C4NP Solder Fill Head Seal Design for Consistent Cavity Fill
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Solution Overview
Problem
Current fill heads used in the C4NP process for placing solder bumps on molds suffer from excessive seal wear and premature seal failure due to rigid seals and 'round' O-ring seals prone to rolling, leading to inconsistent seal contact force and width, resulting in poor cavity fill and solder leaks.
Innovation Solution
A seal configuration with a support groove in the fill head that securely holds the seal, preventing rotational movement and featuring a contact surface to maintain consistent seal contact force and width, ensuring proper cavity fill with minimal wear, using a seal support groove with angled or parallel side walls and a resilient member for improved compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rigid seals are used in the fill head, then the seal structure is simple and easy to manufacture, but the seal contact force and width vary due to height variations, leading to excessive seal wear and poor cavity fill
Solution Approach 1:
The patent replaces rigid seals with compliant seals that can dynamically adapt to height variations between the fill head and mold plate. The compliant seal deforms elastically to maintain consistent contact force and width across varying gaps, resolving the contradiction by introducing dynamic adaptability while maintaining manufacturing simplicity through elastic material properties rather than complex mechanisms.
Solution Approach 2:
The patent changes the physical parameter of the seal from rigid to compliant by selecting materials with appropriate elastic modulus. This parameter change allows the seal to deform and accommodate height variations, maintaining consistent seal contact force and width without requiring complex adjustment mechanisms, thus improving reliability while keeping the structure simple.
2Ease of manufacture
If round O-ring seals are used in the fill head, then the seal installation is simple, but the seal is prone to rolling in the support groove, leading to premature seal failure
Solution Approach 1:
The patent replaces symmetric round O-ring seals with asymmetric rectangular or square cross-section seals. The asymmetric geometry prevents rolling motion in the support groove because the seal cannot rotate without lifting off the support surface. This maintains simple installation while dramatically improving reliability by eliminating the rolling failure mode.
Solution Approach 2:
The patent inverts the conventional approach by using sharp corners (absence of curvature) rather than rounded edges. The rectangular cross-section with sharp corners creates stable contact points on the support groove surfaces, preventing the seal from rolling or rotating during operation, thus extending seal service life while keeping installation simple.
3Ease of manufacture
If the fill head moves across the mold plate with mechanical tolerances, then the system has practical manufacturability, but the distance variation causes seal contact force and width variation, leading to solder leaks
Solution Approach 1:
The patent uses a flexible compliant seal that can deform to accommodate distance variations caused by mechanical tolerances. The seal acts as a flexible element that maintains consistent contact force and width despite gaps varying within the tolerance range, resolving the contradiction by allowing practical manufacturability while ensuring manufacturing precision through material compliance.
Solution Approach 2:
The patent introduces a compliant seal that inherently cushions against the effects of height variations before they can cause problems. The elastic deformation of the seal absorbs the variability in gap distance, providing a buffer that maintains consistent seal contact parameters despite mechanical tolerance variations in the fill head positioning system.
Data Source
AI summary
A seal, fill head, and system are provided. The seal is adapted to cooperate with a fill head that is configured to place conductive bonding material into cavities on a mold. The seal comprises a first outer wall that is configured to abut a first adjacent wall of a support groove in a fill head. A second outer wall is configured to abut a second adjacent wall of a support groove in a fill head. An outer horizontal wall is situated between the first outer wall and the second outer wall. The outer horizontal wall comprises at least a first portion that is configured to abut an upper portion of the support groove. A convex bottom portion extends from the first and second outer walls. The convex bottom portion is configured to cooperate with a top surface of a mold.