Grooved Lead Finger for Wire Bond Anchoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wire bonding techniques often result in unreliable second bonds between bond wires and lead frames, leading to issues such as broken stitch bonds and heel cracks, which compromise the reliability of semiconductor devices.
Innovation Solution
The formation of channels on the substrate electrical connection pads of the lead frame, where bond wires are embedded to increase the contact surface area and provide an anchor-locking mechanism, enhancing the strength and reliability of the second bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wire bonding techniques are used to form stitch bonds between bond wires and lead fingers, then the bonding process is simple and fast, but the bond reliability is poor resulting in broken bonds and heel cracks
Solution Approach 1:
The lead finger surface is segmented into multiple grooves that divide the bonding area into distinct sections. This segmentation allows the bond wire to be embedded within the grooves, creating multiple anchoring points along the wire length rather than a single surface bond, thereby improving reliability without requiring complex external structures
Solution Approach 2:
The invention transitions from a two-dimensional surface bond to a three-dimensional embedded bond by creating grooves that extend into the lead finger substrate. This dimensional change allows the bond wire to be partially embedded within the grooves, increasing contact area and providing mechanical anchoring that prevents bond failure under stress
2Strength
If the bond wire is pressed onto the surface of the lead finger using ultrasonic and thermal energy, then the bonding process is efficient, but the bond strength is insufficient to withstand mounting and usage stresses
Solution Approach 1:
The grooves are pre-formed in the lead finger before the wire bonding process. This preliminary action creates ready-made embedding channels that guide and secure the bond wire during the bonding process, ensuring consistent embedding depth and orientation without requiring complex real-time control during bonding
Solution Approach 2:
The invention replaces part of the mechanical bonding mechanism (ultrasonic pressure and heat) with a geometric locking mechanism. The grooves provide passive mechanical anchoring through their geometry alone, reducing dependence on high ultrasonic energy and thermal input while achieving stronger, more reliable bonds
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 results in a more reliable and robust second bond, improving the overall reliability of semiconductor devices by increasing the bond contact surface area and providing a locking mechanism that withstands stresses during mounting and usage.
Implementation Method 1
A stitch bond of a wire is formed on the substrate such that a first end of the wire is embedded within the plurality of channels of the substrate
Data Source
AI summary
A lead finger of a lead frame has a number of channels or grooves in a portion of its top surface that provide a locking mechanism for securing a bond wire to the lead finger. The bond wire may be attached to the lead finger by stitch bonding.