Perforated Interposer TIM for Heat Spreader Separation
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Solution Overview
Problem
The increasing power density and operating temperature of semiconductor devices due to miniaturization pose challenges in heat dissipation, particularly in the separation of heat spreaders from VTM arrays without damaging good modules, as existing thermal interface materials (TIMs) either lack compliance or are not mechanically stable enough to accommodate bondline tolerances and tensile stresses.
Innovation Solution
A thermal interface structure comprising a TIM on an interposer that controls the area of contact by using a perforated interposer with holes, allowing the TIM to bond only through specific areas, reducing the total bond area and thus the tensile stress required for separation, enabling safe disassembly and maintaining mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a TIM is used to join heat spreader to VTM array, then heat transfer is improved, but tensile stress during separation damages fragile solder connections
Solution Approach 1:
The patent divides the bonding interface into discrete bonding areas separated by non-bonding gaps. The TIM is applied only in specific regions rather than continuously across the entire interface, creating segmented bonding zones that reduce cumulative tensile stress while maintaining thermal coupling in critical areas.
Solution Approach 2:
The patent applies TIM selectively in specific local regions rather than uniformly across the entire interface. The bonding areas are strategically positioned to provide necessary thermal transfer and mechanical strength, while non-bonding gaps are placed in regions where stress concentration would be problematic, creating local variations in bonding quality.
2Stability of the object's composition
If TIM accommodates large bondline tolerances, then mechanical stability is improved, but separation force becomes too high and damages components
Solution Approach 1:
The bonding interface is segmented into multiple discrete bonding areas rather than a continuous bond. This segmentation allows the structure to accommodate bondline tolerances within each local bonding zone while the gaps between bonding areas prevent stress accumulation across the entire interface, reducing the total separation force required.
3Temperature
If heat spreader is securely attached for heat dissipation, then thermal performance is improved, but rework and module replacement becomes difficult
Solution Approach 1:
The heat spreader attachment is segmented into discrete bonding areas rather than a continuous strong bond. This allows the heat spreader to remain securely attached during operation for effective heat dissipation, while the segmented nature of the bonding enables controlled separation during rework or module replacement without requiring complete bond failure.
Solution Approach 2:
The TIM layer acts as an intermediary between the heat spreader and VTM array, providing thermal coupling during operation while its segmented application pattern creates controlled separation points that facilitate removal during rework. The TIM mediates between the conflicting requirements of secure attachment and ease of separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for the selection of various commercial and newly formulated TIMs, accommodating large bondline tolerances and reducing tensile stresses below the fragility limit of components, ensuring safe separation of heat spreaders without damaging good modules while maintaining low thermal resistance.
Implementation Method 1
thermal interface material (TIM) that not only joined them in a heat exchange relation but also provided sufficient flexibility
Data Source
AI summary
A method comprises applying an adhesive to a first substrate and a second substrate to secure the first substrate to the second substrate. The adhesive extends in a plane on one side of an interposer that also extends in the plane, and is contiguous with the adhesive. The interposer comprises openings to enable flow of adhesive through the openings to form adhesive bond areas on one of the substrates where the areas substantially conform to the openings and lie adjacent to adhesive free areas. The adhesive substantially covers the other of the substrates so that the bond areas produce regions of reduced adhesive strength to the one substrate compared to the bond strength of the adhesive to the other substrate. Adjusting opening sizes adjusts area bond strengths. One substrate may comprise a VTM, the other a heat spreader, and the adhesive, a TIM. An article of manufacture comprises the substrate-adhesive-interposer-adhesive-substrate layers.