Composite Back Plate and Bolster Arms for LGA Warping Resistance
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Solution Overview
Problem
The increasing transistor packing densities and corresponding heat dissipation in future semiconductor chips, combined with higher I/O counts, lead to packaging challenges such as the propensity for chip packages to 'pop off' connectors due to increased loading forces, which traditional bolster plates struggle to address effectively.
Innovation Solution
The introduction of bolster plates with inner support arms and composite back plates using multiple layers of materials with varying stiffness, including harder materials like tungsten and iridium alloys, to enhance rigidity and prevent warping, along with improved stud integration to secure the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional bolster plates are used, then the structure is simple and easy to manufacture, but the plate warps under high loading forces from increased I/O counts and transistor density
Solution Approach 1:
The bolster plate is divided into multiple segments including a peripheral frame and inner support arms. This segmentation allows each component to contribute to overall structural stability while distributing the loading forces from high-density I/O connections, preventing warping without requiring a completely complex redesign.
Solution Approach 2:
Inner support arms are strategically positioned at specific locations within the bolster plate where loading forces are most concentrated. This local reinforcement approach provides targeted warping resistance exactly where needed, rather than uniformly increasing complexity across the entire plate structure.
2Strength
If harder materials like tungsten and iridium alloys are used in composite back plates, then rigidity and warping prevention are enhanced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The back plate is constructed as a composite structure combining multiple materials including tungsten and iridium alloys with other metals. This composite approach achieves the required rigidity and strength to prevent warping under high loading forces while allowing each material to be utilized in optimal quantities, balancing performance with manufacturability.
Solution Approach 2:
The composite back plate structure employs nested layers where harder materials like tungsten and iridium are strategically positioned within a composite matrix. This nesting arrangement maximizes rigidity where most needed while simplifying manufacturing compared to using solely hard materials throughout the entire structure.
3Stability of the object's composition
If the bolster plate open space is reduced to prevent warping, then structural stability improves, but the area available for connector I/Os decreases
Solution Approach 1:
The bolster plate is segmented into a peripheral frame that defines the outer boundary and inner support arms that provide structural reinforcement. This segmentation allows the plate to maintain large open space for connector I/Os while the distributed support structure prevents warping through strategic reinforcement without reducing the usable area.
Solution Approach 2:
Reinforcement is applied locally through inner support arms positioned specifically where loading forces concentrate, rather than reducing the overall open space. This allows maximum area for connector I/Os while providing targeted warping resistance exactly where the physics of high-density connections require it.
Data Source
AI summary
An apparatus is described. The apparatus includes a back plate, where, an electronic circuit board is to be placed between the back plate and a thermal cooling mass for a semiconductor chip package. The back plate includes a first material and a second material. The first material has greater stiffness than the second material. The back plate further includes at least one of: a third material having greater stiffness than the second material; re-enforcement wires composed of the first material; a plug composed of the second material that is inserted into a first cavity in the first material, a stud inserted into a second cavity in the plug. An improved bolster plate having inner support arms has also been described.