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SigmaTron International Provides Multi-Facility Support to S&C Electric Company

Not many companies today can claim Thomas Edison was a customer, but S&C Electric Company can. Founded in 1911, the company designs and manufactures switching and protection products for electric power transmission and distribution. Headquartered in Chicago, S&C Electric Company has manufacturing and development teams in both Chicago, IL and Alameda, CA. Not surprisingly SigmaTron International’s ability to support both those facilities through its Elk Grove Village, IL and Union City, CA locations was a major factor in the decision for S&C to select SigmaTron International as a strategic manufacturing supplier. Additionally, both companies are strong believers in combining resources to build superior products.

“A significant part of developing a superior quality product is focusing on designing defect opportunities out. The development team at S&C has been very open to implementing the design for manufacturability/testability (DFM/DFT) recommendations our engineering team has made after every design spin. It is great to work with a customer’s design team that is strongly focused on developing a manufacturable/testable design,” said Tony Truppa, SigmaTron’s Program Manager for the project.

SigmaTron’s support team has performed product lifecycle management (PLM) analysis on the bill of materials (BOM) to identify obsolescence risks and suggest alternate parts to broaden the approved vendor list (AVL). The team has also performed DFM/DFT analysis after every design revision and provided a multi-tier, color-coded list of recommendations to prioritize design modification changes by level of impact to either quality or cost.

The product under development is an improvement on a legacy product in the field that includes new features. Sigma-Tron has done several rounds of prototyping and will shortly be building product for accelerated life tests which will expose the product to a wide range of environmental conditions including salt spray, humidity and extreme temperatures. The typical lifespan of these products is often over 25 years.

The current project includes three printed circuit board assemblies (PCBAs) that are assembled into a major subassembly. SigmaTron performs in-circuit test (ICT) on the PCBAs, and then assembles and performs environmental stress screening (ESS) testing and final test on the completed subassembly. The subassemblies are shipped to S&C Electric Company for integration into final assemblies. The next steps after completion of accelerated life testing will be a pilot build and volume production.

SigmaTron’s project team recently met with S&C Electric Company’s development team in Alameda, CA to finalize the initial release of the test vehicle. Prototype boards were tested to deter-mine whether or not the test was measuring test parameters accurately. The teams identified some fixture modification and programming adjustments.
“S&C is an engineering-driven company with the highest degree of quality consciousness that values input from its strategic manufacturing suppliers. Our ability to provide input on the frontend of this project is proactively eliminating issues that otherwise could create production or test challenges and that is very valuable to them.” added Tony.


Union City Facility Provides Multiple Soldering Options

One of the challenges of lead-free manufacturing is that reflow soldering temperatures must be increased to levels that can damage heat sensitive components on the printed circuit board assembly (PCBA). This issue is less of a concern than it used to be because most component manufacturers have modified lead-free component packaging to accommodate higher temperatures. However, there can still be some issues with sensors, connectors or other parts with heat sensitive plastic packaging.

SigmaTron’s Union City (UC) facility addresses the heat sensitivity issue of components by using a low melting temperature solder alloy
using both its conventional reflow oven as well as vapor phase reflow soldering processes.

For example, one of the facilities’ medical customers has a product that involves heat sensitive sensors. Instead of using a manual soldering process, given that manual processes lack repeatability; the UC team, working with the customer’s engineering team, opted to develop a process that would automate it using a tin/silver/bismuth solder with a melting point of 143 degrees C. The low temperature reflow process uses oven temperatures of 175 degrees C +/- 5 degrees, as compared with the 245 degree C +/- 5 degrees process used in conventional reflow. The bulk of the PCBA is reflowed at the higher temperature and then the heat sensitive components are reflowed at the lower temperature. The process also works well for heat sensitive plastics, such as those found in some connectors and specialized parts such as LEDs.

Additionally, the facility has purchased a batch-sized vapor phase machine for products that benefit from that technology. Vapor phase technology provides lower soldering peak temperatures along with more uniform heat distribution because the PCBA is immersed in an inert vapor blanket which permeates all spaces. The ability to control speed of immersion and positioning in vapor blanket minimizes thermal shock and tomb-stoning.
In both cases there are tradeoffs.

