Jet Solder Bath Guide Structure for Stable Lead-Free Wetting
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Solution Overview
Problem
The existing jet soldering apparatuses face challenges with lead-free solder having a higher melting point, causing the molten solder to solidify before reaching the secondary jet nozzle, leading to incomplete wetting and solder bridges, and oxide formation on the waves of molten solder between nozzles, which affects solder quality.
Innovation Solution
A jet solder bath configuration with a guide portion that extends between the primary and secondary jet nozzles, featuring a slit or recessed portions to prevent interference and maintain molten solder flow, ensuring the molten solder from the primary nozzle remains fluid and avoids oxide formation, allowing for effective soldering without bringing the nozzles closer or combining them into a single unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the primary and secondary jet nozzles are separated from each other, then the roughly waved molten solder can enter through-holes and sharp corners, but the molten solder may cool and solidify before reaching the secondary nozzle, causing solder bridges and incomplete wetting
Solution Approach 1:
The patent changes the physical parameters of the molten solder by introducing a heating zone that maintains the solder temperature above its melting point during transit between nozzles. This parameter change (temperature maintenance) prevents solidification while preserving the beneficial wave characteristics for entering through-holes and sharp corners.
Solution Approach 2:
The patent introduces a heating zone as an intermediary element between the primary and secondary jet nozzles. This intermediary maintains the molten state of the solder during transit, preventing solidification without requiring the nozzles to be closer together or combined into a single unit.
2Loss of time
If the primary and secondary jet nozzles are brought closer or combined into a single unit, then the carriage time is reduced, but the wave actions of respective nozzles cancel each other and oxide formation occurs
Solution Approach 1:
The heating zone serves as an intermediary that allows the nozzles to remain separated while eliminating the harmful effect of cooling. This enables both nozzles to maintain their independent wave actions without interference, preventing oxide formation while avoiding the need to reduce nozzle separation.
Solution Approach 2:
The patent converts the potentially harmful long transit time into a benefit by using the heating zone to maintain solder temperature. The extended time between nozzles, which would normally cause solidification, becomes advantageous because the heating zone ensures the solder remains molten, allowing both wave actions to work effectively without cancellation.
3Reliability
If lead-free solder is used instead of Sn-Pb solder, then the melting point increases to 220°C or more, but the molten solder solidifies more easily during transit
Solution Approach 1:
The patent addresses the higher melting point of lead-free solder by implementing a heating zone that maintains the solder temperature above 220°C during transit. This parameter control (temperature maintenance) compensates for the inherently higher solidification risk of lead-free solder while preserving its superior soldering quality and reliability.
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 configuration prevents premature solidification of molten solder and oxide formation, ensuring stable and complete wetting within the substrate's through-holes, thereby maintaining the effectiveness of both primary and secondary solder flows and improving soldering quality, especially for high-heat applications like electrolytic capacitors.
Implementation Method 1
a first jet nozzle (30) for injecting upward molten solder (S) by a first pump
Implementation Method 2
a second jet nozzle (40) for injecting upward the molten solder (S) by a second pump
Implementation Method 3
a heating zone which heats the substrate (5) and the molten solder (S)
Implementation Method 4
the molten solder S sufficiently spreads from the bottom to top within the through-hole H
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided are a jet solder bath and a jet soldering apparatus using the jet solder bath. The jet solder bath contains first and second jet nozzles which inject molten solder by first and second pumps and a bridge member arranged between the first and second jet nozzles. The bridge member includes a guide portion that guides at least one of flows of the molten solder injected from the first jet nozzle and flowing on the downstream side of the first jet nozzle and of the molten solder injected from the second jet nozzle and flowing on an upstream side of the second jet nozzle, and side members which controls the flow of the molten solder, the side members being arranged near opposite ends of the guide portion across a direction that is perpendicular to the carrying direction of the substrate.