Thermal Conductive Adhesive Degassing Solution

From material properties to process parameters, one-stop solution for bubble issues of thermal conductive adhesives


Thermal Conductive Adhesive is a functional adhesive material using polymer matrix (silicone, epoxy resin, polyurethane, acrylic, etc.) filled with high proportion of thermal conductive powders (alumina, aluminum nitride, boron nitride, etc.). Its core function is to build efficient heat conduction path between electronic components and heat sinks, while providing mechanical bonding, electrical insulation and environmental protection. Due to high filler loading and high viscosity, thermal conductive adhesives easily entrap air bubbles during mixing, filling and coating. Residual bubbles will seriously weaken thermal conductivity and bonding reliability. Sinos provides complete degassing solutions covering materials and processes for various thermal conductive adhesives via self-developed planetary mixing & degassing technology.


◆ Material Properties

Common Matrix Types

Silicone, Epoxy Resin, Polyurethane, Acrylic

Thermal Fillers

Alumina (Al₂O₃), Aluminum Nitride (AlN), Boron Nitride (BN)

Filler Content

60%~85% (by weight)

Thermal Conductivity Range

0.8~5.0 W/(m·K)

Typical Viscosity Range

500~50,000 cps

Typical Application Scenarios

LED, Power Modules, Power Batteries, 5G Base Stations, Automotive Electronics


◆ Mature Application Fields

Thermal conductive adhesives are widely adopted in core heat dissipation scenarios of electronics, electrical and new energy industries. Below are main application fields and typical working conditions:


💡 LED Thermal Management

Thermal bonding between LED chips and aluminum substrates/heat sinks. Thermal silicone commonly used, viscosity 1,000~5,000 cps, thermal conductivity 1.0~3.0 W/(m·K)

🔋 Power Battery Thermal Management

Thermal structural bonding between cells and cold plates/modules. Thermal gel or silicone commonly used, viscosity 5,000~30,000 cps, high thermal conductivity & flame retardancy required

📡 5G Base Station & Communication Equipment

Thermal filling for power amplifier modules, RF chips and heat sinks. Thermal silicone/gel, thermal conductivity ≥2.0 W/(m·K), low thermal resistance required

🖥️ Consumer Electronics Heat Dissipation

Thermal interface filling for mobile SOC, tablet chips and laptop CPUs. Low-viscosity thermal silicone, viscosity 500~3,000 cps, ultra-thin coating required

⚡ Power Modules & Power Semiconductors

Thermal potting and bonding for IGBT modules, MOSFETs and power adapters. Thermal epoxy potting adhesive, viscosity 8,000~20,000 cps, high insulation requirement

☀️ PV Inverters

Thermal bonding & potting for power modules and heat sinks of inverters. Thermal silicone/epoxy adhesive, high temperature resistance, UV resistance and long-term reliability required

🚗 Automotive Electronics

Thermal potting for ECU units, on-board sensors and OBC chargers. Thermal gel or silicone, AEC-Q automotive qualification required

🏭 Industrial Control & Frequency Converters

Thermal filling for PLC modules and power devices of frequency converters. Thermal silicone/gel, long-term high-temperature aging resistance & vibration resistance required

🔌 Energy Storage Systems

Thermal structural bonding and potting for battery packs and PCS converters. Thermal gel/epoxy adhesive, flame retardancy, high thermal conductivity and long service life required


◆ Core Issues Caused by Bubbles

📉 Degraded Thermal Performance

Air bubble thermal conductivity is only ~0.025 W/(m·K), far lower than adhesive matrix. Test data shows each 1% rise in void ratio reduces overall thermal performance by 0.8~1.2 W/(m·K).

🔌 Electrical Insulation Failure

Bubbles form partial discharge channels, lowering volume resistivity and dielectric strength, creating breakdown risks under high voltage and affecting product safety certification.

💔 Reduced Bonding Strength

Bubbles create internal stress concentration points and void defects, weakening interfacial bonding strength and triggering delamination & cracking during thermal cycling.

⏱️ Uneven Filler Sedimentation

High-specific-gravity thermal fillers settle naturally during static storage, leading to inconsistent filler distribution between upper and lower layers, fluctuating thermal conductivity and poor batch consistency.


◆ Recommended Process — Planetary Mixing & Degassing

Planetary mixing & degassing is the core process to eliminate bubbles in thermal conductive adhesives. Through rotation + revolution planetary motion, efficient mixing and degassing are realized without damaging filler structure.


