Electrode Pad Width Variation for Wire Bonding
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Solution Overview
Problem
In thermal flow rate measuring devices, the lack of clear definition in the bonding region for wires on electrode pads makes it difficult to determine the correct bonding position, leading to potential interference with other components.
Innovation Solution
The electrode pads on sensor chips are modified with a straight portion and a changed-width portion, specifically a wide, narrow, or boundary portion at the leading end, which serves as a distinct wire-bonding-allowed region, clearly defining where the wire should be bonded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an electrode pad extends linearly with a uniform width from the measuring section, then the structure is simple and easy to manufacture, but it is difficult to identify the wire-bonding position and determine correct bonding location
Solution Approach 1:
The patent applies a width change in the electrode pad structure (analogous to visual differentiation) where the electrode pad includes a first portion with width W1 and a second portion with width W2, creating a distinguishable region that clearly indicates the wire-bonding position. This structural 'color change' through width variation solves the identification problem while maintaining manufacturing simplicity.
2Device complexity
If an electrode pad has a uniform shape, then the manufacturing process is simple, but it is difficult to determine whether a wire is bonded to the correct position during inspection
Solution Approach 1:
The width variation in the electrode pad creates a visually distinguishable bonding region that enables easy inspection of wire bonding positions. The first portion (width W1) and second portion (width W2) form a clear geometric marker that simplifies quality control while maintaining overall device simplicity.
3Device complexity
If the wire-bonding position is not clearly defined, then the electrode pad structure remains simple, but the wire may interfere with other components of the device
Solution Approach 1:
The patent applies local quality by creating a specific region (the second portion with width W2) that has different dimensional properties from the rest of the electrode pad. This localized width change clearly defines the wire-bonding area, ensuring proper wire placement and preventing interference with other device components while maintaining simplicity elsewhere in the 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 clear definition of the bonding position prevents interference between wires and other components, facilitating efficient wire bonding and avoiding errors in the manufacturing process.
Implementation Method 1
the measurement is based on the principle that heat removed from a heater by a fluid changes depending on the flow rate of the fluid
Data Source
AI summary
A measuring device includes two sensor chips that measure a flow rate of a fluid flowing through a pipe, electrode pads extending from a temperature measuring section and from a heater, respectively, toward peripheries of the two sensor chips, and wires that are electrically connected to the electrode pads and via which a measurement signal that is output from the temperature measuring section or the heater is transmitted to outside of the sensor chips. Each of the electrode pads includes a straight portion that extends linearly from the temperature measuring section or the heater and a wide portion that is formed at a leading end of each of the electrode pads and is wider than the straight portion, and an entire surface area of the wide portion is set as a wire-bonding-allowed region, to which one of the wires is to be bonded.