The implementation of the European Union’s RoHS directive mandatedthe use of lead-free solders in the electronics industry by 2006. However,five years before, Japan’s appliance recy-

cling waste electronic and electrical equipment(WEEE) regulation went into effect. This regula-tion covered home electrical goods, air condition-ers, refrigerators, freezers, TVs, washingmachines, and clothes dryers.

A new category of waste type, a category thatincludes precious metals, as well as such toxic sub-stances as lead (Pb) and polybrominated biphenyls(PBBs) was included in the WEEE regulation. Forthe solution to replace tin-lead solder, the industrylooked to lead-free alloys, includingtin-copper (SnCu).

But, the SnCu did not performas expected as a eutectic solder. Theindustry was forced to researchimprovements to turn SnCu into auser-friendly solder.

The Birth of SN100C

In 1998, Tetsuro Nishimura, thenNihon Superior’s technical manager,now CEO, in partnership with theaudio and video division of PanasonicCorporation extensively investigatedthe causes of the poor performance ofSnCu. Nishimura identified nucleationof the second phase of the eutecticCu6Sn5 as the problem.

Adding a trace amount of nickel,0.05 percent, was discovered as themost effective method of enhancing theperformance of the solder. Duringsolidification, nickel works by facilitat-ing the nucleation of the intermetallicCu6Sn5, making it possible to solidifyas a eutectic, such as tin-lead solder.

With the microalloying of nickelto SnCu, SN100C was born. Duringthe development, a germanium (Ge)addition was identified as the mosteffective way to control the oxidationthat generates dross.

Nishimura was awarded “BestInventor” by SMT Today magazineduring the 2015 SMTA Internationalconference and exhibition in recogni-tion throughout the electronicsindustry as the inventor of SN100Cand the pioneer of microalloyed sol-ders.

This award recognizes an indi-vidual or team whose innovationshave not only addressed a need andsolved a problem, but also have beenused to drive improved efficiency, pro-ductivity and performance within theelectronics manufacturing industry.

“The small amount of nickel islike the effect of salt in a dish. Asmall amount has no taste, no effect,but a large amount overpowers thedish, ruining the taste. A good dishrequires the right amount of salt, justas SN100C has the right amount ofnickel. On the other hand, germani-um is like pepper, which gives a goodtaste, but the amount may be varied,”says Nishimura.

Commercial Debut

The first commercial use in massproduction for the newly developedSN100C solder was in 1999 for aPanasonic VCR. Since then, SN100Chas been widely accepted and hasgained a reputation as a reliable solder.

The reliability of SN100C hasbeen proven in a wide range of elec-tronics assembly products, fromappliances to industrial, automotiveand aerospace. The alloy delivers asilver-free stable microstructure that

can accommodate the long-term and impact strains to which a solder joint canbe subjected. The eutectic character of SN100C alloy and the associated high

fluidity provides faster wetting and increasedspreadability over SAC305, which is beneficialin wave and hand soldering applications, as wellas in reflow.

Due to the significant increase in eco-friendly hybrid and electric vehicles, the demandfor solder joints to resist thermal fatigue is alsogrowing. Vehicles are often exposed to extremetemperatures during service and the solder mustfunction in a range of environments.

July, 2019 Page 63www.us- tech.com

SnCu (left) and SN100C (right).

SN100C Achieves 20 Years of Reliable Service

By Keith Howell, Technical Director, Nihon Superior USA

Continued on page 69

knowledge. Tribal knowledge is information aboutprocesses, methodologies and more that is storedonly in certain employees’ memories. This informa-tion is unwritten, but is often critical to successful-ly implementing a process, creating a product ormaintaining quality levels.

Employees that change roles or leave thecompany will take this information with them,undermining the process or product they onceoversaw. This presents a real risk for many compa-nies, harness manufacturers included. Ten thou-sand Baby Boomers retire every day in the U.S.

In Canada, from 2011 to 2016, there was a 20percent increase in the number of Canadians thatreached the age of retirement. In the U.K., it is pre-dicted that between 2016 and 2020 the number ofpeople between 16 and 49 will decrease by 700,000.

The workforce is shrinking. How can managersmaintain productivity with a younger, less-experi-enced and smaller workforce? In par-ticular, how can they capture the vitalinformation and expertise held bytheir current employees to prevent acatastrophic loss of tribal knowledge?

In a typical, high-level, wireindustry, manufacturing engineeringflow, design engineering first releasesinitial designs or engineering changesfor costing and to provide quotes to thecustomer. Next, the main formboard isdesigned, followed by production mod-ules and subassemblies, which occa-sionally require their own assemblyboard. Then, the engineers will designa bill of process (BOP) for the entireharness, allocating wires, splices,twisted wires, and all remaining mate-rial to its designated equipment orworkstation.

The BOP is then released intothe enterprise resource planning(ERP) system. This is followed by bal-ancing and optimization of the finalassembly carousel and then creationof the work instructions.

Introducing Error

Errors from data reentry canoccur at any of these stages, each ofwhich requires great skill and experi-ence. Adjustments and correctionsmade downstream in the flow mustbe fed upstream manually in order toachieve data coherency.

The conventional wire harnessmanufacturing methodology is vulner-able to errors from fragmentedprocesses and the loss of tribal knowl-edge as engineers retire or leave theirjobs. Other key issues include inconsis-tent or inaccurate costings, suboptimalformboard design or manufacturingprocess design, as well as misplacingkey information on the shop floor.These can lead directly to inefficiencyduring production. As a result, manu-facturing and overall costs can over-shoot the quote made to the customerand production quality can suffer.

