Chip Component Mounting with Grooved Solder Deposits
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Solution Overview
Problem
Conventional pre-soldering methods for mounting chip components on circuit boards face issues with displacement due to excessive flux thickness, leading to potential lifting of components during reflow furnace treatment, and solvent bumping causing the Manhattan phenomenon.
Innovation Solution
The method involves flattening solder deposits on circuit boards, forming grooves on these deposits to retain flux, and applying a reduced amount of flux, which is then interposed between the solder deposit and the chip component, allowing for stable evaporation of solvents and preventing component displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flux is applied thick enough to spread over the entire surface of the solder deposit, then the oxidation prevention function is improved, but the chip component displacement occurs due to excessive flux thickness
Solution Approach 1:
The solder deposit surface is segmented into multiple regions by forming grooves that divide the surface into plurality of regions. This segmentation allows flux to be distributed across multiple smaller areas rather than forming a single thick layer, enabling adequate flux coverage for oxidation prevention while maintaining thin overall flux thickness to prevent chip component displacement during reflow processing
Solution Approach 2:
Different regions of the solder deposit are given different local qualities through the groove structure. The grooves create areas with varying flux retention characteristics, allowing the flux to be held in specific locations where it is needed for oxidation prevention, while maintaining thin flux layers in other areas to prevent component displacement
2Manufacturing precision
If the flux coating amount is reduced to prevent displacement, then the chip component position accuracy is improved, but the oxidation prevention function deteriorates
Solution Approach 1:
The grooves are formed on the solder deposit before flux application as a preliminary action. These pre-formed grooves are specifically designed to retain flux during subsequent processing, ensuring that even when flux is applied in thin amounts, it will be held in the groove regions where it is needed to prevent oxidation during reflow processing
Solution Approach 2:
The grooves act as an intermediary structure between the solder deposit and the flux. They provide a mechanical means to retain and distribute the flux, ensuring adequate flux presence for oxidation prevention even when the overall flux coating amount is reduced to thin levels that prevent chip component displacement
3Speed
If the solvent in the flux evaporates rapidly during heat treatment, then the process speed is improved, but the Manhattan phenomenon occurs due to solvent bumping
Solution Approach 1:
The grooves segment the flux layer into multiple smaller regions, which facilitates more uniform and controlled solvent evaporation. This segmentation prevents rapid, uncontrolled bumping that causes the Manhattan phenomenon, while still allowing efficient evaporation to proceed at appropriate rates during reflow processing
Solution Approach 2:
The grooves serve as an intermediary structure that mediates the evaporation process. They provide channels and surfaces that facilitate controlled solvent release, preventing the sudden pressure buildup that causes bumping and the Manhattan phenomenon, while maintaining efficient evaporation rates for process speed
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 effectively reduces flux thickness between the solder deposit and chip components, preventing displacement and solvent-induced issues during heat treatment, while maintaining flux's oxidation prevention capabilities, thereby ensuring stable and reliable chip component mounting.
Implementation Method 1
The flux plays an important role in preventing oxidation of the solder associated with melting
Implementation Method 2
the solvent contained in the flux can be stably and uniformly evaporated during the heat treatment
Implementation Method 3
The solder deposit is then melted by passing the circuit board through a reflow furnace without chip components on the solder paste
Data Source
AI summary
A method for mounting a chip component includes the steps of: flattening a solder deposit adhering onto a land terminal of a circuit board; forming grooves on the solder deposit simultaneously with or after flattening the solder deposit; coating the solder deposit with a flux; and placing a chip component on the solder deposit with the flux interposed therebetween.