Copper Post Protection via Photoimageable Dielectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional integrated circuit packages with copper posts face issues of cracking or breaking during manufacturing, leading to low yield and high reliability test failure risks, and existing protective schemes like epoxy flux are costly and ineffective.
Innovation Solution
The use of a dielectric material, such as photoimageable dielectric (PID), is applied to surround and protect the copper posts, providing mechanical support and electrical connections while allowing for tighter interposer pitches and smaller package sizes through the creation of openings for integrated circuit dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper posts are provided directly on conductive contacts without protection, then the manufacturing process is simple and cost-effective, but the copper posts crack or break during manufacturing leading to low yield and high reliability test failure
Solution Approach 1:
A dielectric material is introduced as an intermediary substance that surrounds and protects the copper posts. This dielectric layer acts as a mediator between the copper posts and the external environment, preventing direct mechanical stress and damage to the copper posts while maintaining electrical isolation. The dielectric material fills the spaces around the copper posts and provides a protective barrier during manufacturing processes.
Solution Approach 2:
The dielectric material is applied in advance to surround and cushion the copper posts before they are subjected to manufacturing stresses. This protective layer is formed beforehand to prevent cracking and breaking during subsequent assembly and manufacturing processes, rather than attempting to repair damage after it occurs.
2Reliability
If epoxy flux is used to fill the entire interior space to protect copper posts, then the copper posts are protected, but the manufacturing process becomes expensive and yield improvement is still limited
Solution Approach 1:
Instead of filling the entire interior space with protective material, the dielectric is applied locally around the copper posts where protection is actually needed. This localized approach provides sufficient protection for the copper posts while avoiding the excessive material usage and processing complexity of complete interior filling with epoxy flux.
Solution Approach 2:
The dielectric material provides a cost-effective protective solution compared to expensive epoxy flux filling processes. The dielectric layer serves its protective function during manufacturing and can be removed or left in place depending on the specific application requirements, offering a more economical approach to copper post protection.
3Strength
If copper posts are the only mechanical support for the top substrate, then the package structure is simple, but the copper posts are prone to cracking or breaking under mechanical stress
Solution Approach 1:
The mechanical support structure is transformed from pure copper posts to a composite system consisting of copper posts surrounded by dielectric material. This composite structure combines the electrical conductivity and mechanical strength of copper with the protective and structural properties of the dielectric, creating a more robust support system that distributes mechanical stresses more effectively.
Data Source
AI summary
An integrated circuit package includes a substrate/interposer assembly having a plurality of conductive contacts and a plurality of conductive posts, such as copper posts, electrically coupled to at least some of the conductive contacts in the substrate/interposer assembly. The conductive posts are surrounded by a protective dielectric, such as a photoimageable dielectric (PID). An integrated circuit die may be disposed on the substrate/interposer assembly within an interior space surrounded by the dielectric. An additional integrated circuit die may be provided in a package-on-package (POP) configuration.