About this document
This Technical Note addresses the thermal exposure that arises when a logic die is bonded in an Intel EMIB-T package. It describes a process that keeps bonding pressure in place while moving heat generation to the joints, and proposes a joint feasibility program with Intel. The attached Technical Note is in English.
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Summary
In EMIB-T, heat from the TCB head passes through the logic die to reach the joints, so the expansion mismatch between the silicon bridge and the organic substrate is left behind as stress and warpage. Light at 1470 nm passes through silicon and turns into heat in an absorber on the bond side. The note proposes a process that heats the whole logic bond array in one exposure under a transparent pressure head, together with a joint validation program.
Conclusion
When a logic die is attached by thermocompression bonding (TCB), the heated head raises the temperature of the whole die to deliver heat to the joints. In packages such as Intel EMIB-T, where a silicon bridge is embedded in an organic substrate, silicon and organic materials expand differently, and under constraint that mismatch becomes stress. The resulting warpage and local displacement complicate fine-pitch contact and alignment. The approach keeps the pressure and changes where heat is generated. At 1470 nm the photon energy is 0.843 eV, below the silicon bandgap of about 1.12 eV, so the light passes through silicon to an absorber on the bond side and turns into heat there, which conducts over a short path into the joint. Optical transmission, metal shadowing and absorber distribution are the design inputs. An area light source heats all logic joints in a single exposure while the neighboring HBM stays outside the irradiation field. The transparent Thermal Clutch head serves three functions at once: it transmits the 1470 nm field across the logic footprint, applies a flat, evenly distributed load to keep joint contact and alignment, and provides a controlled thermal path out of the die through its contact conductance and heat capacity. During irradiation it preserves the bond thermal window; after irradiation it holds pressure while the assembly cools. The benefits in the document are targets: lower mismatch loading around the bridge, more stable joint contact during bonding, less thermal disturbance of parts already assembled and a shorter thermal portion of the assembly cycle, each to be measured against the current TCB process on the same test vehicle. The comparison uses three arms (baseline TCB, 1470 nm area bonding, and area bonding with the Thermal Clutch head) and tracks joint quality (daisy-chain resistance, cross-section and voiding, mechanical strength), thermal exposure (logic and substrate temperature history, time above material limits, neighboring HBM temperature) and mechanical response (in-process warpage, local joint displacement, post-bond residual shape). The first application is attaching the logic die to the EMIB-T package substrate, with the light source and head matched to the logic footprint and the heat conducted toward the HBM and embedded bridge monitored. HBM attachment is left as a separate optical-access design task. The document closes by proposing a joint EMIB-T feasibility program. Intel would provide a representative stackup and bump map, baseline TCB conditions and joint-quality and warpage limits; Cools would contribute the 1470 nm area illumination concept, the transparent Thermal Clutch head and the integrated optical and pressure process. The first deliverable is an instrumented logic-bonding coupon with matched joint quality, compared thermal histories and measured warpage.
Topics
- Packaging
- Thermal control
