Solder Reinforcement Structure for Semiconductor Substrate Warping
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Solution Overview
Problem
Conventional semiconductor chip package substrates tend to warp due to mismatches in coefficients of thermal expansion, leading to electrical pathway issues and potential damage, which complicates the reduction of electrical pathways to lower power supply inductance and improve power fidelity.
Innovation Solution
A solder reinforcement structure is formed on the package substrate outside the central area to resist bending, comprising a solder-wettable surface with a solder mask and deposited solder, which acts as a reinforcement member to counteract warping and provide connection points for passive devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical pathways in the substrate are shortened to lower power supply inductance and improve power fidelity, then power fidelity is improved, but substrate warping due to thermal expansion mismatch becomes more difficult to control
Solution Approach 1:
The patent applies local quality by placing reinforcement structures (such as stiffener rings or additional core layers) only in specific regions of the substrate where warping occurs, rather than uniformly throughout. This allows the substrate to maintain short electrical pathways for improved power fidelity while locally reinforcing areas prone to warping due to thermal expansion mismatch.
Solution Approach 2:
The patent employs composite materials by combining multiple layers with different thermal expansion coefficients (e.g., alternating layers of ceramic and metal, or glass-filled epoxy with metal traces) to create a substrate that is inherently more resistant to warping. This composite structure allows short electrical pathways to be maintained while the layered construction compensates for thermal stress.
2Strength
If conventional stiffener rings are mounted to the substrate to increase stiffness, then substrate stiffness is improved, but additional adhesive layers and mounting complexity are introduced
Solution Approach 1:
The patent merges the reinforcement function directly into the substrate structure by integrating stiffener rings as part of the substrate manufacturing process itself, rather than mounting them separately. This integration eliminates the need for additional adhesive layers and reduces mounting complexity while maintaining the stiffness-enhancing benefit.
Solution Approach 2:
The patent applies preliminary action by pre-forming reinforcement structures (such as embedded stiffener rings or reinforced core layers) during substrate manufacturing before final assembly. This allows the stiffness reinforcement to be built-in advance, eliminating subsequent mounting steps and reducing overall device complexity.
3Strength
If the substrate core layers are increased to provide more stiffness, then substrate stiffness is improved, but the overall substrate thickness and electrical pathway length increase
Solution Approach 1:
The patent applies local quality by strategically placing thicker or reinforced core layers only in regions where structural support is needed (such as under stiffener rings or in high-stress areas), rather than uniformly increasing the entire substrate thickness. This localized reinforcement maintains overall substrate stiffness while keeping electrical pathway lengths short in critical signal regions.
Solution Approach 2:
The patent resolves this contradiction by moving the stiffness-enhancing mass to a different dimension - placing reinforcement structures (like stiffener rings or embedded cores) in the lateral dimension rather than uniformly increasing vertical thickness. This allows the substrate to achieve required stiffness without proportionally increasing the vertical distance that electrical pathways must traverse.
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 reinforcement structure effectively reduces substrate warping, improves mounting accuracy, and enhances power fidelity by maintaining shorter electrical pathways without inducing additional stress on the substrate.
Implementation Method 1
mismatches in the coefficients of thermal expansion for the chip, underfill and substrate
Implementation Method 2
A solder-wettable surface is formed on the first side outside the central area
Data Source
AI summary
Various semiconductor chip package substrates with reinforcement and methods of making the same are disclosed. In one aspect, a method of manufacturing is provided that includes providing a package substrate that has a first side and a second side opposite to the first side. The first side has a central area adapted to receive a semiconductor chip. A solder reinforcement structure is formed on the first side of the package substrate outside of the central area to resist bending of the package substrate.