Spacer System for Interposer Warpage Control
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Solution Overview
Problem
The manufacturing of microelectronic assemblies, particularly the attachment of interposers to PCBs, is complicated by the need for hybrid technologies and expertise, leading to increased costs and reduced yield due to the use of handle wafers, which are fragile and prone to warpage, limiting manufacturing independence and flexibility.
Innovation Solution
A spacer system that holds the interposer from the bumped side without adhesive, using vacuum or electrostatic forces to support the interposer during attachment and processing, allowing for independent manufacturing stages without the need for handle wafers, enabling flexible and cost-effective assembly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a thin interposer is used to reduce vertical extent and improve circuit speed, then parasitic inductances and capacitances are reduced, but the interposer becomes fragile and cannot absorb much heat during manufacturing
Solution Approach 1:
A handle wafer is introduced as an intermediary component between the thin interposer and the manufacturing equipment. The handle wafer provides mechanical support during fabrication and assembly processes, enabling the thin interposer to maintain its low-parasitic characteristics while the handle absorbs mechanical stresses and thermal loads during manufacturing.
2Length of moving object
If a thin interposer is used to reduce vertical extent, then interconnect length is reduced, but the interposer is easily warped making attachment difficult
Solution Approach 1:
The handle wafer serves as a mediator that mechanically supports the thin interposer during assembly, preventing warpage-induced alignment issues. By providing a rigid backing, the handle ensures that solder balls remain at consistent heights and that the interposer maintains its shape during the attachment process to the PCB.
Solution Approach 2:
The handle wafer is attached to the interposer before the interposer is thinned to its final dimensions. This preliminary support structure prevents warpage from developing during subsequent processing steps, allowing the interposer to be manufactured at its final thin profile without experiencing shape distortion during critical assembly operations.
3Reliability
If a handle wafer is used to strengthen the interposer, then manufacturing reliability is improved, but bonding and debonding complicate the manufacturing process
Solution Approach 1:
The handle wafer is designed as a temporary intermediary that is easily attached and removed. By using a simple adhesive bonding method that requires no complex processing conditions, the handle provides necessary mechanical support during manufacturing while allowing for straightforward removal after the interposer is fully assembled, minimizing added process complexity.
4Adaptability or versatility
If hybrid technologies are used to assemble ICs with interposers and PCBs, then manufacturing flexibility is improved, but costs increase and yield is reduced
Solution Approach 1:
The handle wafer is designed to work with various interposer types, sizes, and materials, providing universal support during manufacturing. This single handle design can be used across different product lines and manufacturing scenarios, allowing the same handling and assembly equipment to process diverse interposer configurations without requiring specialized tools or procedures for each case.
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 simplifies the manufacturing process by eliminating the complexity of handle wafers, reducing warpage issues, and allowing for independent expertise and equipment usage across different manufacturing stages, thereby enhancing manufacturing flexibility and cost efficiency.
Implementation Method 1
A vacuum holder is used to hold the spacer in position
Implementation Method 2
using vacuum or electrostatic forces to support the interposer during attachment and processing
Data Source
AI summary
A workpiece (120) has protruding conductive features (140) at least on a first side. The second side is processed while the workpiece is held from the first side by a holder (220H). To prevent damage to the protruding features and flatten the workpiece (which could be otherwise warped), a spacer (210) is inserted between the workpiece and the holder. The spacer has holes (250) receiving the protruding features. The workpiece can be held by forces generated by the holder such as vacuum or an electrostatic force, without an adhesive. Other features and advantages are provided.