Semiconductor Package Without Chip Carrier Using T-Shaped Metal Studs
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Solution Overview
Problem
Conventional semiconductor packages without chip carriers face issues such as delamination between pads and encapsulant, increased manufacturing costs due to the use of costly metals, and structural instability leading to terminal drop-off and bending, which hinder miniaturization and mass production.
Innovation Solution
A semiconductor package design featuring metal studs with bonding pads forming a T-shaped structure, using a copper layer and anti-oxidant layers like silver or OSP films to enhance bonding with encapsulants, and a fabrication method involving half-etching of a metallic carrier to form grooves and studs, eliminating the need for costly etching resist metals and improving structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pads are formed by etching copper carrier with costly metal etching resist layer, then etching precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive metal etching resist layers (Au, Pd) with a disposable photoresist layer that can be patterned and removed easily. The photoresist serves as a temporary protective layer during etching, eliminating the need for costly precious metals while achieving the required etching precision for forming pads and grooves on the copper carrier.
Solution Approach 2:
The patent changes the material parameter of the etching resist from precious metals (Au, Pd) to organic photoresist material. This parameter change dramatically reduces manufacturing cost while maintaining etching precision through photo lithography patterning, resolving the contradiction between precision and cost.
2Ease of manufacture
If plating layer such as Ni or Ag is used on copper carrier, then manufacturing cost is reduced, but bonding strength with encapsulant deteriorates
Solution Approach 1:
The patent applies different surface treatments to different locations: the copper carrier surface in contact with encapsulant receives a specific surface treatment (oxidation or roughening) to enhance bonding, while other areas may have protective plating. This local differentiation ensures strong bonding where needed without compromising overall manufacturing efficiency.
Solution Approach 2:
The patent creates a composite structure where the copper carrier is combined with surface oxides or conversion coatings that provide both cost-effectiveness and enhanced bonding properties. The composite material system achieves the dual requirement of reduced cost and improved bonding strength with the encapsulant.
3Weight of moving object
If copper carrier thickness is reduced for miniaturization, then package weight is reduced, but structural stability deteriorates
Solution Approach 1:
The patent compensates for reduced copper carrier thickness by adding vertical dimension features such as raised pads and recessed grooves. These three-dimensional structures provide mechanical interlocking with the encapsulant, enhancing structural stability despite the thinner carrier, thus resolving the contradiction between weight reduction and stability.
Solution Approach 2:
The patent introduces curved or rounded features at the interfaces between copper carrier and encapsulant, such as rounded pad edges or curved transition zones. These curved geometries reduce stress concentration and improve bonding interface strength, maintaining structural stability in thin-carrier designs.
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 enhances bonding strength between encapsulants and metal studs, prevents delamination and terminal drop-off, reduces manufacturing costs, and facilitates stable mass production by eliminating the need for costly metals and addressing structural issues.
Implementation Method 1
a part of the metallic carrier is removed by half etching
Implementation Method 2
The grooves are filled with a first encapsulant... bonding pads formed on and electrically connected to the metal studs
Implementation Method 3
At least one of the bonding pads comprises a metal layer... and an anti-oxidant layer that covers the metal layer
Data Source
AI summary
A semiconductor package without a chip carrier formed thereon and a fabrication method thereof. A metallic carrier is half-etched to form a plurality of grooves and metal studs corresponding to the grooves. The grooves are filled with a first encapsulant and a plurality of bonding pads are formed on the metal studs. The first encapsulant is bonded with the metal studs directly. Each of the bonding pads and one of the metal studs corresponding to the bonding pad form a T-shaped structure. Therefore, bonding force between the metal studs and the first encapsulant is enhanced such that delamination is avoided. Die mounting, wire-bonding and molding processes are performed subsequently. Since the half-etched grooves are filled with the first encapsulant, the drawback of having pliable metallic carrier that makes transportation difficult to carry out as encountered in prior techniques is overcome, and the manufacturing cost is educed by not requiring the use of costly metals as an etching resist layer.