Package-on-Package Height Reduction via Electrical Arc Connector Trimming
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Solution Overview
Problem
Conventional Package-on-Package (PoP) processes face challenges in efficiently bonding top and bottom packages due to the burial of solder balls under molding compound, requiring complex laser ablation or drilling to expose them, which complicates the bonding process and increases structural height.
Innovation Solution
The method involves applying molding material over the package substrate, exposing electrical connectors, and using an electrical arc to remove the top portions of these connectors, leaving the bottom portions intact, which are then used for bonding the top package, reducing overall height and simplifying the bonding process by using non-reflowable metal balls or solder balls that are easily controlled in size and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are buried in molding compound for protection, then reliability is improved, but device complexity increases due to required laser ablation or drilling to expose them
Solution Approach 1:
The patent applies preliminary action by pre-exposing the solder balls through the molding compound before bonding occurs. The method includes forming openings in the molding compound to expose the solder balls, and positioning the top package over the bottom package with the exposed solder balls visible and accessible. This eliminates the need for complex laser ablation or drilling operations during the bonding process, thereby reducing device complexity while maintaining the protective embedding of solder balls.
2Ease of operation
If laser ablation or drilling is performed to expose solder balls, then ease of operation is improved, but manufacturing precision deteriorates due to potential damage to surrounding structures
Solution Approach 1:
The patent performs the exposure of solder balls as a preliminary action before bonding, using controlled opening formation in the molding compound. By exposing the solder balls in advance through precisely controlled openings, the method avoids the need for aggressive laser ablation or drilling operations that could damage surrounding structures. This preliminary exposure approach maintains manufacturing precision while improving ease of operation during the bonding process.
3Reliability
If conventional bonding process with buried solder balls is used, then reliability is improved, but productivity decreases due to complex bonding steps
Solution Approach 1:
The patent improves productivity by performing preliminary exposure of solder balls through controlled openings in the molding compound before the bonding step. This preliminary action makes the solder balls directly accessible for bonding without requiring complex laser ablation, drilling, or other intricate exposure operations during the bonding process itself. The method maintains bonding reliability through proper exposure and positioning while significantly streamlining the bonding process to enhance manufacturing efficiency and productivity.
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 reduces the overall height of the PoP structure, simplifies the bonding process, and allows for precise control over connector pitch, enhancing manufacturing efficiency and structural integrity.
Implementation Method 1
an electrical arc to remove the top portions of these connectors
Implementation Method 2
an electrical arc to remove the top portions of these connectors
Data Source
AI summary
A package includes a package component, which further includes a top surface and a metal pad at the top surface of the package component. The package further includes a non-reflowable electrical connector over and bonded to the metal pad, and a molding material over the package component. The non-reflowable electrical connector is molded in the molding material and in contact with the molding material. The non-reflowable electrical connector has a top surface lower than a top surface of the molding compound.