Semiconductor Device With Mixed Bumps for Warping-Resilient BGA Mounting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The mounting reliability of BGA-type semiconductor devices is compromised due to stress concentration at the bonding interface caused by thermal expansion coefficient differences between the package body and mounting substrate, exacerbated by substrate warping, which affects bonding strength and followability, particularly when the substrate is convex.
Innovation Solution
A semiconductor device design incorporating both core solder bumps with cores and coreless solder bumps without cores, where core solder bumps are positioned at stress-concentrated areas and coreless solder bumps provide better followability to substrate warping, enhancing bonding strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If core solder bumps are used to disperse stress at the bonding interface, then bonding strength is improved, but followability to substrate warping deteriorates
Solution Approach 1:
The patent applies local quality by using different solder bump types (core and coreless) at different locations on the substrate. Core solder bumps are placed at specific positions where stress dispersion is needed, while coreless solder bumps are positioned where better followability to substrate warping is required. This spatial differentiation of properties resolves the contradiction between bonding strength and adaptability to warping.
Solution Approach 2:
The patent employs a composite approach by combining two types of solder bumps (core and coreless) in a single assembly. Each type contributes different properties: core solder bumps provide stress dispersion and bonding strength, while coreless solder bumps provide flexibility and followability to substrate warping. The combination creates a system that achieves both competing objectives simultaneously.
2Stress or pressure
If core solder bumps are used to disperse stress, then stress concentration is reduced, but mounting reliability deteriorates due to poor followability to substrate warping
Solution Approach 1:
The patent addresses this contradiction by locally optimizing the solder bump configuration. Core solder bumps are strategically positioned where stress concentration occurs, while coreless solder bumps are placed in areas requiring followability to substrate warping. This localized differentiation ensures both stress dispersion and mounting reliability are achieved.
Solution Approach 2:
The composite structure of mixed core and coreless solder bumps resolves the contradiction between stress dispersion and mounting reliability. The core solder bumps handle stress concentration through their internal core structure, while the coreless solder bumps maintain mounting reliability by conforming to substrate warping, achieving both objectives in the same system.
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 combination of core and coreless solder bumps improves mounting reliability by reducing stress at the bonding interface and allowing flexible adaptation to substrate warping, maintaining device alignment and image quality.
Implementation Method 1
the presence of the core an disperse the stress added due to the difference in thermal expansion coefficient between the package body and the mounting substrate
Implementation Method 2
the BGA semiconductor device is mounted on the mounting substrate by applying heat treatment (reflow) to melt the solder bump
Data Source
AI summary
To improve the mounting reliability of a semiconductor device. The semiconductor device includes: a package body including a semiconductor chip and having a plurality of electrode pads arranged on one surface; and a plurality of bump electrodes that are individually bonded to the plurality of electrode pads, respectively. The plurality of bump electrodes include core bump electrodes including cores and coreless bump electrodes without cores.