Cooling stage for cooling down a heated carrier
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Solution Overview
Problem
In high-volume chip bond solder processes, there is a conflict between high equipment throughput and low cooling rate requirements to prevent die cracks, as existing cooling stages are product-specific and require lengthy cooling times due to varying thermal expansion coefficients between semiconductor chips and metal lead-frames.
Innovation Solution
A cooling stage design that relies predominantly on thermal convection between the heated carrier and a cooling body, using adjustable supporting members and a temperature-controlled cooling unit to maintain consistent process settings, reducing dependency on carrier type and allowing for variable spacing to control cooling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low cooling rate is used to prevent die cracks, then the reliability of the semiconductor chip is improved, but the productivity of the equipment deteriorates due to longer cooling times
Solution Approach 1:
The cooling stage applies different cooling conditions to different regions of the carrier. The cooling body is positioned at a specific distance from the carrier surface, creating localized convection zones that provide uniform cooling across the carrier surface. This localized approach ensures consistent cooling rates throughout the carrier, preventing die cracks while maintaining efficient throughput.
Solution Approach 2:
The invention controls the cooling rate by adjusting physical parameters such as the distance between the cooling body and carrier surface, the thermal conductivity of supporting members, and the temperature of the cooling body. By changing these parameters, the system achieves the required low cooling rate for reliability while optimizing the cooling time for productivity.
2Reliability
If different cooling rates are used for different lead-frame types, then the reliability of cooling is improved, but the device complexity increases due to product-specific settings
Solution Approach 1:
The cooling stage is designed with universal applicability to different lead-frame types. The supporting members can be adjusted in position and configuration, and the cooling body temperature can be modified, allowing the same cooling stage to handle various carrier materials and designs without requiring fundamentally different cooling mechanisms. This reduces device complexity while maintaining reliable cooling rate control.
Solution Approach 2:
The cooling stage incorporates adjustable and dynamic elements such as movable supporting members and controllable cooling body temperature. These dynamic features allow the system to adapt to different lead-frame types and cooling rate requirements without increasing fundamental device complexity, as the same structure can be reconfigured for different products.
3Use of energy by moving object
If thermal conduction through mechanical construction is used for cooling, then the cooling efficiency is improved, but the adaptability to different carrier types deteriorates
Solution Approach 1:
The invention introduces thermal convection as an intermediary cooling mechanism between the carrier and the cooling body. By using convection through the air gap or medium between the carrier surface and cooling body, the system achieves efficient heat transfer without direct mechanical contact. This intermediary approach maintains high cooling efficiency while improving adaptability to different carrier types, as the convection mechanism is less sensitive to carrier material properties than direct conduction.
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 approach enables a more uniform and efficient cooling process across different carrier types, reducing the need for extensive reconfiguration and shortening cooling times while maintaining control over cooling rates to prevent die cracks.
Implementation Method 1
cooling of the heated carrier is predominantly obtained through thermal convection between the heated carrier and the cooling body
Implementation Method 2
The thermal conductivity of the plurality of supporting members, the thermal conductivity of the cooling body, the temperature of the cooling body, and the spacing between the cooling body and the heated carrier is configured
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Aspects of the present disclosure relate to a cooling stage for cooling down a heated carrier on which a plurality of components has been mounted. Further aspects of the present disclosure relate to a pick-and-place apparatus that comprises such cooling stage and to a method for cooling down a heated carrier on which a plurality of components has been mounted. The cooling stage according to an aspect of the present disclosure uses supporting members for keeping the heated carrier separated from a cooling body. By relying on thermal convection between the heated carrier and the cooling body, dependency of the cooling stage on the type of carrier used is reduced compared to known cooling stages. For example, for different types of carries, it generally suffices to use different supporting members, e.g. having a different height, and/or to use a different temperature of the cooling body.