What is the „nickel drop“ in selective soldering?
The term „nickel drop“ describes the formation of intermetallic precipitates during the soldering process. These are caused by chemical and physical interactions between:
- the solder alloy (e.g. Innolot)
- the surfaces of components and printed circuit boards
- the set process parameters
This results in non-uniform solder joints, which exhibit poorer mechanical and electrical properties. This is a critical factor, particularly in applications subject to high loads.
Why does „nickel drop“ occur during Innolot processing?
The occurrence of „nickel drops“ is not usually attributable to a single factor, but rather to a combination of several influences.
Common causes include:
- incorrect process parameters or process sequences
- inadequate thermal management
- incompatible combinations of materials
- inappropriate product design
However, the most important factor remains the process control. Only when all parameters are precisely calibrated can Innolot be processed stably and the „nickel drop“ be avoided.
Technological solutions to prevent „nickel drop“
For decades, EUTECT has relied on targeted technological approaches to prevent „nickel drop“ in mini-wave soldering.
As early as 1989, the first mechanically pumped high-temperature soldering modules, featuring specially developed materials and coatings, were put into use. These prevent undesirable interactions between the solder and the system components.
Key measures are:
- Use of non-wettable soldering nozzles
- Use of special coatings for tanks and components
- careful selection of materials to prevent alloying reactions
This combination ensures that no intermetallic precipitates form, even at high temperatures.
Reliable processes thanks to state-of-the-art soldering and pumping technology
Another key to stable Innolot processing lies in the plant technology.
The development of mini wave soldering modules with horizontally integrated induction pumps reduces deposits within the system and ensures a uniform flow of solder. This significantly improves process stability.
In addition, a flexible control system ensures optimised operating conditions:
- Targeted switching on and off of the solder pot
- Use of standby mode
- Reduction of thermal stresses
This results in less wear and tear, whilst at the same time reducing the consumption of energy, nitrogen and solder.
What temperatures are suitable for Innolot?
Processing Innolot requires stable processes, even at high temperatures. Modern systems enable a wide range of applications:
- Standard processes up to approx. 350 °C
- extended applications up to around 480 °C
- mechanically pumped systems up to 550 °C
The soldering nozzles used are also designed for these temperature ranges, which ensures long-term process stability.
Composition and specific properties of Innolot
Innolot is based on the lead-free SAC305 alloy, but is optimised with additional elements. These specifically influence the properties of the solder joint.
Key components are:
- Bismuth (Bi) to lower the melting point and increase strength
- Antimony (Sb) to improve creep resistance
- Nickel (Ni) to increase resistance to oxidation and optimise intermetallic formation
This complex composition necessitates precise process control in order to ensure high-quality solder joints and to prevent „nickel drop“.
How to avoid „nickel drop“ when processing Innolot
The safe use of Innolot in selective soldering requires the precise coordination of process parameters, materials and equipment.
EUTECT demonstrates that the „nickel drop“ can be effectively prevented through innovative technologies, optimised process control and the careful selection of materials.
The result is stable, reproducible processes and consistently high-quality solder joints, even under demanding conditions.
