Semiconductor Package Solder Ball Alignment via Pre-Molding Placement
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Solution Overview
Problem
The challenge in semiconductor package manufacturing lies in accurately planting solder balls on a package substrate with a large number of input/output connections, exacerbated by warpage and shrinkage issues post-molding, which affect the bonding pad alignment and lead to low yield rates due to solder ball misalignment or falling off.
Innovation Solution
The solution involves forming electrical connecting elements and seed layers before the molding process, ensuring alignment with bonding pads and preventing warpage by using a carrier with a higher Young's modulus than the passivation layer and molding compound, thus maintaining the substrate structure's position during packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the bonding pad density is increased to accommodate a large number of I/O connections, then the package size can be kept small, but the difficulty of solder ball planting increases due to alignment precision requirements
Solution Approach 1:
The patent performs solder ball planting on the package substrate before the molding process, when the substrate is still flat and stable. This preliminary action allows precise alignment of solder balls with bonding pads at high density without the warpage issues that would occur after molding, thereby maintaining small package size while achieving required manufacturing precision.
2Stability of the object's composition
If the molding process is performed before solder ball planting, then the package structure is formed, but warpage and shrinkage occur making subsequent solder ball planting difficult
Solution Approach 1:
The patent reverses the conventional sequence by performing solder ball planting before molding. This preliminary action is taken when the package substrate is in its flat, stable state, allowing precise solder ball placement. After molding causes warpage and shrinkage, the pre-planted solder balls remain properly aligned because they were positioned on the flat substrate before deformation occurred.
3Manufacturing precision
If the bonding pad size is enlarged to facilitate solder ball planting, then alignment accuracy improves, but the package size increases
Solution Approach 1:
The patent performs solder ball planting before the molding process when the substrate is flat and stable, allowing precise alignment without needing enlarged bonding pads. This approach achieves high alignment accuracy through the stable substrate condition rather than through increased pad size, thereby maintaining compact package dimensions.
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 improves the yield rate of solder ball bonding by maintaining the substrate's position and preventing delamination, allowing for precise alignment and reliable attachment of solder balls without the need for enlarged bonding pads, thereby enhancing the packaging process's accuracy and efficiency.
Implementation Method 1
using a carrier with a higher Young's modulus than the passivation layer and molding compound, thus maintaining the substrate structure's position during packaging
Data Source
AI summary
An electronic device includes an insulating layer, a metal layer and at least one electrical connecting element. The insulating layer has a top surface and a bottom surface opposite to the top surface, and defines an opening extending between the top surface and the bottom surface. The metal layer is disposed in the opening of the insulating layer and has a top surface and a bottom surface opposite to the top surface. The bottom surface of the metal layer is substantially coplanar with the bottom surface of the insulating layer. The electrical connecting element is attached to the bottom surface of the metal layer through a seed layer.