Trending topics and troubleshooting tips from Hakko

1. What are Hakko’s ‘Trending Tech Tips’ - the questions you receive most repeatedly?

•  Why do I need to use the Hakko Cleaning Wire rather than the traditional damp sponge for tip cleaning? The simple answer to this is as follows: For tin/lead soldering the traditional damp sponge is perfectly adequate. However, in the advent of lead-free solders, the water in the sponge increases the rate of oxidation of the soldering tips, which is already high due to the absence of the lead content in the alloy. The cleaning wire is much more aggressive and contributes to removing the oxide layer before it becomes a hindrance to the soldering process.
• What temperature is best for soldering? There is no ‘one size fits all’ answer to this question. The set temperature of a soldering iron is very much dependant on the solder alloy being used and thermal characteristics of the component and PCB being soldered. Care should be taken to select the soldering station offering the lowest temperature, prevent prolonged contact, excessive heat and potential damage to the assembly.
• How do I make my solder tips last longer? Regularly maintaining the cleanliness of your soldering tip will prevent you having to replace them so frequently. If the oxidisation on the tip is not too extreme, maintenance can be simply carried out by using HAKKO’s 599B Tip Cleaner. The 599B is made up of brass wire so you can easily work the tip to remove most of the oxides. The brass wire can also be easily replaced once they have been well-used. For re-tinning soldering tips and removing oxidisation, the HAKKO FS-100 chemical paste is an essential workstation companion. Heat the oxidised tip to +350°C, then tin the soldering tip, clean off the FS-100 paste with any HAKKO tip cleaning sponge or the HAKKO 599B cleaning wire and check if the tip surface wets or not. This process may need to be repeated numerous times until the tip surface wets. Re-tinning is now complete but to prevent re-oxidisation it is advisable to apply sufficient solder to the tip when soldering work is completed. After finishing work it is also good practice to clean the tip and apply new solder to the end of the tip.
• Why do I need to calibrate my solder tip temperature? All soldering equipment is subject to variation in set-point temperature. This will be due to inherent equipment design and thermocouple tolerances. Oxidation build up and even operator error are also likely to be contributory factors. To ensure that the temperature of the solder tip is as shown on the display, use of a separate Digital Thermometer, such as the Hakko FG100B, is required. This will provide an accurate comparison temperature from where a temperature offset can be programmed into the solder station and ensures that the display temperature is actually the true temperature of the tip. The aforementioned is especially important in high reliability applications such as MoD, aerospace and medical assemblies.

2. What are the most common misconceptions about soldering?

• Given full control, most operators will set pretty much any programmable soldering equipment to the maximum temperature possible. This is only for the benefit of speed and offers no advantage in terms of the integrity of the solder joint produced. The whole process of soldering is reliant on three main elements, i.e. the transfer of heat from the solder tip to the componentry to ensure that both parts are at the optimum temperature, which will activate the flux in the solder wire. This process allows the surfaces to be soldered to be cleaned and prevents any further oxidation, enabling the solder alloy to melt and flow, and finally, allowing the subsequent cooling of the joint. High set temperatures will also reduce the life of any soldering tip.
• Incorrect selection of the optimum tip. Selecting the most accurate size of tip will significantly improve soldering performance and reduce costs. There are numerous benefits to getting the right-sized tip. Firstly, heat will be more efficiently transferred to the workpiece, which offers easy wetting by the solder. When wetting by solder is easy, the setting temperature can be set to the lowest possible temperature, which in turn prevents tip oxidation and potential damage to your product. This will consequently prolong the service life of the tip and keep manufacturing costs down in the long-term. The size of the tip changes the contact area with the workpiece and the contact area determines how efficiently heat is transferred to the assembly.
• So, what size tip will transfer heat the most efficiently? The larger sized tips have a higher thermal capacity and will maintain their temperature better when working on large contact areas, however, they will be too big for many applications. Smaller tips are more versatile and easier to use for numerous different applications, however, they will tend to cool down when presented to a large contact area. Not selecting a correctly sized tip is a common mistake that is easy to make, as choosing a tip that’s too small will result in insufficient heat being transferred whilst choosing an oversized tip could result in damage to the PCB and/or component. As a rule of thumb, selecting a tip with the largest amount of heat storage at the appropriate size will, importantly, eliminate temperature reduction of the tip during soldering and facilitate operation at a lower temperature set point. Potentially, this could also reduce the time taken to produce a good quality solder joint. For instance, a lower set point for a shorter period of time will result in significantly reduced tip oxidation and longer tip life. Therefore, select a tip with the highest heat storage capacity possible if the size is the same. Additionally, reduce the size gradually considering various conditions such as narrow pitch.

3. What is your go-to resource when things go wrong? – i.e. perhaps a problem with temperature or a recurrent error?

Do you have a trouble-shooting manual or is it years of experience? Ultimately, there is no substitute for training and experience, however, there is obviously a wealth of information and support available to eradicate any problems. If there is a problem with equipment, the instruction manual or manufacturers website is a good place to start. If a resolution still cannot be found, then it is time to make direct contact with your equipment supplier. If it is a process problem, then we would suggest that in the absence of on-site Engineering support, customers should contact their component, soldering material and/or equipment suppliers. However, in Hakko’s opinion, most soldering issues are usually attributable to poor quality, oxidised or damaged components.

In this instance, any reputable supplier should be able to provide additional services, e.g. Solderability testing, Cross-sectional analysis of solder joints, etc. One or all of these should be able to highlight any root cause and point the way to any corrective actions that need to be taken. If an impartial opinion is required, then the aforementioned services can be requested via an independent body, e.g. International Tin Research Institute, at an additional cost. And finally, if it is an education/training issue that is the underlying cause of any issues, there are certified organisations that can provide formal training, e.g. IPC Soldering Training, etc.

4. What is one of the most common things to get wrong when starting out?

As financial resources are at a premium at this stage of a businesses’ development, the temptation is to go down the ‘cheap and cheerful’ route. Easy to say but this is usually false economy when examined in the medium to long term. This would apply to not only soldering equipment but also soldering materials. More reputable suppliers can offer well developed products and significant support to any fledgling business. Rework is often overlooked within a new business too. Without doubt, this a highly skilled discipline and the more basic the tools deployed, the higher the skill level will be to complete the task at hand without damaging the PCB/Component.

5. What do you find are the most useful resource guides – how-to videos, books, blogs, trouble-shooting columns/guides etc.?

Word of mouth and personal relationships have always been the best form of resource. However, there is such a lot of information available on the internet now (YouTube, etc.), that most projects can be researched satisfactorily. However, blogs/vlogs should be treated with a certain amount of caution as the information provided is heavily influenced by an individual’s opinion. As highlighted above, most reputable suppliers publish technical papers, videos on the internet and/or their own websites. Alternatively, industry recognised forums, such as the SMART Group, are reliable sources of information based on the experiences of other individuals and companies in the Electronics industry.  

Sustaining a regular daily maintenance regime in a clean, dry and well-ventilated area will also ensure that Hakko equipment stays in tip top condition. For soldering stations, a periodic check of leak voltage, tip-to-ground resistance and tip temperature are also advised. To prevent device damage and soldering failure, periodically perform these inspections either daily or weekly. Hakko hope this month’s tech tips have helped and been of interest.