“Low melting temperature soldering has its niche applications. Both conventional reflow as well as vapor phase reflow processes could be utilized to help increase our range of high quality, automated soldering options for PCBAs with special challenges, ” said Yousef Heidari, Sig-maTron’s Vice President of Engineering.



Suzhou Facility Receives ISO 13485 Certification

SigmaTron International’s facility in Suzhou, PRC passed the audit for its ISO 13485:2003 certification in April and should soon receive the official certification copy from its regis-trar, SGS.
“Although our robust systems and processes were compliant with the requirements of ISO 13485, we chose to pursue formal certification because we had a local medical customer requesting it. We have a medical project in production now and see a growing market of medical customers within China, so it makes good sense to add the certification,” said HomMing Chang, SigmaTron International’s Vice President China Operations.

The facility is also certified to ISO 9001:2008 and ISO 14001:2004.



SigmaTron’s Taiwan IPO Provides a Wide Range of Support

SigmaTron’s International Purchasing Office (IPO) in Taipei, Taiwan provides a wide range of support to both the Company’s global network of facilities and its customers. The operation utilizes a commodity management strategy. Buyers are broken up by commodity and may have assistant buyers supporting them in larger commodities.
Standard commodities include: semiconductors, connectors, printed circuit boards, magnetics, metal fabricated parts, molded plastics, wound products and transformers, resistors, capacitors, LEDs/displays/LCDs, fabricated modules, relays, sensors, thermistors, switches, audio components, fans, and wires/cables, harnesses. Many of the commodity managers manage multiple commodities.

The same buyers also have direct responsibility for procurement in China and Vietnam.

“When you are regularly negotiating with the supply base for delivered product vs. just contract pricing arrangements, there is an understanding of the deliverables portion of the relationship. We feel having both roles helps keeps our buyers ‘dialed in’ into the issues our local purchasing teams experience,” said John Sheehan, SigmaTron’s Vice President – Director of Materials and Supply Chain.

The team is also active in supplier quality assurance, auditing new fabricated component suppliers as needed to establish a strong initial relationship and ensure they have the required capabilities. Once qualified, supplier performance is measured through incoming inspection and in-process audits at each factory. The IPO tracks cost and performs annual cost reviews. The team takes an exception-based approach to sup-ply chain management with further on-site supplier audits done only if an issue at the supplier indicates an audit is needed.

The facility also has a strong IT staff. In addition to a procurement role, the facility serves as a Green Compliance Service Center, gathering data from suppliers needed to support requirements related to Conflict Minerals legislation, RoHS legislation and other similar initiatives. This data is stored in a database that interfaces with the Company’s other systems.

“One of our key points of competitive advantage is our systems strength and the ability to know where material is located 24/7 via our proprietary iScore system. Having a strong IT function helps ensure the IPO staff has the systems support it needs to be as efficient and responsive as possible,” Sheehan added.

Finally, the team is very active with custom-er support. Buyers play a role in onboarding new customers as part of project launch teams in Suzhou and Vietnam, plus other facilities on an as needed basis. They also are capable of performing a customer service role when customers wish to visit the region or a specific supplier.

“We never forget that the value that we provide customers is primarily driven by our people. Our systems give them visibility, but at the end of the day, they are the problem solvers. We’ve invested in training to ensure they have the knowledge to do their jobs to the best of their ability. As an example, a number of the staff are Six Sigma Green Belt trained. The end result is a knowledgeable team that can pretty much come through any time we ask them,” said Sheehan.

The payback is obvious. The team regularly helps customers identify alternate sup-pliers and cost reductions. In one case, the custom display commodity manager found three alternate suppliers that were 20-50 percent below the cost of the suppliers that the customer had identified. In another case, the team audited a customer-selected supplier that looked very well established on the internet, but in reality turned out to be a small shop incapable of handling the customer’s projected volumes for a custom mechanical part. The commodity manager was able to identify alternate cost competitive sources that could produce in the required volumes.

“The one constant in our supply chain management strategy is that we are always evolving. Our IPO team epitomizes that philosophy. They always do what they
say they will do, even when it has never been done before,” said Sheehan.