Flip Chip Wiring Board Zig-Zag Grooves Underfill Resin Flow
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Solution Overview
Problem
Conventional flip chip connection methods in semiconductor devices often result in air bubbles forming in the underfill resin between the wiring board and the semiconductor chip due to differences in the spreading speed of the resin on metal and glass epoxy resin surfaces, leading to disturbances and trapped air.
Innovation Solution
The semiconductor device features a wiring board with elongated grooves and zig-zag edges in its openings, where the underfill resin flows along the metal wires for a longer distance than on the glass epoxy resin board core, minimizing the distance difference and reducing the likelihood of air bubbles by ensuring a more uniform resin flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill resin is applied on the wiring board before flip chip connection, then the interstice between wiring board and semiconductor chip is filled with underfill resin, but air bubbles are trapped in the underfill resin due to different spreading speeds on metal and glass epoxy resin surfaces
Solution Approach 1:
The wiring board surface is segmented into different regions (metal wire regions and glass epoxy resin regions) with distinct opening patterns. Elongated openings are formed only over the metal wire regions, while the glass epoxy resin regions remain covered or have different opening configurations. This segmentation allows the underfill resin to spread uniformly across different surface materials without speed differential, preventing air bubble formation while maintaining humidity resistance.
2Volume of moving object
If conventional flip chip connection is used to reduce device size and thickness, then compact semiconductor device is achieved, but air bubbles form in the underfill resin during the connection process
Solution Approach 1:
Different opening patterns are applied to different regions of the wiring board based on the underlying material properties. Over metal wire regions, elongated openings are formed to facilitate uniform resin spreading. Over glass epoxy resin regions, openings are minimized or configured differently. This local quality approach ensures that the underfill resin spreads uniformly across the entire surface during flip chip connection, eliminating air bubbles while maintaining the compact device structure.
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 configuration effectively prevents air bubbles from forming in the underfill resin layer during the curing process, enhancing the reliability and performance of the semiconductor device by ensuring a bubble-free resin fill.
Implementation Method 1
filling an interstice between a wiring board and a semiconductor chip with an insulating resin (underfill resin)
Data Source
AI summary
A semiconductor device has at least a square wiring board having a board core made of an insulating material, wires made of a metal and formed on a first surface of the board core, a solder resist film formed on the first surface to cover the wires, and openings formed by partially opening the solder resist film, wherein a plurality of the elongated wires are arranged in parallel on the bottom of the openings, a semiconductor chip having electrodes flip chip connected to the wires are arranged on the bottom of the openings of the wiring board through a conductive bonding material, and an insulating resin is provided for filling an interstice between the wiring board and the semiconductor chip, wherein the wires extend along a width direction orthogonal to a longitudinal direction of the openings, the openings comprise elongated grooves which extend along at least two opposing sides of the square of the wiring board, a pair of opposing edges of the opening along the longitudinal direction define zig-zag edges in which the widths of the opening seem to be longer and shorter in a repeating sequence, and recessed edge portions which recess toward the outside of the opening formed by the zig-zag edges in the width direction correspond to the wires, and protruded edge portions which protrude toward the inside of the opening formed by the zig-zag edges in the width direction correspond to the board core between adjoining the wires.