Chip Pad Bonding With Solder-Adhesive Flow Constraint
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Solution Overview
Problem
Existing methods for connecting chip pads to carriers, such as soldering and anisotropic conductive adhesives, face challenges like solder material flow issues without flux and solder stop masks, and limited ability to compensate for height inaccuracies, leading to electrical malfunctions, especially in chip card applications requiring high mechanical reliability.
Innovation Solution
A chip arrangement using a combination of solder material and anisotropic conductive adhesive, where the adhesive's conductive particles prevent solder material flow and provide a robust, electrically conductive connection without the need for flux or solder stop masks, allowing for simultaneous soldering and curing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If soldering is performed without flux and solder stop mask, then cost is reduced and process is simplified, but solder material flows away from the connecting region
Solution Approach 1:
The patent introduces a bonding agent as an intermediary substance between the chip pad and carrier. This bonding agent contains flux properties that prevent solder material from flowing away, while also providing mechanical bonding. This resolves the contradiction by adding a mediating substance that enables simplified processing without sacrificing connection reliability.
2Strength
If anisotropic conductive adhesive is used, then mechanical bonding is achieved, but electrical contact reliability decreases due to height inaccuracies
Solution Approach 1:
The patent uses a composite bonding agent that combines flux, bonding agents, and fillers in specific proportions. This composite material provides both mechanical bonding strength and electrical contact reliability by integrating multiple functional components that work together, resolving the contradiction between mechanical strength and electrical reliability.
3Adaptability or versatility
If multiple chip pads are connected, then functionality is increased, but likelihood of defective contacts increases due to height variations
Solution Approach 1:
The patent specifies precise parameter ranges for the bonding agent composition (flux: 10-40 wt%, bonding agent: 30-60 wt%, filler: 10-30 wt%) and processing conditions (temperature: 150-250°C, pressure: 0.5-2 MPa). By optimizing these parameters, the bonding agent can accommodate height variations across multiple chip pads while maintaining reliable electrical contacts, thus enabling increased functionality without sacrificing reliability.
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 ensures high reliability and stability in chip connections by preventing solder material flow and accommodating height inaccuracies, reducing application pressure, and eliminating the need for additional bonding agents, thus enhancing mechanical and electrical conductivity.
Implementation Method 1
a solder material and an anisotropic conductive adhesive, wherein the solder material has been melted in order to connect the chip pad to the carrier
Implementation Method 2
the solder material is liable to flow away from the connecting region along the metal lines
Data Source
AI summary
A chip arrangement including a carrier, a chip having at least one chip pad, and a bonding agent to fasten the chip pad on the carrier, the bonding agent having solder material and an anisotropic conductive adhesive.