Active Resin Composition for Void-Free BGA Underfilling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in surface mounting of BGA parts is the difficulty in removing flux residue, which leads to corrosion and voids in the under-filling resin, especially with large-scale BGA devices, resulting in reduced product quality and yield due to incomplete filling and thermal decomposition issues.
Innovation Solution
An active resin composition comprising epoxy resin, blocked carboxylic acid compounds, and a curing agent that initiates curing at high temperatures, allowing for fluxless mounting and vacuum treatment to prevent voids and corrosion, facilitating reliable bonding and enhanced thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flux is used for surface mounting, then soldering quality is improved, but flux residue causes corrosion and requires additional washing steps
Solution Approach 1:
The invention extracts and eliminates the flux component from the surface mounting process by using an underfill resin with built-in activating agents that perform both bonding and protective functions, thereby removing the source of flux residue and corrosion problems
Solution Approach 2:
The underfill resin is designed to perform multiple functions simultaneously: it acts as a bonding agent, provides corrosion protection through its activating agents, and eliminates the need for separate flux application and washing steps, thereby improving both reliability and productivity
2Productivity
If wash-less flux is used to eliminate washing steps, then productivity is improved, but decomposition gas damages BGA parts
Solution Approach 1:
The invention changes the chemical parameters of the underfill resin by incorporating specific activating agents (carboxylic acid compounds) that prevent decomposition gas generation while maintaining the wash-less process benefits, thereby protecting BGA parts from damage
Solution Approach 2:
The invention converts the potential harmful effect of thermal curing into a beneficial process by using the curing heat to activate the underfill resin's bonding and protective functions without generating decomposition gas that would damage BGA parts
3Reliability
If large-scale BGA parts are mounted, then device performance is enhanced, but flux residue removal becomes difficult causing corrosion
Solution Approach 1:
The invention extracts the flux substance from the process entirely and replaces it with an underfill resin system that provides equivalent or superior functionality without creating removable residue, making the process equally suitable for large-scale BGA parts
Solution Approach 2:
The underfill resin acts as an intermediary material that performs the bonding function traditionally achieved by flux, but with the added benefit of built-in corrosion protection and no residue formation, facilitating easier manufacturing of large-scale devices
4Reliability
If under-filling resin is applied to fill spaces, then bonding is improved, but voids and unfilled portions reduce product quality
Solution Approach 1:
The invention changes the rheological parameters of the underfill resin by adjusting its viscosity and flow characteristics, enabling complete filling of spaces around BGA parts without trapping voids, thereby achieving both strong bonding and manufacturing precision
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 solution eliminates the need for flux removal, ensures bubble-free and void-free curing, enhances device reliability, and maintains high thermal stability, even with large-scale BGA parts, improving production efficiency and product quality.
Implementation Method 1
a curing agent which can initiate curing reaction at 150° C. or higher
Implementation Method 2
a compound having a carboxylic acid group (e.g., rosin)... an activating agent contained in the flux residue
Implementation Method 3
performing a vacuum treatment and/or heating at a temperature lower than the curing reaction-initiating temperature
Implementation Method 4
heating at a temperature lower than the curing reaction-initiating temperature of the applied active resin composition
Data Source
AI summary
A surface mounting method includes applying an active resin composition to at least part of a surface of a printed wiring substrate; mounting a surface mount device on the substrate; performing reflow soldering; applying an under-filling resin into a space of interest; before and/or after applying the under-filling resin, performing a vacuum treatment and/or heating at a temperature lower than the curing reaction-initiating temperature of any of the applied active resin composition and the under-filling resin; and subsequently, thermally curing the resin composition and the under-filling resin. The active resin composition contains an epoxy resin in an amount of 100 parts by weight, a blocked carboxylic acid compound in an amount of 1-50 parts by weight and/or a carboxylic acid compound in an amount of 1-10 parts by weight, and a curing agent which can initiate curing reaction at 150° C. or higher, in an amount of 1-30 parts by weight.