesh wick structure (0.1mm wire diameter, 40% porosity) surrounding wax to accelerate liquid redistribution post-surge and enable passive resolidification within 5 seconds for repeated surge protection
Expected Effect : Junction temp ≤155°C at 100W surge; package volume unchanged; thermal resistance 28°C/W transient, 45°C/W steady-state; 50% lighter than copper-only design
Risk Control :
  • vacuum seal integrity over thermal cycles
  • wax leakage risk at solder reflow temperatures
  • phase-change material aging after 1000+ surge cycles
Patsnap Eureka Solution