Composite Back Plate and Bolster Structure for LGA Package Retention

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Solution Overview

Problem

Future generations of silicon chip manufacturing technology will drive higher performance semiconductor chips with increased transistor packing densities, leading to higher heat dissipation and more I/Os, which poses packaging challenges due to increased loading forces and the risk of chip packages "popping off" connectors.

Innovation Solution

The introduction of improved bolster plate designs with inner support arms that create smaller open spaces, increasing the deformation threshold, and the use of multilayer back plates with harder outer layers and softer inner layers to enhance stiffness without increasing thickness, thereby addressing warping and deformation issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If higher transistor packing densities are used to increase performance, then computing performance is improved, but heat dissipation increases and packaging challenges arise

Engineering Contradiction:

Improvecomputing performanceVSAvoidheat dissipation

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The bolster plate is segmented into multiple regions with different structural characteristics - inner support arms create smaller open spaces in high-stress areas while maintaining larger open spaces in other areas. This segmentation allows the plate to provide enhanced support where needed without uniformly increasing complexity across the entire structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The back plate uses a composite structure with a stiffener layer having different material properties than the base plate. The stiffener layer is positioned to provide targeted reinforcement in areas experiencing high thermal and mechanical stress, allowing the system to manage heat dissipation and loading forces effectively.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If more I/Os are added to chip packages, then functionality is improved, but the risk of packages popping off connectors increases

Engineering Contradiction:

ImproveI/O functionalityVSAvoidpackage retention

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The bolster plate structure is designed in advance with inner support arms positioned to prevent deformation before it occurs. The rigid support arms are pre-configured to counteract the popping forces that will be generated by additional I/Os, ensuring package retention is maintained as functionality increases.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If bolster plate open spaces are made larger to accommodate connectors, then ease of assembly is improved, but deformation resistance deteriorates

Engineering Contradiction:

Improveassembly easeVSAvoiddeformation resistance

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The bolster plate exhibits local quality variations through its inner support arms, which create regions of different structural properties. Areas with smaller open spaces have higher deformation resistance, while other areas maintain larger open spaces for connector accommodation. This local differentiation allows the plate to satisfy both assembly ease and strength requirements in different locations.

Inventive Principle:

Principle #3Local quality

4Stability of the object's composition

If back plate thickness is increased to reduce warping, then stiffness is improved, but device complexity increases

Engineering Contradiction:

Improvewarping resistanceVSAvoidplate structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Instead of increasing thickness in the vertical dimension, the solution adds structural complexity in the planar dimension through the stiffener layer. This approach provides the necessary stiffness and warping resistance by distributing stresses across a broader area rather than concentrating material in the thickness direction, thereby avoiding increased device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12279395B2Patterned bolster plate and composite back plate for semiconductor chip LGA package and cooling assembly retention

Publication Date: 2025.04.15 INTEL CORP

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.