Flip-Chip Module Chip Replacement via Solder Extraction
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Solution Overview
Problem
Existing flip-chip modules do not allow for the reliable replacement of semiconductor chips, leading to waste of entire modules due to the inability to separate and reattach chips without solder residue, which causes uneven contact points and mechanical weakness from low k passivation materials.
Innovation Solution
A method involving heating the solder connections above the flow point, pressing the semiconductor chip and substrate together to remove solder from the contact areas, and then replacing the chip, ensuring no solder residue impedes reattachment, using contact posts with end faces that completely cover the contact points to facilitate smooth reconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flip-chip modules use solder material alone for contact elements, then the structure is simple, but the risk of short circuit between adjacent contact points increases and reliability decreases
Solution Approach 1:
The contact elements use a composite structure combining solder material with a support structure (copper portion and nickel portion). The solder material provides electrical connection while the support structure provides mechanical stability and prevents short circuits between adjacent contact points, resolving the contradiction between simplicity and reliability.
2Productivity
If contact points are disposed in a fine pitch grid of less than 100 μm, then the connection density increases and productivity improves, but the risk of short circuit increases and manufacturing precision becomes more difficult
Solution Approach 1:
The composite contact structure with distinct solder portion and support structure allows for finer pitch spacing while maintaining manufacturing precision. The support structure provides a stable foundation that enables precise positioning of contact points at distances less than 100 μm without increasing short circuit risk.
3Reliability
If low k passivation materials are used for strip conductors, then the signal transmission performance improves, but the mechanical strength decreases and the passivation layer becomes susceptible to cracks and fractures
Solution Approach 1:
The patent provides compensatory measures in advance by designing the contact structure and module assembly to accommodate the mechanical weakness of low k passivation materials. The robust contact structure with support portions compensates for the fragile passivation layer, allowing the module to withstand mechanical tensions without cracking the passivation while maintaining signal transmission performance.
4Ease of manufacture
If the entire flip-chip module is discarded when a single chip fails, then the replacement process is simple, but the loss of substance increases and waste occurs
Solution Approach 1:
The patent enables segmentation of the semiconductor chip from the substrate by providing a method to separate the solder connection. This allows the functional substrate to be reused with a replacement chip, transforming the module from a non-separable unit into separable components, thereby reducing waste while maintaining replacement simplicity.
5Productivity
If solder is not completely removed from contact points during chip replacement, then the replacement process is faster, but the contact point integrity deteriorates and reattachment becomes unreliable
Solution Approach 1:
The patent emphasizes the extraction of solder material from the contact interface during the chip replacement process. By completely removing the solder connection, the contact points on the substrate are restored to their original state, ensuring integrity and reliability for reattachment while maintaining an efficient replacement process.
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
Enables the simple and reliable replacement of semiconductor chips in flip-chip modules, maintaining contact point integrity and allowing for unit testing of modules rather than individual chips, reducing waste and testing costs.
Implementation Method 1
heating of the existing soldered connections above the flow point
Data Source
AI summary
A process for replacing a semiconductor chip of such a flip-chip module and a suitable flip-chip module and an apparatus for implementing the method are disclosed. The flip-chip module comprises at least one semiconductor chip and a substrate. The semiconductor chip comprises contact posts on a surface that are disposed at right angles to the surface. With these contact posts it is connected with contact points of the substrate via a soldered connection. The contact posts completely cover the contact points with their end faces. Due to this it is possible to completely press the solder between the contact posts and contact points out of the intermediate area between the contact points and the contact posts after a renewed heating. This permits a renewed attachment of a further semiconductor chip.