Circuit Substrate Uniform Solder Bump Formation
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Solution Overview
Problem
Existing flip-chip mounting technologies face challenges in achieving uniform solder bump shapes and heights due to variations in connection pad shapes, leading to difficulties in connecting chip terminals and deteriorating the quality of electronic components.
Innovation Solution
A circuit substrate with a planarized mounting region, where solder bumps of uniform shape are formed by filling solder particles into openings on a resist-covered surface, which are then melted to create consistent bumps, ensuring precise alignment and connection with chip terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solder bumps are formed in accordance with shapes of connection pads or a pattern, then solder bumps can be formed on the circuit substrate, but variation in the shapes of connection pads causes variation in the shapes of solder bumps, resulting in uneven heights
Solution Approach 1:
The patent changes the controlling parameter from connection pad shape to a standardized resist opening shape. By using openings of uniform shape and size in the resist layer, the solder bump dimensions are controlled by the opening parameters rather than the underlying pad geometry, achieving uniform solder bump shapes despite variations in connection pad shapes.
Solution Approach 2:
The resist layer with standardized openings acts as an intermediary between the connection pads and the solder bumps. This intermediate layer masks the shape variations of the connection pads and provides a uniform template for solder bump formation, decoupling the solder bump geometry from the pad geometry.
2Adaptability or versatility
If connection pads of varying shapes are used, then wiring flexibility is improved, but solder bump height uniformity deteriorates
Solution Approach 1:
The patent decouples the wiring pattern flexibility from the solder bump formation control by using a standardized opening shape in the resist layer. The connection pads can have various shapes to accommodate different wiring needs, but the resist openings maintain uniform dimensions, ensuring consistent solder bump heights regardless of pad shape variations.
3Productivity
If solder bumps with uneven heights are formed, then manufacturing process is simplified, but chip terminal connection quality deteriorates
Solution Approach 1:
The standardized resist openings serve as a mediator that enables simple manufacturing processes while ensuring high connection quality. The uniform opening dimensions provide consistent solder bump formation, and the resist layer can be easily applied and removed, maintaining process simplicity while achieving reliable chip terminal connections through uniform solder bump heights.
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 method improves the quality of electronic components by ensuring uniform solder bump shapes and heights, enhancing positional accuracy and reducing defects such as drop-off and short-circuiting, while allowing for precise chip mounting with reduced load on the substrate.
Implementation Method 1
melting the solder particles to form the solder bumps in the openings
Data Source
AI summary
A circuit substrate includes: a mounting region having an exposed surface that is planarized, and in which a predetermined chip is to be mounted; patterns provided in the mounting region, and including respective top faces that form a part of the exposed surface; and solder bumps provided on the respective patterns, and having substantially same shape as one another.