Adhesiveless Flexible Tape Substrate for Semiconductor Packaging
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Solution Overview
Problem
The use of adhesives in flexible tape substrates for semiconductor device assembly is challenging due to handling difficulties and adhesive material extrusion during punching, leading to voids and defective plug surfaces, which can result in solder joint cracking during reliability testing.
Innovation Solution
A method and apparatus for fabricating semiconductor devices using an adhesiveless flexible tape substrate, where holes are punched in the substrate with a metal layer attached to a polyimide layer without adhesive, and metal is electro-deposited to plug the holes and increase the metal layer thickness, eliminating the need for adhesive-based lamination and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive material is used to attach metal layer to polyimide layer, then the metal layer can be laminated to the substrate, but the adhesive material is difficult to handle, sticks to processing equipment, and extrudes during punching causing defects
Solution Approach 1:
The patent removes the adhesive layer entirely from the substrate structure. Instead of using adhesive material between the polyimide layer and metal layer, the invention uses a punched hole structure where the metal layer is directly attached to the polyimide layer at the punched locations, eliminating the adhesive material that causes handling difficulties and equipment contamination.
Solution Approach 2:
Rather than applying adhesive and then punching holes through it (conventional approach), the invention inverts the sequence by first punching holes through the polyimide layer and then attaching the metal layer to these punched locations, thereby avoiding adhesive extrusion during the punching operation.
2Strength
If adhesive material is used during punching, then the metal layer can be attached to the substrate, but adhesive material is squeezed into the lumen of punched holes disrupting metal deposition and causing voids
Solution Approach 1:
The patent extracts and eliminates the adhesive material from the substrate construction. By using direct attachment of the metal layer to the polyimide layer at punched locations without any adhesive intermediary, the invention prevents adhesive material from being squeezed into the lumen of punched holes, thereby ensuring clean metal deposition and avoiding voids or defective plug surfaces.
Solution Approach 2:
The invention segments the substrate into distinct functional zones: the polyimide layer with punched holes, and the metal layer attached at specific punched locations. This segmentation allows the metal layer to be precisely positioned and attached only where needed, preventing contamination of the hole lumens and ensuring high-quality metal deposition.
3Strength
If adhesive material is present in punched holes, then the layers can be bonded, but it may result in formation of defects such as notch in solder ball and solder joint cracking
Solution Approach 1:
The patent completely removes the adhesive material from the substrate structure and eliminates its presence in punched holes. By using direct attachment of the metal layer to the polyimide layer without adhesive, the invention prevents the formation of defects such as notches in solder balls and solder joint cracking, thereby significantly improving the reliability of solder joints during reliability testing.
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 fabrication process, reduces voids and defective plug formation, enhances semiconductor package reliability by eliminating adhesive-related defects, and allows for selective metal deposition using electroforming, increasing the metal layer thickness from less than 2 microns to tens of microns.
Implementation Method 1
A metal is deposited on the cover exposed at the base of the hole, the metal being used to form a bond with the metal layer. The metal being deposited causes the hole to be plugged up to a selective height.
Implementation Method 2
The adhesiveless fabrication technique also uses electroforming for electro deposition of metal on selective areas of the flexible tape substrate.
Data Source
AI summary
In a method and apparatus for fabricating a semiconductor device having a flexible tape substrate, a hole is punched in the flexible tape substrate. The flexible tape substrate includes a metal layer attached to a polyimide layer without an adhesive there between. A cover is placed on the metal layer to cap a base of the hole. A metal is deposited on the cover exposed at the base of the hole, the metal being used to form a bond with the metal layer. The metal being deposited causes the hole to be plugged up to a selective height. Upon removal of the cover, the metal may also be deposited on the metal layer to increase a thickness of the metal layer.