Staggered PCB Memory Layout for Solder Ball Reliability
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Solution Overview
Problem
Semiconductor packages mounted on both sides of a printed circuit board (PCB) often warp due to thermal expansion mismatches and mechanical stress, leading to strain energy density issues in solder balls that can result in cracking, breaking, or separation from the PCB.
Innovation Solution
The semiconductor devices are mounted on opposed surfaces of a pliable PCB in a staggered or partially overlapping configuration, allowing the PCB to flex and maintain contact with warped semiconductor devices, thereby reducing strain energy density in solder balls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If semiconductor packages are mounted aligned on both top and bottom surfaces of PCB to maximize storage capacity, then storage capacity is improved, but solder ball reliability deteriorates due to warping-induced strain energy density
Solution Approach 1:
The patent applies asymmetry by staggering the semiconductor packages on opposite surfaces of the PCB so that they are offset from each other rather than aligned. This asymmetric arrangement allows the PCB to warp without creating concentrated strain energy density in the solder balls, as the warping forces are distributed across different locations. The staggered configuration maintains high storage capacity while preventing solder ball failure.
2Stability of the object's composition
If semiconductor packages are rigidly mounted on PCB to maintain structural stability, then structural stability is improved, but warping-induced strain energy density in solder balls increases
Solution Approach 1:
The patent applies dynamics by allowing the PCB to flex and warp dynamically in response to thermal and mechanical stresses. The staggered package arrangement creates a flexible system where the PCB can adjust its shape to accommodate warping without creating excessive strain energy density in the solder balls. This dynamic adaptation maintains both structural stability and solder ball reliability.
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 approach prevents cracking, breaking, or separation of solder balls from the PCB by maintaining strain energy density below a predefined threshold, enhancing board-level reliability and allowing for higher thermal cycle life.
Implementation Method 1
a pliable printed circuit board (PCB) having semiconductor devices mounted by solder balls on first and second opposed major surfaces... the PCB flexes to maintain contact with the warped semiconductor devices and to reduce the strain energy density in the soldered connections
Implementation Method 2
semiconductor packages often warp when they are mounted on a printed circuit board (PCB) due to a number of factors, including a mismatch of the coefficients of thermal expansion (CTE) of the materials used in the semiconductor package and PCB, respectively, the temperature at which the package is soldered to the PCB
Data Source
AI summary
A semiconductor storage device such as an SSD includes a pliable printed circuit board (PCB) having semiconductor memory devices mounted by solder balls on first and second opposed major surfaces. The memory devices are mounted so as to be staggered and/or partially overlapping with each other on the first and second surfaces of the PCB in at least one direction. The staggered arrangement allows the PCB to flex upon warping of the memory devices mounted on the PCB.