Uchihashi Estec – Manufacturer of the Elcut brand of Thermal Cutoff Fuses

thermal cutoff fusesUchihashi Estec manufactures thermal cutoff fuses (Elcut brand) and solder products (solder bars, solder wires, flux cored solder wires, solder paste, solder fibers, solder ribbons and fluxes). Uchihashi Estec is fully committed to quality products and environmentally safe manufacturing processes. The company employs approximately 100 employees and has ISO 9001 certified manufacturing sites in Japan and Vietnam.

thermalcutofffuses1Uchihashi Estec began manufacturing and marketing solder products in 1918. For nearly a century, the company has been leading the development of the most advanced alloy technologies – including the successful commercialization of the world’s first small alloy thermal cutoffs. Uchihashi’s thermal cutoffs and solders may not always be visible to consumers, but they ensure the safe and reliable operation of a wide range of electrical products in which they are incorporated.

Key Milestones

thermal cutoff fuses

Don’t Get Fooled Into Buying Counterfeit Thermal Cutoff Fuses

thermal cutoff fuses

As we begin a new year it’s important to always be aware of the possibility of counterfeit electronic components — even inexpensive thermal cutoff fuses. Some of the largest and most trusted thermal cutoff fuse makers discovered that cheap counterfeit fuses were being illegally sold. The counterfeits being distributed have not met Safety Standards and may not operate properly.

These problems could largely be avoided by only dealing with authorized distributors, but there is a growing pressure for smaller manufacturers to cut costs.

As of November 2015, the U.S. Bureau of Labor Statistics found that 7,791 electrical manufacturing establishments employed 371,700 people. One of the biggest issues that U.S. manufacturers have faced in recent years is the average 20% structural cost burden they face compared to overseas competitors, and many companies are looking for ways to lower operational costs. While there are ways manufacturers and electrical engineers can cut costs, thermal cutoffs shouldn’t be one of those ways.

NEC SCHOTT (maker of SEFUSE brand thermal fuses) confirmed that counterfeit thermal cutoff fuses were being sold in the Chinese market. These SEFUSE thermal fuses were sold with the official NEC SCHOTT logo and other familiar branding, but came with a “high risk that [they] can lead to serious accident.”

Before purchasing thermal cutoff fuses for use in your products, make sure you’re working with an authorized distributor, otherwise you could end up working with counterfeit thermal fuse suppliers.

We have also been informed that counterfeit thermal cutoffs using the Elcut brand have been found in the Chinese marketplace. This time, counterfeiters weren’t just using the official Elcut logo, they were also posing as official distributors to Chinese buyers.

Always purchase safety equipment and fuses from official authorized distributors, and never from overseas or bulk auction websites. Counterfeit thermal fuses might look the same at first glance, but may be of poor quality and may not operate as expected.

Thermal fuses for manufacturers have to work as designed and at the rated cutoff temperature. While we haven’t yet received any reports of counterfeit fuses here in the United States, anyone who plans to use thermal fuses in 2016 should take care to work with only a legitimate thermal fuse company and trusted, authorized suppliers.

Bending Lead Wires – Cautions

Improper bending of the lead wires on a thermal cutoff could result in improper functioning of the TCO. Both Uchihashi and NEC/SCHOTT, the manufacturers of the Elcut and SUFFUSE brand of thermal cutoffs provide detailed cautions on lead wire bending and should be strictly followed.

Since the SEFUSE SF thermal fuses operate differently than the Elcut brand, the lead wires bending cautions are slightly different.

Improper lead bending/handling include

  1. Cracked or broken seals on the lead wire/body junction
  2. Broken lead wire-to-thermal element welds
  3. Damaged fuse bodies

NEC/SCHOTT SEFUSE brand (Cautions from NEC/SCHOTT):
When bending the lead wire, it is important not to apply excessive pressure to the root of the lead wire. The lead wire should be secured close to the case and bent (not twisted) at a distance 3 mm or more from the body of the fuse. It is important to secure the lead during bending so as to prevent excessive forces on the TCO body and lead-wire to body connection. The fuse body should never be exposed to crushing forces,

thermal fuses

The tensile strength applied to the lead wire should be 49N or less for SF types.

The force applied to the body of the thermal cutoff should be 98N or less for SF-type. With regards to the SF-type, deformation of the case may change the location of the sliding contact during operation and could lead to the thermal cutoff operating only at temperatures lower than the normal operating temperature range. The thermal cutoff may also not operate even if the thermal cutoff’s operating temperature is exceeded.

If using SF-type thermal fuses, the lead on the resin-sealed side must not be allowed to touch the case since the case is electrically conductive. This would cause the current to flow from the lead on the resin-sealed side to the opposite lead resulting in a non-functioning thermal cutoff.

thermal fuses

Note that the body of the SF-type is the same in potential as the circuit. Therefore, it must be electrically isolated from other metallic parts.

Uchihashi Elcut brand Thermal Cutoff Installation
Caution to be observed when installing thermal cutoffs

    • Do not twist the body or lead wires (i.e. do not turn or rotate lead wires respect to the body). This could result in breaking the lead wire-to-thermal element weld or may compromise the epoxy seal.
    • Do not push lead wired toward, or pull them away from the thermal cutoff body at axial stresses exceeding those shown in Table 1 (room-temperature reference values). Values in Table 1 were calculated from lead wire diameter according to IEC60691.
    • Tangential forces on the leads must be avoided (i.e. pushing or pulling on the leads at an angle to the thermal cutoff body) as such forces may damage the thermal cutoff’s seals.
    • When bending a lead wire for installation, fix the part of the lead between the body and the lead section to be bent using a tool, and gently bend the lead section that is at least 3 mm from the body. Never hold the body with a tool.
    • Do not damage lead wires by holding with a sharp instrument, and do not bend at a sharp angle.

thermal fuses

  • After a thermal cutoff has been connected, do not apply excessive force that will crush the thermal cutoff body, sealant, or lead wires, and ensure that leads are not subjected to tension, pressing, or twisting forces with respect to the thermal cutoff body
SeriesMaximum TensionMaximum Pressure
32, 44, U2, S4.4N1.1N