Model-Based Engineering

A model-based flow unifies thepreviously fragmented domains ofdesign and manufacturing byautomating data exchange and pro-viding engineers with access to cross-domain decisions. Tribal knowledge,previously held by experienced engi-neers, is captured through integrateddesign rules that support automa-tion, guide all engineers consistentlyand check designs for issues.

There are three key aspects todigitalization and the model-basedenterprise in the wire harness indus-try. First are digital models of thewire harness product and the manu-facturing process. The digital modelsof the harness and production processtogether create what is known as a

“digital twin.”Automation is the second key aspect. Today’s

harness design and manufacturing solutions canconsume design rules created by veteran engineersand use them to automate the transformation ofthe digital harness and process models into BOPs,

work instructions and other output formats. Thissimultaneously embeds tribal knowledge into thecompany’s production flow, safeguarding it fromemployee turnover.

The third aspect is data reuse. Instead ofrecreating or reengineering data, in a model-basedengineering flow, data is created once and reusedto the greatest extent possible by all upstream anddownstream consumers.

In a digital world, companies create a digitalthread in which all of the functions, from architec-tural and functional design through to physicaldesign, manufacturing engineering and after-salesservice, can all use the same data. At each stage ofthe harness lifecycle, each stakeholder can use thesame data models and have access to decisionsthat are made in other domains. Using a digitalthread, design cycles are faster and issues can becaught and resolved earlier in the process when

July, 2019 Page 67www.us- tech.com

The three key tenets of a model-based

enterprise: digitalization, automation anddata reuse.

Model-Based Engineering for Wire Harness ManufacturingContinued from previous page

Continued on page 69

In a thermal cycling test, it was shown thatthere are significant differences in the reliability ofSN100C versus that of the Sn-3.8Ag-0.7Cu alloy.After 2,000 cycles, cracks started to appear. At4,000 cycles the alloy failed completely. In the sol-der joints made with SN100C, there was no signif-icant cracking until 4,000 cycles.

Nihon Superior’s Heritage

Nihon Superior has been a leader in solderingand brazing since it was founded in 1966 byToshiro Nishimura and continues its tradition ofdeveloping lead-free joining materials withimprovements in reliability, thermally stable join-ing and lead-free die attach. Toshiro’s son,Tetsuro, now runs the company and Toshiro’sgrandson, Takatoshi, is also involved in the com-pany, making Nihon Superior a third-generationfamily-owned business.

The company continues todevelop highly reliable products andis committed to earning its cus-tomers’ highest level of trust by tak-ing full responsibility for every prod-uct delivered. The company remainsready to meet rising demands fordiversification, increasingly sophisti-cated technologies and environmen-tal protection.

Beyond SN100C

It is becoming increasingly ap -parent that the simple ternarySAC305 alloy cannot deliver every-thing that the electronics industryrequires from a solder, in terms ofcost and performance. The cost of thethree to four percent silver requiredto get the 422.6°F (217°C) solidustemperature was one of the main rea-sons for choosing SnAgCu eutecticthat had reduced silver content aslow as 0.1 percent, or even withoutsilver altogether.

Nihon Superior has now devel-oped its SN100CV alloy that gains itsstrength from solute atoms in the tinmatrix of the joint unlike silver-con-taining alloys that derive theirstrength from a dispersion of fineparticles of eutectic Ag3Sn. The addi-tion of bismuth enables thermallystable solder joints, even after ther-mal cycling.

Another product the company has developed isthe Alconano silver sintering paste, which is basedon a patented technology that makes it possible to

effectively join most metals, as well as silicon and sil-icon carbide at low sintering temperatures, in nitro-gen if necessary, without the nitrous or sulfurousresidues that are the byproducts of the sintering ofsome other nanosilver pastes. The highly active sur-face of the nanosilver particles and the consequentstrong capillary forces make it possible to achievestrong bonds with high electrical and thermal con-ductivity at low temperatures, without the needfor external pressure.

Twenty years ago, when SN100C was invented,it was considered to be a reliable and stable alterna-tive to SnPb solders. Now, its reputation has growneven stronger and has evolved to meet new industrychallenges.

Contact: Nihon Superior USA, LLC, 1395 Hawk Island Drive, Osage Beach, MO 65065 E-mail: k.howell@nihonsuperior.co.jp Web: www.nihonsuperior.com r

July, 2019 Page 69www.us- tech.com

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SN100C Achieves 20 Years of Reliable ServiceContinued from page 63

Three generations of the Nishimura family (from left): Takatoshi, founder

Toshiro, and CEO Tetsuro.

they are much less expensive. Byalso reducing design rework, datareuse minimizes costs and enablessuperior manufacturing efficiency.

In order to survive and grow inthis challenging environment, harnessmanufacturers must significantlychange their methods. Digitalizationis a key adaptation for harness mak-ers, offering the tools needed to sur-vive in an extremely dynamic indus-try. A digital model-based flow unifiesthe previously fragmented domains ofdesign and manufacturing and cap-tures tribal knowledge held by experi-enced engineers through integrateddesign rules. To meet the demands ofan evolving industry, it is time for wireharness makers to become digitalenterprises.

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See at SEMICON West, Booth 2335

Model-BasedEngineering...Continued from page 67

See at SEMICON West, Booth 1534