Window Clamp Assembly for Wire Bonding Leadframe Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wire bonding machines face issues with leadframe buckling and vibration during the bonding process, leading to weak or defective wire bonds due to inadequate support and vacuum system inefficiencies, particularly with vertically stacked integrated circuit packages like QFN packages.
Innovation Solution
A window clamp assembly with a frame structure that engages both the peripheral portion of the leadframe strip and the top surfaces of integrated circuit component stacks, using a support plate with vacuum holes to maintain stability and prevent micro-bouncing, and incorporating a method to clamp the leadframe strip firmly to the support plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a traditional window clamp is used to hold the leadframe strip, then the leadframe can be positioned on the support plate, but the leadframe strip buckles and vibrates during wire bonding, leading to defective bonds
Solution Approach 1:
The window clamp is divided into multiple frame members (first frame member, second frame member, third frame member, fourth frame member) that can independently engage different portions of the leadframe strip and component stacks. This segmentation allows each frame member to provide localized support and restraint, preventing buckling and vibration while maintaining overall stability during wire bonding operations.
2Reliability
If the leadframe strip is loosely supported on the plate, then the vacuum system can be simple, but air leaks occur and vacuum force is insufficient to prevent micro-bouncing
Solution Approach 1:
The window clamp assembly merges multiple functions into a single integrated structure: the frame members simultaneously provide mechanical restraint to prevent buckling, create seals against air leaks, and work with the vacuum system to maintain consistent vacuum force. This combination of functions in one assembly reduces the need for separate components and simplifies the overall system while improving reliability.
3Adaptability or versatility
If the clamp engages only the leadframe strip, then the clamp structure can be simple, but vertically stacked IC packages like QFN are not adequately supported
Solution Approach 1:
The window clamp frame members are designed to engage multiple types of objects with a single structure: they can engage the leadframe strip itself and also engage vertically stacked IC packages (such as QFN packages) mounted on the leadframe. This multi-functional design allows the same clamp assembly to accommodate different package types without requiring specialized fixtures, enhancing adaptability while maintaining reasonable structural complexity.
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 effectively stabilizes the leadframe strip, reducing vibrations and air leaks, resulting in improved bond quality and reliability by maintaining a consistent vacuum force and preventing damage to the leadframe and integrated circuit dies.
Implementation Method 1
a support plate adapted to support the leadframe strip... vacuum holes in the support plate adapted to be registered with portions of the leadframe strip... apply a vacuum force to portions of the leadframe strip to prevent buckling
Data Source
AI summary
A wire bonding machine window clamp assembly. The assembly includes a support plate adapted to support a leadframe strip. The assembly also includes a frame structure defining a central clamp opening adapted to expose a portion of the leadframe strip. The frame structure includes at least one elongate frame member having a first surface portion adapted to engage a top surface of the leadframe strip and a second surface portion adapted to engage upper surfaces of integrated circuit (“IC”) component stacks mounted on the leadframe strip.