Manufacturing / Production Technology, Hardware & Services


Soldering tips for the 'lead-free' process

26 July 2006 Manufacturing / Production Technology, Hardware & Services

Soldering is based on the ability of different metals to dissolve or diffuse into each other and to cause an electrical connection at lowest resistance and mechanical fixing. Flux is used to dissolve metal-oxygen layers on the surface of the different metals being connected with each other due to the dissolving of the tin into them.

Soldering tips

A soldering tip has two major tasks. The first is to transfer thermal energy with as low a loss as possible, and secondly, to carry the solder on the joint in combination with flux. Due to physics, the tip turns out to be a wearing part. And these tasks have to be done in combination with achieving long lifetime and at lowest cost.

To achieve excellent thermal conductivity, a soldering tip consists of a copper core (silver would be better, but is much more expensive).

The wettability of copper with solder tin is extremely good, which means the solubility of copper in solder tin is extremely high, causing the tip to be quickly consumed. The tip must be wettable to properly carry the heat and the tin on the soldering joint. Iron is also wettable with tin, but the solubility is far less. Unfortunately iron has a very low thermal conductivity and hinders thermal flow. The thicker the iron layer, the lower the heat transfer from the tip towards the soldering joint. The thinner the iron layer, the shorter the lifetime due to the solubility of iron in tin. Using other materials that are not soluble in tin will cause a non-wettable tip and poor soldering results.

Heating tips to high temperatures

The aggressiveness of the solubility of iron into tin increases with rising temperature. So also, the mechanical resistance of the tip's iron layer is reduced. When soldering, the tip is somehow always touching some part of the component and is in contact with the aggressive tin. Now, with lead-free soldering, the content of the tin in the solder is increased by 35%. This results in a 35% more aggressive solder towards the iron layer, simply causing reduction in life.

Now, standard tips have an average iron layer of 200 μm depending on the geometrical form. Weller's new LF tips carry an optimised layer of twice as much iron. More iron would cause a lower heat transfer and hinder the soldering process. Influence of the temperature to the lifetime and iron layer can be seen in Figure 1.

Figure 1. The graph shows that the LT-LF soldering tips provide a cost reduction and that the main influence to tip lifetime is the soldering temperature
Figure 1. The graph shows that the LT-LF soldering tips provide a cost reduction and that the main influence to tip lifetime is the soldering temperature

A general recommendation is to use a tip as large as possible, and if necessary, to improve the process by using a thinner solder-wire. For lead-free solder, the adjusted soldering temperature at the station should be in the range of 340-360°C, depending on the geometry of the tip. For further enhancement of tip lifetime 'Stop+Go' stands should be used.



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Case study: Fast and efficient cable harness component picking and traceability
Manufacturing / Production Technology, Hardware & Services
An automated robot manufacturer can now easily trace every component used in cable harnesses for robotic arms, with industrial labels and a custom scan and print application from Brady.

Read more...
New handle for the XP Series joystick
Brabek Manufacturing / Production Technology, Hardware & Services
The new MF handle meets market demands to combine a traditional compact design with multiple functionalities and customisation options.

Read more...
Next-level conformal coating
Techmet Manufacturing / Production Technology, Hardware & Services
The ASYMTEK Select Coat SL-1040 Series is Nordson Electronics Solutions’ most advanced conformal coating solution for high-volume production.

Read more...
The impact of ML in robotics
Manufacturing / Production Technology, Hardware & Services
The integration of machine learning into robotics has the potential to revolutionise many industries, and particularly the manufacturing sector.

Read more...
ITW EAE wins product introduction award
Allan McKinnon & Associates Manufacturing / Production Technology, Hardware & Services
ITW EAE has earned a 2024 New Product Introduction (NPI) Award for Electrovert’s Deep Wave option for wave soldering machines.

Read more...
Revolutionising clean air in electronics manufacturing
Allan McKinnon & Associates Manufacturing / Production Technology, Hardware & Services
Designed to prioritise clean air in the electronics manufacturing industry, the ZeroSmog Shield Pro sets a new standard for workplace health and safety.

Read more...
High-speed multi-function dispensing
Techmet Manufacturing / Production Technology, Hardware & Services
The D-VIS and DL-VIS from GKG SMT printer specialists are high-speed dispensing systems that can handle multiple scenarios.

Read more...
Optical inspection for SMT
Techmet Manufacturing / Production Technology, Hardware & Services
The Xpection 1860 from Scienscope is a versatile X-ray inspection machine that offers comprehensive circuit board defect detection and quality assurance for the SMT industry.

Read more...
Yamaha introduces upgrades to its 3D AOI systems
Truth Electronic Manufacturing Manufacturing / Production Technology, Hardware & Services
Yamaha Robotics SMT section has revealed performance-boosting upgrades for the YRi-V 3D AOI system, including faster board handling, multi-component alignment checking, and enhanced LED coplanarity measurement.

Read more...
Flexible printed electronics substrates
Manufacturing / Production Technology, Hardware & Services
New LEXAN CXT film from SABIC offers high thermal process stability and transparency for demanding printed electronics substrates.

Read more...