Step 1  Pre-mixing

Fully mix component A for 5~10 min to eliminate filler sedimentation. Weigh A/B components by weight with error ≤±1%

Step 2  Cup Loading & Parameter Setting

Select rotating speed based on viscosity (low viscosity:1500~2000rpm, medium viscosity:2000~2500rpm, high viscosity:1500~2000rpm)

Step 3  Mixing & Degassing

Rotation and revolution run synchronously. Vacuum assistance (-95KPa) can be applied for medium & high viscosity materials to boost efficiency

Step 4  Discharging & Potting

Use adhesive immediately after degassing, inject slowly along wall. For complex cavities, segmented potting + secondary degassing is recommended


◆ Recommended Equipment

  1. MIX60 for low-viscosity thermal conductive adhesive; viscosity ≤5,000 cps • Laboratory & small batch scenarios • Rotation+revolution planetary motion • Easy operation & quick cleaning • Vacuum module optional

  2. MIX90 for medium-viscosity thermal conductive adhesive; universal model covering mainstream thermal adhesives • Balanced mixing & degassing efficiency • Optional vacuum (-95KPa) • Suitable for small & medium batch production lines

  3. MIX1000PLUS for high viscosity & high throughput; viscosity 15,000~50,000 cps • Production-grade planetary mixer-deaerator • Large capacity & outstanding efficiency • Industrial continuous operation • Vacuum module as standard

  4. MIX2000 for mass production; high capacity demand • Large-volume industrial degassing machine • Stable operation & simple maintenance • Suitable for long continuous operation • Vacuum module as standard


◆ Test Cases

Below are measured degassing cases for thermal conductive adhesives of different viscosity grades, verifying the applicability of planetary mixing degassing process in various thermal adhesive scenarios.


▶ Case 1: Low-viscosity Thermal Silicone

Item

Parameter

Test Material

One-component thermal silicone (silicone matrix, alumina filler)

Viscosity

Approx. 3,000 cps

Test Model

MIX60

Vacuum Degree

-95 KPa

Rotation Speed

2,000 rpm

Duration

3 min

Temperature

Ambient (25℃)

✅ Degassing Result: Bubbles fully removed, adhesive becomes uniform and dense with consistent filler distribution and restored good fluidity. Ready for potting or coating process.


▶ Case 2: Medium-viscosity Thermal Epoxy Potting Adhesive

Item

Parameter

Test Material

Two-component thermal epoxy potting adhesive (A/B=5:1, composite filler of alumina + aluminum nitride)

Viscosity

Approx. 10,000 cps after mixing

Test Model

MIX90

Vacuum Degree

-95 KPa

Rotation Speed

2,000 rpm

Duration

5 min

Temperature

Ambient (25℃)

✅ Degassing Result: Bubbles completely eliminated with smooth liquid surface. A/B components mixed homogeneously without streaks or color difference. Fillers dispersed evenly without sedimentation or delamination. Cured adhesive is dense and void-free with stable thermal conductivity.


▶ Case 3: High-viscosity Thermal Gel

Item

Parameter

Test Material

High thermal conductivity gel (silicone matrix, highly filled spherical alumina, thermal conductivity ≥3.0 W/(m·K))

Viscosity

Approx. 35,000 cps

Test Model

MIX1000PLUS

Vacuum Degree

-95 KPa

Rotation Speed

1,800 rpm

Duration

8 min

Temperature

Ambient (25℃)

✅ Degassing Result: Bubble removal rate＞98% for high-viscosity paste, adhesive returns to dense & uniform state. Consistent filler distribution, no agglomeration or delamination. Smooth surface after coating without bubble traces, thermal conductivity meets specification.


◆ Comparison Before & After Improvement

Comparison Item

Before Degassing

After Degassing

Thermal Performance

Bubbles lead to significant drop of thermal conductivity

Stable thermal conductivity, reduced thermal resistance

Filler Distribution

Filler sedimentation & agglomeration, uneven distribution

Fillers uniformly dispersed, no agglomeration or delamination

Bonding Reliability

Bubbles cause stress concentration, prone to delamination and cracking

Dense adhesive matrix, greatly improved bonding strength

Electrical Insulation

Bubbles form discharge channels with breakdown risk

Restored dielectric strength and reliable insulation performance

Batch Consistency

Unstable effect with large batch-to-batch difference in conventional methods

Reproducible parameters, excellent batch consistency

Product Service Life

Bubbles and agglomeration trigger local overheating and accelerated aging

Uniform heat dissipation, extended product lifespan


🎯 Free Sampling Test
   Send your thermal conductive adhesive samples. We will test degassing parameters and issue test reports.