Reinforcing Electrode Pads and Enclosing Members for PCB Warping Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing semiconductor device connection structures, such as those using land grid array (LGA) packages, face issues with warping due to thermal expansion differences between semiconductor packages and printed circuit boards, leading to reduced connection reliability and solder bridges due to uneven solder distribution and lack of barriers around perimeter components.

Innovation Solution

A printed circuit board design featuring reinforcing electrode pads with larger surface areas and cylindrical enclosing members to manage warping and prevent solder bridges, where the enclosing members enclose the solder connection parts at the perimeter to contain the solder paste and reduce spreading during reflow heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If barriers are formed between all adjacent solder connection parts to prevent solder bridges, then solder bridge prevention is improved, but connection reliability in warping regions is reduced

Engineering Contradiction:

Improvesolder bridge preventionVSAvoidconnection reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies different barrier configurations to different regions: full barriers between adjacent solder connection parts in the center region, and no barriers at perimeter portions. This local differentiation allows solder bridge prevention where needed while maintaining connection reliability in warping-prone perimeter regions where the semiconductor package naturally warps away from the printed circuit board.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If barriers are formed between electrode pads, then solder bridge prevention is improved, but solder paste containment at perimeter portions is insufficient

Engineering Contradiction:

Improvesolder bridge preventionVSAvoidsolder paste detachment and splashing

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent segments the solder connection structure into two distinct regions: a center region with barriers between adjacent solder connection parts for solder bridge prevention, and perimeter portions without barriers to allow proper solder paste containment through reinforcement electrode pads. This segmentation allows each region to address its specific problem independently.

Inventive Principle:

Principle #1Segmentation

3Productivity

If LGA semiconductor packages are used for high-density mounting, then mounting density is improved, but solder paste spreading and solder bridges increase

Engineering Contradiction:

Improvemounting densityVSAvoidsolder paste spreading

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies different structural characteristics to different regions: the center region uses barriers between solder connection parts to restrict solder paste spreading, while perimeter portions use reinforcement electrode pads without barriers to contain solder paste through increased adhesion area. This allows high-density LGA mounting while controlling solder paste behavior in each region according to its specific requirements.

Inventive Principle:

Principle #3Local quality

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 design effectively suppresses warping and reduces solder bridges between adjacent components, enhancing connection reliability and allowing for high-density, miniaturized electronic devices with improved functionality.

Implementation Method 1

Warping may develop in semiconductor packages and printed circuit boards during solder heating and melting due to differences in their coefficients of thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a cylindrical enclosing member being configured to enclose an outer perimeter of the second solder connection part

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 3

Solder pastes thus easily spread out into their surroundings when softened by reflow heating

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS9549472B2Printed circuit board, semiconductor device connection structure, and method of manufacturing a printed circuit board

Publication Date: 2017.01.17 CANON KK

AI summary

First electrode pads formed on one semiconductor package surface include a first reinforcing electrode pad having a surface area larger than that of other first electrode pads. Second electrode pads formed on a printed wiring board on which the semiconductor package is mounted include at least one second reinforcing electrode pad. The second reinforcing electrode pad opposes the first reinforcing electrode pad, and has a surface area greater than that of the other second electrode pads. The first and second electrode pads are connected by solder connection parts. A cylindrical enclosing member encloses an outer perimeter of a solder connection part connecting the first and second reinforcing electrode pads. Increases in the amount of warping of semiconductor devices such as the package substrate and the printed wiring board are suppressed, and the development of solder bridges with respect to adjacent solder connecting parts or adjacent components is reduced.