What Is SiP Adhesive?
SiP (System in Package) adhesive refers to the family of adhesive materials used to bond, attach, and protect multiple die and passive components within a single semiconductor package. Unlike single-chip packages, SiP integrates heterogeneous components — processors, memory, sensors, passives — into one package, requiring adhesive materials that can handle diverse substrate materials, varying bond line thicknesses, and multi-step assembly processes.
COFA manufactures a range of semiconductor packaging adhesives specifically formulated for SiP assembly: die attach adhesives for chip bonding, underfill materials for flip chip interconnects within SiP, and structural adhesives for component fixing.
Our SiP adhesive portfolio includes heat cure, UV cure, and dual cure (UV + heat) options to accommodate different process flows and throughput requirements.
SiP Packaging Applications
Mobile SiP Modules
Smartphone and wearable SiP modules integrate application processors, power management ICs, and RF components. Adhesive requirements include low warpage (thin substrate), fast cure for high throughput, and drop-test reliability. COFA low-stress die attach adhesives (5001S, 5002S series) are designed for these applications.
MCP (Multi-Chip Package)
MCP stacks multiple memory die or combines memory with logic die. Die attach adhesives must provide uniform bond lines across stacked die while maintaining low voiding. COFA die attach materials offer controlled fillet shape and minimal die shift during cure.
PoP (Package on Package)
PoP stacks a logic package (bottom) with a memory package (top) using solder balls. Underfill between the top and bottom packages prevents solder joint failure during board-level thermal cycling and drop events. COFA capillary underfill provides reliable PoP protection.
IoT and Sensor SiP
IoT sensor modules combine MEMS sensors, analog front-end ICs, and wireless communication die. These applications require adhesives compatible with temperature-sensitive components (low cure temperature) and various substrate materials including LTCC, organic, and flexible substrates.
COFA SiP Adhesive Product Matrix
| Product | Type | Cure | Application | Key Feature |
|---|---|---|---|---|
| COFA 5001S | Die Attach | Heat (150°C) | SiP, MCP die stacking | Low stress, low warpage |
| COFA 5002S | Die Attach | Heat (120°C) | Thin die, flexible SiP | Ultra-low stress |
| COFA 3100H | Board Reinforcement | Heat (80°C/30min) | SiP substrate reinforcement | Fast low-temp cure |
| COFA 3200H | Board Reinforcement | Heat (120°C) | SiP structural bonding | High hardness |
| COFA 4100FU | Underfill | Heat (130°C/30min) | Flip chip within SiP | High flow, low CTE |
| COFA 1001D | Module Bonding | UV + Heat | Camera/sensor SiP | Dual cure, high toughness |
Key Material Properties for SiP Adhesives
- CTE (α1) — Must be controlled to minimize warpage when bonding silicon die (CTE ~3 ppm/°C) to organic substrates (CTE ~15 ppm/°C). COFA die attach materials are formulated with optimized filler content for CTE balancing.
- Viscosity — Die attach applications require controlled viscosity for precise dispensing and controlled fillet formation. Range from 5 Pa·s (thin bond line) to 60 Pa·s (gap filling).
- Tg (Glass Transition Temperature) — Above the maximum operating temperature of the final application. COFA SiP adhesives provide Tg >130°C for consumer applications and >150°C for automotive-grade requirements.
- Modulus — Low modulus variants (5001S, 5002S) absorb thermal stress in thin die stacking. High modulus variants (3200H) provide rigid structural support.
- Cure Temperature — COFA offers cure temperatures from 80°C to 150°C, enabling process compatibility with temperature-sensitive components in SiP.
Reliability Considerations
SiP reliability requirements vary by end application:
- Mobile/Consumer — JEDEC Level 3 MSL, -40°C to +85°C TCT (500 cycles), board-level drop test (JESD22-B111)
- Automotive — AEC-Q100 Grade 2 or 3, -40°C to +125°C TCT (1000 cycles), HAST 96hr
- Industrial/IoT — -40°C to +105°C TCT (1000 cycles), 85°C/85%RH steady-state testing
COFA SiP adhesive materials are designed to meet these reliability standards. We provide application-specific technical support for material selection and process optimization.
Process Compatibility
Dispensing
Compatible with jet dispensing, needle dispensing, and stamping transfer processes. Thixotropic formulations maintain dot shape after dispensing for controlled bond line thickness.
Multi-Step Assembly
SiP assembly involves multiple cure steps. COFA adhesives are designed with staged cure profiles — B-stage capability for die attach, followed by full cure after wire bonding or flip chip reflow. This prevents material degradation during subsequent thermal steps.
Substrate Compatibility
Validated on organic (BT, ABF), ceramic (LTCC, HTCC), and flexible (polyimide) substrates with standard surface finishes (ENIG, OSP, Cu).
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