Advanced Soldering Technology: Crucial for Extreme Aerospace Environments


■ Example: irradiation position marks (Japan Unix patent).

■ Example: irradiation position marks (Japan Unix patent).

Like many industries, aerospace continues its trend toward more sophisticated electronic controls. This, in turn, drives ever-increasing solder joint density and miniaturization as more and more electronics are packed into smaller spaces. Under normal conditions, these trends present a significant challenge for soldering technologies. To make matters worse, the aerospace industry demands absolute reliability in extreme environments. Japan Unix offers some of the world’s most advanced soldering technologies that help to meet these challenges.

Aerospace electronic equipment must survive the most severe environmental conditions on earth

■ Example: A ring-shaped laser can prevent component burning (Japan Unix patent).

■ Example: A ring-shaped laser can prevent component burning (Japan Unix patent).

Environments are harsh at the edge of space. The temperature is extremely cold, reaching minus 50°C and ultra-low air pressure of 240hPa at altitudes over 10,000 meters. Strong winds rage at over 100kph, in some cases reaching 300kph in the jet stream. Aircraft must be able to safety fly at speeds of 800kph in this unforgiving place.

Like military equipment, aircraft and spacecraft are precision machines built to withstand the most demanding conditions. Their designs must meet the highest engineering, quality and safety standards for components and electronic assemblies.

Highly accurate flight control is of primary importance for communication, navigation, recording and safety systems. Inside the cabin, environmental equipment such as pressurization and HVAC systems are important for passenger comfort. Entertainment systems and food service equipment also add even more electronic equipment, all of which must have high-reliability solder connections that are expected to last, in many cases, for decades.

4Lead-Free solder transition raises issues for aircraft electronics

Aircraft electronics are characterized by thick substrates and large currents. Moreover, components are small and, therefore, susceptible to heat, and difficulties arise when they must be densely placed at narrow pitches. Many Japan Unix customers use laser soldering systems for these reasons. To date, robot and laser soldering have been used primarily on mass production. However, as laser technology becomes more advanced, the technology is becoming an increasingly attractive option for users seeking very high-reliability soldering.

The global aircraft and aerospace market is moving toward 100% lead-free solder. Although, lead-free solder has been successfully applied in home appliances & consumer electronics, the aviation segment has been reluctant to make this change to lead-free due to reliability concerns. However lead solder will be banned in 2018, forcing the global industry to comply.

5Meanwhile, many Japanese manufacturers in electronics and automotive have promoted lead-free soldering since the inception of RoHS in 2006, and by now have almost completely transitioned to lead-free. Japan Unix has accumulated significant expertise in lead-free robotic soldering, working with its customers who lead their respective industry sectors. In particular, major clients in the automotive and industrial machinery sectors have products that are used in environments whose harshness is second only to aerospace or aircraft. This soldering expertise is now being applied by many aerospace and aircraft industries.

How to apply effective laser soldering

In order to automate the soldering process by adopting laser technology, a manufacturer should be prepared to use a combination of the following three technical capabilities:

1. Distinct knowledge of lasers

■ Example of Analysis: Comparison of compositional changes in solder according to soldering temperature.

■ Example of Analysis: Comparison of
compositional changes in solder according
to soldering temperature.

2. Soldering expertise

3. Robotic integration & control

A conventional soldering iron and a soldering laser are based on different concepts of heat transfer. A soldering iron conducts heat, but a soldering laser generates surface heat.

When metals such as tin, silver or copper are soldered, flux or other chemical substances promote a chemical reaction upon heating, after which they solidify. Solid metal is melted and flows into through-holes or along a surface to form a solder fillet. To achieve proper and consistent soldering forms, optimal soldering designs are required. Solder joint design should consider conditions such as landing pattern, component geometry, material and desirable thermal capacity.

Automation of these optimally-designed soldering conditions requires translating them into robotic operating commands and programming, which takes unique expertise. Automated soldering processes include adjusting a heat source (soldering iron or laser), feeding the solder, and providing controlled heat (via an iron tip or laser irradiation). In addition to its soldering design expertise, Japan Unix owns numerous critically important technical laser soldering patents. For example, Japan Unix owns a patent for laser irradiation position marking that is widely regarded as the first step in the process of developing robotically soldered joints. Other related patents include solder feed and position calibration, which ensures that Japan Unix technology provides industry-leading laser soldering capabilities.

Optimizing laser shapes for each component’s geometries

To support complexities in recent electronic components and assemblies, Japan Unix has uniquely developed a multi-phi laser as new laser soldering technology. In conventional laser soldering, the irradiation diameter is fixed, but in the multi-phi laser, the diameter is automatically changed to match the component shapes and land patterns.

If the irradiation diameter is fixed on a substrate where large and small components are placed, the diameter will be adjusted to the smallest one, but the heating capacity will then become insufficient for the largest components. As a result, the irradiation time must be longer, and that may inevitably impact production efficiency and quality. Automatically changing the diameter every instant can provide optimal soldering conditions for each component.

When contact soldering, the optimal iron tip is selected for soldering each component. Equivalent changes are accomplished by changing laser diameter or shapes. And even beyond its variable-diameter lasers, Japan Unix also can propose specially optimized variant laser shapes that include ring, square or oval.

Global standards for the aviation and aerospace industry

In 2015, Japan Unix established a partnership with IPC, and is supporting its expansion in Japan. IPC brings global manufacturers standardization for each production process. In the 1980s, the MIL standards were transferred to IPC, and since then they have been updated and managed as IPC-J-STD. Top global organizations such as NASA, BAE Systems, Boeing, Airbus and GE together develop and adopt IPC standards.

IPC fully recognizes J-STD-001 as a globally-accepted soldering standard, and it has been adopted by worldwide electronics companies. Meanwhile, the soldering quality required by the aerospace industry, described above, has criteria that differ from the requirements of other segments. Therefore, IPC has established a J-STD-001(S) as a special standard that defines additional aerospace-specific requirements. Japan Unix is able to quickly obtain industrial updates and the latest requirements as the IPC’s official partner in Japan.

Japan Unix Soldering Lab & School

Japan Unix organizes a soldering lab to scientifically analyze soldering and operates a school to educate soldering technicians. A large number of highly-skilled soldering engineers have been internally trained to provide soldering advice for our customers. The latest assemblies are brought to the lab from all over the world to be tested and analyzed with soldering robots. These relationships help Japan Unix to accumulate a wealth of knowledge in soldering and automation.

If there is even one soldering mistake, the entire product becomes defective. It cannot serve in a safety-critical function in aerospace equipment, whose defect will directly influence human lives. Japan Unix’s accumulated knowledge is shown in quantitative data and, thus, we can propose scientific solutions to customers. At the same time, our experienced engineers can take an approach to solve soldering issues with both quantitative and qualitative factors.

Japan Unix has been gaining actual results and data from soldering robots and automation experience for decades. This experience applies most directly to automotive, but is adapted to other industries, such as the medical, aviation and space segments. We also have significant experience in the aviation and space industries where we have longstanding partnerships with ITAR-compliant distributors such as Fancort Industries in North America.

Therefore, Japan Unix has come to be seen as the only soldering robot provider for electronics made to operate under the harsh conditions where humans cannot act.

Other examples

1. Ultrasonic soldering may be used to solder aluminum and glass materials for aircraft instrumentation and flight equipment.


2. The UK National Physical Lab (NPL), the leading measurement institute, analyzed Japan Unix laser soldering samples and proved its high quality.

3. Japan Unix conducted research about how inadequate laser irradiation diameter leads to soldering defects.

4. Japan Unix soldering lab analyzes the growth of soldering composition (right).


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