Interposer Brick Vias for Void-Free Circuit Package Encapsulation
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Solution Overview
Problem
Existing top-side cooled circuit packages face issues with molding compound voids forming underneath interposer bricks, leading to solder bead shorts during the solder paste reflow process due to trapped air and imperfect compound flow, resulting in defective packages.
Innovation Solution
Incorporating a second set of vias in the interposer bricks that are filled with a different material than the first set, providing exit paths for trapped substances like air, gas, and flux, preventing mold voids and ensuring complete encapsulation during the solder reflow process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of vias is used in the interposer brick, then the structure is simple, but molding compound voids form underneath the brick due to trapped air
Solution Approach 1:
The via structure is segmented into two distinct sets: a first set of vias for electrical connections and a second set of vias for substance evacuation. This segmentation allows each set to serve its specific function independently, resolving the contradiction by adding functional complexity only where necessary while maintaining overall structural organization.
Solution Approach 2:
The second set of vias acts as an intermediary pathway that mediates between the trapped substances (air, flux) and the external environment. These vias provide a dedicated escape route that does not interfere with the electrical function of the first set of vias, thereby improving encapsulation quality without compromising electrical connectivity.
2Reliability
If the brick is fully encapsulated with molding compound, then electrical connections are protected, but trapped air causes voids and solder bead shorts
Solution Approach 1:
The harmful trapped substances (air, flux) are extracted from the encapsulation process through the second set of vias. By providing dedicated evacuation pathways, the harmful factors are removed before the molding compound fully solidifies, preventing void formation and subsequent solder bead shorts while maintaining full encapsulation protection.
Solution Approach 2:
The trapped air and flux, which would normally cause defects, are converted into a beneficial evacuation flow through the second set of vias. The pressure differential created during molding actually drives the trapped substances out through the evacuation vias, transforming a potential harm into a self-cleaning mechanism that improves encapsulation quality.
3Reliability
If solder paste is applied over the brick, then electrical connections are established, but trapped substances cause solder bead shorts
Solution Approach 1:
The second set of vias performs preliminary action by evacuating trapped substances (air, flux) before the solder paste reflow process. By clearing the evacuation pathways in advance, the solder paste can be applied and reflowed without risk of trapped substances causing bead shorts, thereby ensuring reliable solder connections.
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
The solution effectively prevents solder bead shorts by expelling trapped substances through the additional vias, ensuring reliable electrical connections and improved thermal performance in high-powered RF products.
Implementation Method 1
the substance is pushed into the second set of vias by the molding compound during encapsulation
Implementation Method 2
a first end of the first material is configured to be electrically coupled to the circuit; wherein a second end of the material is configured to form an electrical terminal
Data Source
AI summary
One example discloses a circuit package, including: wherein the circuit package is configured to include a circuit; a brick having a first set of vias and a second set of vias; wherein the first set of vias are configured to be filled with a first material; wherein a first end of the first material is configured to be electrically coupled to the circuit; wherein a second end of the material is configured to form an electrical terminal on an external surface of the circuit package; and wherein the second set of vias are configured to be filled with a second material different from the first material.