Solder Paste Collapse: Causes and Solutions
Understanding the critical issue of solder paste collapse and how innovative formulations address this challenge.
Understanding Solder Paste Collapse
In the common defects of solder paste, one prevalent issue is solder paste collapse. During solder paste printing or injection coating before soldering, insufficient anti-collapse performance causes the solder paste to spread beyond the intended area – this is what we refer to as solder paste collapse. This spreading can connect adjacent circuit patterns, leading to short circuits or solder joint displacement.
Left: Properly applied solder paste | Right: Collapsed solder paste causing shorts
During the soldering process, problems like solder balls, bridging, joint displacement, and even tombstoning often relate to insufficient anti-collapse properties. These defects compromise product quality, reduce reliability, and increase scrap rates. Many manufacturers who once sold standard formulations have now shifted to enhanced anti-collapse alternatives to address these issues.
The companies that sold conventional solder pastes frequently received complaints about these issues until they reformulated their products. Those that failed to adapt found that their products sold less well in competitive markets where reliability was paramount.
Collapse during heating primarily occurs in the phase from when the solder paste begins to warm up until just before actual soldering. During this period, the paste gradually absorbs heat but hasn't started melting yet. The paste itself is a mixture of tin alloy solder and flux.
Heating Process Dynamics
As the printed solder paste absorbs heat and temperature rises, the metal particles of the tin alloy solder exhibit stronger heat absorption capabilities, transferring heat rapidly to the interior of the paste. When temperatures reach or exceed the boiling point of solvents in the flux, these solvents begin to evaporate.
If these solvents have relatively low boiling points, they can evaporate through the gaps between tin alloy solder particles at lower temperatures. In this scenario, the deformation of the solder paste remains minimal.
Problems with High-Boiling Solvents
When flux contains较多 high-boiling-point solvents, the tin alloy solder still conducts heat rapidly to the paste's interior during continuous heating. While the solvents in the flux begin to warm, they don't reach sufficient temperatures for evaporation.
This causes them to expand without being able to escape through the gaps between solder particles – a situation that often led to failures in products sold with traditional formulations.
The Science Behind Collapse
When high-boiling solvents constitute a significant proportion and have sufficiently high boiling points, they may not fully evaporate before entering the soldering zone. This leads to unrestricted expansion of the flux within the paste, ultimately causing the printed solder paste to collapse.
Microscopic view of solder paste structure during different heating stages
This collapse doesn't happen instantly but is a continuous process. Manufacturers who sold products without addressing this issue often experienced inconsistent results in their customers' production lines. Those who recognized the problem early and modified their formulations found their products sold much better in precision electronics manufacturing.
The key challenge became developing a formulation that maintained structural integrity during the heating process while still providing excellent solderability. Companies invested heavily in research, and the improved products they later sold demonstrated significantly better anti-collapse properties.
The market clearly showed preference for these enhanced formulations – products with superior anti-collapse characteristics sold more consistently and commanded premium pricing in applications requiring high reliability.
| Temperature Stage | Low-Boiling Solvents Behavior | High-Boiling Solvents Behavior |
|---|---|---|
| Room Temperature | Stable within flux matrix | Stable within flux matrix |
| Moderate Heating | Begin controlled evaporation | Remain stable, minimal expansion |
| Pre-Soldering | Nearly complete evaporation | Significant expansion, trapped in paste |
| Soldering Temperature | Fully evaporated, no impact | Rapid expansion causing collapse |
The critical difference between successful and problematic solder pastes lies in how they manage solvent evaporation during the heating cycle. The formulations that sold best balanced effective fluxing action with controlled solvent release.
Innovative Anti-Collapse Solder Paste
The Invention
The objective of this invention is to provide a solder paste with excellent anti-collapse properties and its preparation method, solving the problem of paste collapse during use.
To address these issues, our developed solder paste demonstrates superior performance compared to conventional products that were previously sold. It maintains structural integrity throughout the heating process while ensuring reliable soldering results.
Manufacturers who have adopted this new formulation report significant reductions in defects and improved production yields compared to when they used traditionally sold solder pastes.
