Spring-Loaded BGA Connection for Warpage Compensation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current semiconductor device packages face issues with intermittent connections due to non-planar printed wire boards and warpage caused by thermal expansion, leading to potential disconnection and damage during repair or reattachment, especially in applications where repair is not possible.

Innovation Solution

A system and method using flexible springs coupled with a ball grid array (BGA) and spacer plates to secure the BGA to a printed wire board, providing flexibility in the x, y, and z axes to accommodate warpage and maintain connection integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a rigid BGA connection is used to ensure solid electrical connection, then manufacturing precision is improved, but the connection becomes vulnerable to warpage and thermal expansion causing intermittent failures and disconnections

Engineering Contradiction:

Improveconnection precisionVSAvoidconnection reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent replaces the rigid BGA connection with a dynamic spring-loaded mechanism. The springs compress and expand to accommodate board warpage and thermal expansion, maintaining continuous electrical contact. This dynamic adaptation resolves the contradiction by allowing the connection to remain both precise and reliable under varying conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the mechanical parameters of the connection from rigid to flexible by introducing springs with specific force constants and compression ranges. This parameter change allows the connection to adapt to dimensional changes in the PCB while maintaining reliable electrical contact, resolving the contradiction between precision and reliability.

Inventive Principle:

Principle #35Parameter changes

2Ease of repair

If field repair is attempted by removing and reattaching the BGA, then device functionality may be restored, but the risk of damaging the board and permanently disabling the device increases

Engineering Contradiction:

Improvefield repair capabilityVSAvoiddamage risk

Core Design Contradiction:

Ease of repairVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary spring mechanism between the BGA and the PCB that absorbs stress and prevents direct transmission of mechanical forces. This intermediary protects both the board and the device during handling and repair operations, reducing damage risk while maintaining repair capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The spring-loaded connection provides beforehand cushioning by pre-compressing the springs to create a resilient connection. This cushioning effect protects the rigid BGA and PCB traces from impact and stress during field repair operations, reducing the harmful effects of rough handling.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If multiple layers of materials with different coefficients of thermal expansion are used in the PWB to achieve complex functionality, then device versatility is improved, but thermal warpage occurs causing connection disconnection

Engineering Contradiction:

Improveboard functionalityVSAvoidconnection stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent directly addresses thermal expansion by using springs that can accommodate the dimensional changes caused by differential thermal expansion of PCB layers. The springs expand and contract with temperature changes, maintaining reliable electrical contact despite the warpage induced by multi-layer PCB construction with different materials.

Inventive Principle:

Principle #37Thermal expansion

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 flexible connection minimizes breakage and shorting, reduces the need for field repairs, and enhances reliability, particularly in applications like military and space where repair is not feasible, by allowing the springs to adjust with board warpage without compromising the connection.

Implementation Method 1

These materials have different coefficients of thermal expansion. When exposed to the specified temperatures of the system (e.g., −40 degrees Celsius to 140 degrees Celsius), the different layers of the board expand and contract at different rates, thus causing warpage of the board.

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

A semiconductor device package comprise a ball grid array (BGA). The BGA is coupled to a plurality of flexible springs comprising one or more turns and configured to couple to the BGA.

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8531821B2System for securing a semiconductor device to a printed circuit board

Publication Date: 2013.09.10 RAYTHEON CO

AI summary

In accordance with the teaching of the present invention, a system and method for securing a ball grid array to a printed wire board is provided. In a particular embodiment, a ball grid array comprises one or more balls configured to attach to a spring comprising one or more turns. In addition, there is a spacer plate configured to align and separate the springs, a soldering aid configured to align solder on the printed wire board and a printed wire board configured with conductive pads to attach to the ball grid array via the springs.