Buried Metal Portion PCB for Ultrasonic Bonding
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Solution Overview
Problem
Conventional integrated circuit mounted boards face reliability issues due to dispersion of ultrasonic waves and loads during wire bonding or flip-chip connections, particularly when using gold as the connecting medium, leading to improper connections and reduced reliability.
Innovation Solution
The integration of a metal portion protruding from the metal substrate, buried within an insulating member, enhances the rigidity of the under region, allowing for certain electrical coupling of the integrated circuit bare chip with the printed wiring board, even at high temperatures, by facilitating the transmission of ultrasonic waves and loads in the Z-axis direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fluorine resin or liquid crystal polymer is used as insulating material for high frequency signals, then dielectric loss is reduced, but elastic modulus drastically reduces at high temperature from 150°C to 200°C
Solution Approach 1:
The patent uses a composite structure combining fluorine resin (for low dielectric loss) with glass fiber reinforcement (for high temperature rigidity). The glass fiber mesh is embedded within the fluorine resin insulating layers, creating a composite material that maintains both low dielectric loss at operating frequencies and sufficient elastic modulus at bonding temperatures up to 200°C.
2Reliability
If metal portion is buried in under region of insulating member, then rigidity of under region is enhanced and electrical coupling is ensured, but device complexity increases
Solution Approach 1:
The metal portion embedded in the under region of the insulating member serves multiple functions: it provides mechanical reinforcement to enhance rigidity, acts as an electrical ground reference for the electrode part, and facilitates heat dissipation from the bonded connecting medium. This multi-functional design ensures reliable electrical coupling and bonding process stability without requiring separate components for each function.
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 reliable electrical coupling of the integrated circuit bare chip with the printed wiring board, reducing energy loss and improving the reliability of high-frequency signal handling, such as millimeter waves, while maintaining a high wiring density and restricting peeling off of components.
Implementation Method 1
an ultrasonic wave vibration is applied to the connecting medium on the printed wiring board
Implementation Method 2
the printed wiring board is mounted on a heat stage (ceramic or metal) heated at a temperature from 150° C. to 200° C.
Data Source
AI summary
An integrated circuit mounted board includes a printed wiring board and an integrated circuit bare chip mounted on the printed wiring board. The printed wiring board includes a metal base, an insulating member made of an insulating material and disposed on the metal base, and a wiring pattern disposed on the insulating member. The wiring pattern includes an electrode part to which the integrated circuit bare chip is electrically coupled. The insulating member includes an under region being opposite to the electrode part. The metal base includes a metal substrate and a metal portion protruding from the metal substrate. The metal portion is buried in the under region of the insulating member.