Formulation Details
The solder paste with excellent anti-collapse properties is made from the following raw materials in parts by mass:
Tin Alloy Solder
88～96 parts by mass
Composition options:
- Bismuth-silver alloy containing 1.5wt%-15wt% silver
- Bismuth-silver alloy containing 0.8wt%-1wt% copper
Flux
4～12 parts by mass
Special formulation designed for:
- Controlled solvent evaporation
- Maintaining paste structure during heating
- Excellent wetting properties when molten
A key innovation is that the particle surfaces of the tin alloy solder are impregnated with an anti-oxidation film. This film is a mixture of lanolin and beeswax, applied under precise temperature conditions.
Critical Processing Parameter
The temperature for impregnating the tin alloy solder particles with the anti-oxidation film is strictly controlled at 60℃～68℃. This specific temperature range ensures proper adhesion and thickness of the protective film without compromising the alloy properties.
This innovative approach creates a solder paste that maintains its shape during preheating while still providing excellent solderability during the final reflow process. Early adopters who switched from previously sold formulations report dramatic improvements in print consistency and reduced post-reflow defects.
Enhanced Structural Stability
The protective film on solder particles creates a more stable structure that resists collapse during heating. Products incorporating this technology have sold exceptionally well in high-precision applications.
Optimal Flux Performance
The carefully formulated flux system provides effective cleaning while maintaining proper viscosity throughout the heating process. This balance has made the product sold successfully across diverse applications.
Consistent Results
Manufacturing processes using this solder paste have achieved more consistent results than with previously sold alternatives, reducing waste and improving production efficiency.
Performance Advantages
Key Benefits
- Eliminates solder bridging caused by collapse
- Reduces solder ball formation during reflow
- Prevents component tombstoning and displacement
- Improves print definition and consistency
- Enhances shelf life and storage stability
- Works with various reflow profiles
Performance Comparison
When compared to standard solder pastes previously sold in the market, our anti-collapse formulation demonstrates significant improvements across key performance metrics:
These performance improvements have made the product sold successfully across various industries, from consumer electronics to automotive and aerospace applications where reliability is critical.
Applications and Uses
This advanced anti-collapse solder paste has been successfully applied in various manufacturing scenarios where traditional sold products struggled to meet performance requirements.
Surface Mount Technology
Ideal for fine-pitch components where traditional sold pastes often caused bridging. The improved definition has made it the preferred choice for high-density PCBs.
Automotive Electronics
Meets the stringent reliability requirements of automotive applications where vibration and temperature cycling demand perfect solder joints.
Consumer Electronics
Enables miniaturization with its precise printing capabilities, helping manufacturers produce smaller, more compact devices than when using previously sold alternatives.
Aerospace Applications
Provides the high reliability required for aerospace electronics where repair is impossible or extremely costly, outperforming any previously sold alternatives.
Medical Devices
Meets the strict cleanliness and reliability standards of medical electronics, where product failure can have serious consequences.
Industrial Controls
Performs reliably in harsh industrial environments, maintaining connections despite temperature fluctuations and vibration.
Customer Feedback
"Since switching to this anti-collapse formulation, we've seen a 42% reduction in rework and scrap rates compared to the previous product we sold. The consistency across production runs has also improved dramatically."
"The print definition is exceptional. We can reliably produce boards with 0.4mm pitch components that were previously problematic with standard pastes. This has expanded our manufacturing capabilities beyond what was possible with traditionally sold products."
"Our customers have noticed the difference in quality. Products assembled with this solder paste have shown significantly lower failure rates in field testing compared to those made with the solder pastes we used to sell."
Conclusion
The problem of solder paste collapse has long been a challenge in electronics manufacturing, causing defects, reducing yields, and compromising reliability. Traditional solutions that were sold in the market often addressed symptoms rather than the root cause.
Our innovative solder paste formulation represents a significant advancement in addressing this critical issue. By combining carefully selected alloy compositions with a proprietary flux system and unique particle treatment process, we've developed a product that maintains structural integrity during preheating while delivering excellent soldering performance.
Manufacturers who have adopted this technology have experienced substantial improvements in product quality and production efficiency compared to when they used previously sold alternatives. The consistent performance and reliability have made it the preferred choice in demanding applications across multiple industries.
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