Semiconductor Package Via Formation Without Laser Resin Smear
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Solution Overview
Problem
Existing semiconductor package technologies face challenges in achieving high connection reliability and narrow pitch between solder balls due to difficulties in forming vias in thick molding resin layers using laser beam hole-forming processes, which results in resin smear and unreliable solder connections.
Innovation Solution
A method involving a support plate with a mounting portion and a circuit substrate with connection pads, where a truncated-cone-shaped solder layer is formed between the support plate and the substrate, and the support plate is removed to create a via in the resin layer, allowing for a reflow process to form a spherical solder layer, eliminating the need for laser work and reducing resin smear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam hole-forming process is used to form vias in thick molding resin layers, then vias can be formed to expose solder balls, but the working period of time becomes long and the laser work becomes difficult
Solution Approach 1:
The patent extracts the solder ball exposure function from the laser hole-forming process. Instead of using laser to remove resin, the invention forms vias through mechanical or chemical means that expose the solder ball upper surface more efficiently, eliminating the time-consuming laser work while achieving the same functional result of solder ball exposure for subsequent connection processes
Solution Approach 2:
The patent replaces the laser beam (optical/thermal system) with a mechanical or chemical via formation process. The via formation is achieved through methods such as drilling or etching that are more time-efficient for thick resin layers, substituting the laser-based approach with a more suitable mechanical or chemical process for the specific application
2Manufacturing precision
If laser work is used to form vias with conical and tapered shape, then vias can be formed in resin layers, but the diameter is enlarged on the upper side and the vias adjacent to each other interfere with each other, making it difficult to narrow the pitch between solder balls
Solution Approach 1:
The patent applies local quality by creating vias with uniform cylindrical shape rather than conical taper. The via diameter remains consistent along the length, allowing adjacent vias to be positioned closer together without interference. This local geometric optimization enables narrower pitch between solder balls while maintaining via integrity and function
Solution Approach 2:
Instead of accepting the conical shape as a natural result of laser processing, the invention inverts the approach by using mechanical or chemical methods that produce cylindrical vias. This reverses the geometric outcome from tapered to uniform, solving the interference problem between adjacent vias and enabling tighter spacing
3Manufacturing precision
If the via is formed by removing the molding resin layer with the laser work, then vias can be formed, but it is very difficult to completely remove a resin component which becomes smear, from the surface of the solder ball
Solution Approach 1:
The patent converts the harmful resin smear problem into a benefit by using a via formation process that does not generate smear. The mechanical or chemical method used to form vias cleanly exposes the solder ball surface without leaving residual resin components, transforming the situation from one where smear compromises reliability to one where the surface remains clean and ready for reliable solder connections
Solution Approach 2:
The invention introduces an intermediary process step between via formation and solder connection that ensures complete removal of resin components. The mechanical or chemical via formation method acts as an intermediary that cleanly separates the via from the surrounding resin without creating smear, facilitating reliable subsequent soldering operations
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 method enables high connection reliability and flexible pitch adjustment between solder balls, achieving a POP structure at a lower cost without the challenges of laser-based via formation, ensuring reliable electrical connections between semiconductor packages.
Implementation Method 1
performing a reflow process, whereby the truncated-cone-shaped solder layer is formed into a spherical solder layer within the via
Data Source
AI summary
A circuit substrate having a mounting surface on which a semiconductor chip is mounted and at least one connection pad formed on the mounting surface is connected to a support plate having at least one mounting portion with a diameter larger than a diameter of the connection pad, through a truncated-cone-shaped solder layer which is formed from at least one solder ball on the basis of a difference between the diameter of the mounting portion and the diameter of the connection pad.