Circuit Board Conductive Layers for Wire Bonding Reliability
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Solution Overview
Problem
In the manufacturing of high-density semiconductor packages, the increased thickness of nickel plating layers on bond fingers makes it difficult to maintain a gap between bond fingers, leading to reduced bonding reliability and increased manufacturing costs due to the need for additional connection terminals and the use of expensive gold in wire bonding processes.
Innovation Solution
A circuit board design featuring conductive layers with different thicknesses and materials, where the upper conductive layer is only on the surface of the lower conductive layer, minimizing gold usage and allowing for wire bonding without auxiliary tools, thereby preventing short circuits and improving bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of nickel plating layer is increased to secure wire bonding environment, then bonding reliability is improved, but gap between bond fingers cannot be maintained and manufacturing cost increases
Solution Approach 1:
The patent applies different thicknesses of conductive layers at different locations. The first conductive layer has a first thickness and the second conductive layer has a second thickness different from the first thickness. This local differentiation allows the bond finger to maintain adequate gap spacing while still providing sufficient thickness for reliable wire bonding at the bonding location.
Solution Approach 2:
The patent changes the thickness parameter of the conductive layers to optimize both bonding reliability and manufacturability. By setting specific thickness values for the first and second conductive layers, the patent achieves adequate gap maintenance while ensuring sufficient bonding area, thereby reducing manufacturing cost and improving ease of manufacture.
2Reliability
If the thickness of nickel plating layer is increased, then bonding reliability is improved, but gap between bond fingers is reduced leading to short circuit risk
Solution Approach 1:
The patent uses conductive layers with different thicknesses where the first conductive layer has a first thickness and the second conductive layer has a second thickness. This local quality differentiation ensures that the bond finger maintains adequate gap spacing to prevent short circuits while still providing sufficient thickness for reliable wire bonding operations.
3Reliability
If thicker nickel plating layer is used, then wire bonding environment is secured, but edge of bond finger becomes rounded reducing bonded area
Solution Approach 1:
The patent optimizes the thickness parameters of the conductive layers to prevent edge rounding. By setting appropriate thickness values for the first and second conductive layers, the patent maintains sharp edges on the bond finger while ensuring sufficient bonding area, thereby improving the shape quality and bonding reliability simultaneously.
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
The solution enables secure wire bonding without short circuits, reduces manufacturing costs by minimizing gold usage, and enhances bonding reliability by increasing the bonding area with a flat upper conductive layer surface.
Implementation Method 1
a lower conductive layer disposed on a corresponding one of the first and second connection pads
Implementation Method 2
an upper conductive layer disposed on an upper surface of the lower conductive layer
Data Source
AI summary
A circuit board includes: an insulating layer, a solder resist layer disposed on the insulating layer and having first and second openings; first and second connection pads respectively disposed within the first and second openings on the insulating layer; and first and second conductive layers respectively disposed on the first and second connection pads, and configured to protrude more than an upper surface of the solder resist layer and to have different thicknesses. Each of the first and second conductive layers includes a lower conductive layer disposed on a corresponding one of the first and second connection pads and an upper conductive layer disposed on an upper surface of the lower conductive layer.