Micro-ball Loading Device with Segmented Magnetic Mask Attachment
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Solution Overview
Problem
The existing methods for loading micro-balls onto semiconductor devices using a transfer mask suffer from positional deviations and poor precision due to magnetic force-induced bending of the transfer mask, leading to defects and increased manufacturing costs in BGA and CSP packages.
Innovation Solution
A loading device with a mask attachment mechanism that uses different magnetic forces at the central and peripheral edges to prevent mask warping, combined with a vibrating mechanism to ensure accurate placement of micro-balls onto terminal regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transfer mask is fixed using magnetic force to load micro-balls onto substrate, then the loading process is simplified and productivity is improved, but the magnetic force causes the transfer mask to bend and deviate from the substrate, deteriorating manufacturing precision
Solution Approach 1:
The magnetic field is segmented into multiple independent magnets arranged in an array, allowing selective application of magnetic force to different regions of the transfer mask. This enables the mask to be held firmly at edges while maintaining flatness across the loading area, resolving the contradiction between strong magnetic attachment and positioning precision.
Solution Approach 2:
Different regions of the transfer mask are subjected to different magnetic forces: strong magnetic force is applied at the edges for secure attachment, while weak or no magnetic force is applied at the center to prevent bending. This local differentiation of magnetic force quality allows the mask to remain both firmly attached and precisely positioned during micro-ball loading.
2Reliability
If strong magnetic force is applied to hold the transfer mask firmly on the substrate, then the mask attachment reliability is improved, but the mask bends more causing micro-balls to stick to through-hole side surfaces, worsening manufacturing precision
Solution Approach 1:
The magnetic field is divided into multiple independent magnets positioned at specific locations. By placing magnets primarily at the edges and corners of the transfer mask rather than uniformly across the entire area, the mask achieves firm attachment through distributed magnetic forces while avoiding concentrated bending that would cause micro-balls to adhere to through-hole sides.
Solution Approach 2:
The magnetic force distribution is optimized locally: strong magnetic force is concentrated at the periphery of the transfer mask for secure attachment, while the central region experiences minimal magnetic force to maintain flatness and prevent micro-ball adhesion to through-hole surfaces, thus simultaneously achieving reliability and precision.
3Duration of action of moving object
If the transfer mask is bent during substrate release, then the magnetic force release is delayed at the central portion, but this causes through-hole position deviation in the vertical direction, worsening manufacturing precision
Solution Approach 1:
By segmenting the magnetic field into multiple discrete magnets, the release process occurs progressively across different regions rather than simultaneously. The segmented magnetic forces allow the mask to release from the substrate in a controlled sequence, preventing the bending and vertical position deviation that occurs with uniform magnetic fields during release.
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 prevents positional deviations of micro-balls and enhances the yield and reduces manufacturing costs by ensuring precise loading of micro-balls onto semiconductor devices.
Implementation Method 1
Magnet (22) is arranged on the lower side of backing plate (20), and transfer mask (10) containing the metal mask is held onto backing plate (20) by the magnetic force of magnet (22)
Implementation Method 2
a vibrating device that applies vibration to the transfer mask
Data Source
AI summary
A device for loading electro-conductive ball onto the terminal regions of a substrate more correctly and reliably is disclosed. Micro-ball loading device (200) may have the following parts: backing plate (220) supporting substrate (100) such that plural terminal regions (108) formed on one surface of substrate (100) are free, transfer mask (210), which contains a metal mask and has plural through-holes (216) formed corresponding to plural terminal regions (108) of the substrate, fixing block (230) onto which end portions (210a) of the transfer mask are fixed such that transfer mask (210) faces one surface of the substrate, and magnet part (240), which attaches transfer mask (210) by magnetic force to the side of backing plate (220); for magnet part (240), the attachment force to the center portion of the substrate is less than that of the peripheral edge portion.