Singulation Assembly for Warped Leadframe Sheets
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Solution Overview
Problem
The existing singulation process for molded leadframe sheets is hindered by warped sheets, which fail to form a stable vacuum seal on saw chuck tables, leading to instability and inaccurate cutting during the singulation process.
Innovation Solution
A saw chuck table with a mechanical clamping assembly that applies a clamping force to warped sheets to flatten them against the table surface, enabling the formation of a vacuum seal, ensuring stable support and accurate cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum force is applied to warped molded leadframe sheets, then the sheets should be held securely on the saw chuck table, but warped sheets fail to form a stable vacuum seal leading to instability
Solution Approach 1:
The clamping assembly applies clamping force to the warped leadframe sheet before vacuum force is applied, preliminarily flattening the sheet to enable subsequent vacuum seal formation. This preliminary mechanical action prepares the sheet surface for effective vacuum adhesion.
Solution Approach 2:
The clamping assembly acts as an intermediary device between the warped sheet and the vacuum system. It temporarily applies mechanical force to flatten the sheet, enabling the vacuum system to then maintain the sheet in a stable, flat state during singulation without continuous clamping.
2Reliability
If clamping force is applied to flatten warped sheets, then vacuum seal can be formed, but the device complexity increases
Solution Approach 1:
The clamping assembly is designed to automatically detect warped sheets and apply clamping force only when needed. The system self-regulates by monitoring sheet flatness and activating clamping only for warped sheets, avoiding unnecessary operation for already-flat sheets.
Solution Approach 2:
The clamping force is applied locally only to the specific areas where warping is detected, rather than uniformly across the entire sheet. This localized approach uses minimal clamping force where needed, reducing overall system complexity while maintaining effectiveness.
3Ease of manufacture
If warped sheets are singulated without clamping, then the process is simpler, but cutting accuracy decreases
Solution Approach 1:
The system dynamically adjusts the singulation process based on sheet condition. Flat sheets undergo simple vacuum-based singulation, while warped sheets automatically receive clamping force. This dynamic adaptation maintains process simplicity for most cases while ensuring precision when needed.
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 clamping assembly effectively stabilizes warped leadframe sheets, allowing for a secure vacuum seal and precise singulation, improving the accuracy and reliability of the cutting process.
Implementation Method 1
A vacuum is applied through holes in the saw chuck table top plate. The vacuum securely holds the leadframe sheet to the saw chuck table top plate
Implementation Method 2
A mechanical clamping assembly operatively associated with the saw chuck table is adapted to be selectively engageable with predetermined portions of a warped molded leadframe sheet supported on the flat upper surface of the saw chuck table
Data Source
AI summary
A singulation assembly for molded leadframe sheets includes a saw chuck table having a flat upper surface with a plurality of holes therein. A vacuum source is in fluid communication with the plurality of holes. A mechanical clamping assembly operatively associated with the saw chuck table is adapted to be selectively engageable with predetermined portions of a warped molded leadframe sheet supported on the flat upper surface of the saw chuck table.