Activated Resinous Composition for Cleaning-Free BGA Mounting
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Solution Overview
Problem
The increasing size of BGA parts and surface irregularities on printed wiring boards hinder effective cleaning and filling with underfill resin, leading to flux residue corrosion, gas generation, and voids, which compromise product quality and reliability.
Innovation Solution
An activated resinous composition comprising epoxy resin, a carboxylic acid compound, a hardening agent with a high initiation temperature, and a solvent is used for surface mounting, eliminating the need for flux cleaning, ensuring no gas bubbles or voids in the hardened layer, and providing high thermal stability to prevent corrosion and gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cleaning-free flux is used to eliminate corrosion risk, then cleaning step can be eliminated and productivity improves, but gas bubbles are generated during heat hardening that destroy the BGA part
Solution Approach 1:
The patent modifies the chemical parameters of the flux by using a carboxylic acid compound with controlled activity and specific molecular weight range (100-500), and adjusts the ratio of activator to resin to achieve optimal balance between cleaning-free operation and gas bubble prevention during hardening
Solution Approach 2:
The invention creates a composite flux system combining carboxylic acid compound activator with specific resin base (rosin or synthetic resin), where the composite formulation achieves both cleaning-free operation and prevention of gas bubble generation during subsequent hardening processes
2Adaptability or versatility
If BGA part size is increased for functional advancement, then more chips can be mounted, but flux residue cannot be completely removed and corrosion reaction occurs
Solution Approach 1:
The patent changes the chemical parameters of the flux system by using carboxylic acid compounds with specific molecular weights (100-500) and controlling the activator concentration, which enables complete removal of flux residue even from large BGA parts while preventing corrosion
3Ease of manufacture
If surface irregularities are present on printed wiring board, then mounting is more complex, but underfill resin cannot fill all holes and corners completely leaving voids
Solution Approach 1:
The patent modifies the rheological parameters of the underfill resin by adjusting viscosity and adding flow-enhancing agents, enabling the resin to completely fill irregular spaces, holes, and corners on the printed wiring board surface without leaving voids
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 solution reduces manufacturing costs, improves productivity, and ensures reliable adhesion by preventing gas bubbles and voids, enhancing the thermal stability and reliability of the product, even with large BGA parts, and facilitates complete filling with underfill resin.
Implementation Method 1
containing, on the basis of an epoxy resin being solid at a room temperature of 100 parts by weight, a carboxylic acid compound of 1 to 10 parts by weight
Implementation Method 2
a hardening agent of 1 to 30 parts by weight, a hardening reaction initiation temperature of the hardening agent being 150° C. or higher
Implementation Method 3
subjecting this to reflow soldering and heat hardening the coated resinous layer
Implementation Method 4
a solvent of 10 to 300 parts by weight
Data Source
AI summary
Activated resinous composition contains, on the basis of epoxy resin being solid at a room temperature of 100 parts by weight, carboxylic acid compound of 1 to 10 parts by weight, hardening agent of 1 to 30 parts by weight, a hardening reaction initiation temperature of said hardening agent being 150° C. or higher, and solvent of 10 to 300 parts by weight.