Localized Material Transfer for Chip Metallization on Irregular Surfaces
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Solution Overview
Problem
Existing methods for forming fusible-ball type metallizations on electronic chips, such as screen-printing, are costly and unsuitable for individual chips or irregular surfaces, and face challenges with recesses, making it difficult to secure electronic chips by flip-chip bonding.
Innovation Solution
A method for localized deposition of material involves depositing a material on a support, positioning an element against it, and applying heat and/or chemical treatment to increase adhesion, ensuring the material remains secured to the element after separation from the support, using materials with specific contact angles to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If screen-printing is used to form fusible balls on multiple chips simultaneously, then manufacturing cost is reduced, but it becomes unsuitable for individual chips and increases complexity for localized deposition
Solution Approach 1:
The patent divides the deposition process into two independent stages: first depositing material on a support structure, then transferring to the target chip. This segmentation allows the same process to serve both batch processing (multiple chips on one support) and individual chip applications, resolving the contradiction between productivity and adaptability
Solution Approach 2:
The support structure acts as an intermediary between the deposition source and the target chip. Material is first deposited on the support, then transferred to the chip through contact and heat treatment. This intermediary enables flexible application to both individual chips and multiple chips simultaneously, while simplifying the deposition process compared to direct screen-printing on chips
2Manufacturing precision
If screen-printing is applied directly on individual electronic chips, then localized deposition is achieved, but manufacturing cost significantly increases
Solution Approach 1:
The support structure serves as a cost-effective intermediary that simplifies the manufacturing process. Instead of requiring expensive precision screen-printing equipment for each individual chip, the material is deposited on a simple support structure using less precise methods, then transferred to the chip. This maintains localized deposition accuracy while significantly reducing manufacturing cost
Solution Approach 2:
The material is preliminarily deposited on the support structure before being transferred to the chip. This preliminary action allows using simpler, less expensive deposition techniques on the support, while the precise localization is achieved during the transfer step when the chip contacts the support. This resolves the contradiction between manufacturing precision and ease of manufacture
3Manufacturing precision
If screen-printing is used on surfaces with recesses, then complete coverage is difficult to achieve, but alternative methods increase device complexity
Solution Approach 1:
The support structure acts as an intermediary that simplifies deposition on complex surfaces. Material is deposited on the flat support surface, then transferred to the chip by contact. This two-step process achieves complete coverage of recesses without requiring complex deposition equipment, as the material simply flows into recesses during the contact phase
Solution Approach 2:
Instead of directly depositing material onto the chip surface with recesses (which is difficult), the patent inverts the approach: material is first deposited on a flat support, then the chip is pressed against the support to transfer material into the recesses. This inversion simplifies the deposition step while ensuring complete coverage of complex surfaces
4Ease of manufacture
If screen-printing screen is pressed against irregular surfaces, then material deposition is enabled, but flatness problems occur
Solution Approach 1:
The support structure serves as an intermediary with a flat surface for material deposition. The irregular chip surface contacts the flat support during transfer, allowing material to be deposited on the flat support without flatness problems, then transferred to the irregular chip surface. This resolves the contradiction between ease of manufacture and manufacturing precision
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
Enables localized deposition on small, individual electronic chips and irregular surfaces with recesses, reducing costs and ensuring secure bonding without direct screen-printing, applicable to various applications including metallizations, sealing beads, and functionalization layers.
Implementation Method 1
heat and/or chemical treatment of the material portion increasing, at the end of the heat and/or chemical treatment, the adhesion force of the material against the portion of the element
Implementation Method 2
annealing is implemented at a temperature higher than or equal to the melting temperature of the fusible material so that the portions 15 switch into the liquid state then form, upon completion of this annealing and after return of the fusible material into the solid state, balls 16
Implementation Method 3
heat and/or chemical treatment of the material portion increasing, at the end of the heat and/or chemical treatment, the adhesion force of the material against the portion of the element
Data Source
AI summary
A method is provided for localised deposition of a material over an element, including deposition of a portion of the material over a portion of a surface of a support; positioning of a portion of the element against the portion of the material; annealing of the material portion increasing, at the end of the treatment, the adhesion force of the material against the portion of the element, the materials of the portion of the element and of the portion of the surface of the support being selected such that the adhesion of the material against the portion of the element is, at the end of the annealing, higher than that of the material against the portion of the surface of the support; and separation of the element and the support at the interface between the material and the portion of the surface of the support, the material remaining secured to the portion of the element.