Bottom-Side Stiffener for IC Package Warpage and Shock

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Solution Overview

Problem

As integrated circuit (IC) packages increase in size to accommodate higher I/O requirements, they become more susceptible to warpage, and traditional upper-side stiffeners, while reducing compliance, increase the risk of shock-related failures.

Innovation Solution

A bottom-side stiffening element is introduced between the substrate and the circuit board, which reduces warpage, increases shock resistance, and can function as a stand-off or power delivery component, using a material like copper with a rectangular frame shape and varying widths, attached via adhesive or solder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the substrate size is increased to accommodate higher I/O requirements, then the I/O capacity is improved, but the warpage susceptibility increases

Engineering Contradiction:

ImproveI/O capacityVSAvoidsubstrate warpage

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

Instead of placing the stiffener on the conventional upper side of the substrate, this patent inverts the approach by positioning the stiffening element on the bottom side of the substrate. This inverted placement effectively reduces warpage while maintaining substrate integrity and supporting higher I/O capacities without the adverse effects of traditional stiffener placement.

Inventive Principle:

Principle #13The other way round (Inversion)

2Stability of the object's composition

If a stiffener is placed on the upper side of the substrate, then the warpage is reduced, but the shock-related failure risk increases

Engineering Contradiction:

Improvesubstrate warpageVSAvoidshock-related failure risk

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent inverts the conventional stiffener placement from the upper side to the bottom side of the substrate. This inversion maintains the warpage-reduction benefit while eliminating the increased shock-related failure risk associated with upper-side stiffeners, as the bottom-side placement does not interfere with the mechanical compliance needed to absorb shock.

Inventive Principle:

Principle #13The other way round (Inversion)

3Area of stationary object

If the substrate size is increased, then the surface area for interconnects is improved, but the compliance decreases

Engineering Contradiction:

Improvesubstrate surface areaVSAvoidpackage compliance

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

By placing the stiffening element on the bottom side rather than the upper side, the patent maintains substrate compliance necessary for shock absorption while still providing structural support to reduce warpage. This inverted placement allows the substrate to retain its natural flexibility and compliance characteristics even as the substrate size increases to provide greater surface area for interconnects.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8952511B2Integrated circuit package having bottom-side stiffener

Publication Date: 2015.02.10 INTEL CORP

AI summary

Embodiments of a bottom-side stiffening element are disclosed. The stiffening element may be disposed between an integrated circuit package and an underlying circuit board. In some embodiments, the stiffening element is attached to the underlying circuit board. Other embodiments are described and claimed.