Wiring Board Concave Insulating Layer Resin Flow
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Solution Overview
Problem
Conventional wiring boards for flip-chip mounting of semiconductor chips face challenges in preventing void formation and resin overflow, leading to reduced bonding strength and potential damage to surrounding circuit elements due to variations in underfill resin fluidity and the need for additional processing steps to form dam structures.
Innovation Solution
A method of manufacturing a wiring board with a concave portion in the insulating layer larger than the semiconductor component, allowing increased fluidity of underfill resin and preventing resin overflow, while eliminating the need for additional processing steps by forming a step-like shape that exposes pads flush with the insulating layer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill resin with high fluidity is used to avoid void formation, then void formation is reduced, but resin overflow to surrounding areas increases
Solution Approach 1:
The patent applies local quality by creating a dam structure at specific locations (around the chip mounting area) to control resin flow locally. The dam structure is formed by raising the insulating layer height in peripheral areas, creating a localized barrier that restricts resin overflow to specific regions while allowing adequate resin flow for filling the gap between chip and board.
Solution Approach 2:
The dam structure is formed in advance during the manufacturing process, before the underfill resin application. The insulating layer is patterned to create elevated peripheral areas that will serve as barriers, preparing the structure beforehand to control resin flow behavior when high-fluidity resin is applied.
2Object-generated harmful factors
If a dam structure is added to prevent resin overflow, then resin overflow is restricted, but manufacturing complexity increases
Solution Approach 1:
The patent merges the dam structure function with the existing insulating layer. Instead of adding a separate dam component or structure, the insulating layer itself is patterned to create both its protective function and the dam structure function, combining multiple functions into a single integrated layer.
Solution Approach 2:
The insulating layer serves multiple functions: electrical insulation, mechanical support, and resin flow restriction through its elevated peripheral areas. This multi-functional design eliminates the need for separate dam structures, reducing manufacturing complexity while maintaining the overflow prevention function.
3Reliability
If the board surface is flattened to prevent void formation, then void formation is reduced, but additional processing steps are required
Solution Approach 1:
The board surface is flattened in advance during the insulating layer formation process, before chip mounting and resin application. The insulating layer is deposited and patterned to create a flat mounting surface, preparing the structure beforehand to ensure proper resin flow and eliminate void formation without requiring additional processing steps later.
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 approach enhances bonding strength between the chip and the board, reduces void formation, and limits resin overflow, thereby improving connection reliability and preventing damage to adjacent circuit elements without increasing manufacturing complexity or costs.
Implementation Method 1
The underfill resin is infiltrated into a small gap (approximately 50 μm under current technology) between the chip and the board by capillary action.
Data Source
AI summary
A method of manufacturing a wiring board for use in mounting of an electronic component includes: forming an outermost wiring layer on a surface side where the electronic component is mounted; forming an insulating layer so as to cover the wiring layer; and forming a concave portion in the insulating layer. The concave portion is formed by removing, using a mask formed in a required shape by patterning, an exposed portion of the insulating layer in a step-like shape until a surface of a pad defined at a portion of the wiring layer is exposed. The concave portion is preferably formed by removing the portion of the insulating layer by sand blast.