pdf_downloadDownload a PDF of this issue with color photos

Union City Team Honored As Platinum Supplier for Third Consecutive Year

For the third year in a row, SigmaTron has been honored as a Platinum Supplier to St. Jude Medical’s MCS Division, the world leader in mechanical circulatory support systems for humans. SigmaTron’s Union City facility supplies printed circuit board assemblies (PCBAs) used in the Heart Mate LVAD’s battery pack. This is a system that is used to keep patients alive while they are waiting for a heart transplant. It has been so successful that patients can live with the system for years. The award was based on a combination of on-time delivery, quality and service performance.

On Sept. 19th, the Union City facility’s Quality Manager Brad Brouillard and Program Manager Bill Bratton represented SigmaTron at St. Jude MCS Division’s Supplier Conference in Pleasanton, CA, where participants were given an overview of the division’s supply chain plans and goals. The awards were presented at a dinner held that evening.

“It is very humbling to be part of team supporting a product that helps change lives for the better. And, it is a pleasure to work with a customer team that truly is focused on superior quality from design through production,” said Bill.

“Our Union City team continues to do an outstanding job supporting this mission critical customer. Winning the award over three consecutive years underscores their strong commitment to ensure superior quality in a product that lives depend on,” said Gary Fairhead, SigmaTron’s President and CEO.

SigmaTron’s Logistics Support Keeps Border Crossing Simple

When companies outsource, significant focus is placed an electronics manufacturing services (EMS) provider’s ability to manufacture superior quality products or reduce overall manufacturing cost. Less focus is placed on logistics expertise. Yet, if borders are being crossed, the EMS provider’s ability to provide efficient and timely logistics support has an impact on total cost.

SigmaTron International uses a combination of internal import/export departments within its Mexico and Asian facilities plus third party logistics and customs brokerage services to ensure that logistics and customs costs and/or duties are minimized. In-plant import/export teams electronically file all required documentation to optimize accuracy and efficiency.

SigmaTron’s team can help customers with initial product customs classifications and determine the appropriate classification to comply with regulations and minimize duties. For example, in Mexico, NAFTA is not always the best way to minimize duty liability. Mexico also has a trade agreement with the European Union (EU) and in cases where the product will be sold in Europe shipping to the EU from the factory in Mexico may offer the lowest duty cost.

SigmaTron also maintains warehouses in San Diego, CA; El Paso, TX; and Del Rio, TX to optimize the flow of materials and finished goods across the U.S.-Mexico border by having a U.S. ship to/ship from point. Raw materials are received in the U.S. facilities and shipped to factories in Mexico. Finished goods kanbans may also be located there to ensure support for variations in demand. SigmaTron’s Acuna and Tijuana, Mexico operations execute daily crossings of both materials and finished goods, ensuring rapid response to shifts in demand within the normal crossing schedule. The Chihuahua facility finds consolidating shipments represents the option best aligned with optimum cost and response to its customers’ requirements.

On the U.S.-Mexico border, goods typically cross the border in one-to-four hours and inspections of SigmaTron shipments are infrequent. In China and Vietnam, ocean containers are the preferred method of transport, although SigmaTron does arrange air shipments for customers with more time-sensitive, market-driven transit requirements. SigmaTron’s shipment volumes are large enough that ocean containers are
shipped on SigmaTron’s schedule rather than consolidated through a third party. Mutually agreed upon finished goods kanbans help minimize the need for air shipment expediting in many cases. Container shipments are occasionally pulled for inspection, but for the most part, SigmaTron has no additional delays in ocean or air container shipments due to Customs inspections.

For products manufactured offshore, logistics costs and duties, plus the opportunity costs that can come with an inefficient shipment pipeline can add up fast. In SigmaTron’s model, experts work on each customer’s behalf to ensure the best import/export and logistics strategy is executed.

Industry Pioneer Peter Sognefest Passes Away

Peter Sognefest, SigmaTron International’s Director of Operations in Vietnam and Chihuahua, Mexico, passed away in his home in Las Vegas, NV on Aug. 21. While Pete made significant contributions to SigmaTron International’s manufacturing strategy in Asia and Mexico, he was a manufacturing professional and business builder on a global scale, prior to joining SigmaTron. Over the years Pete’s companies were commercially active and did business on all continents.

“Pete was a friend to all of us as well as an asset and friend to SigmaTron. Those of us who had the privilege to work with him respected his intelligence, experience and wit. People in manufacturing today owe their livelihood to guys like Pete who helped develop the manufacturing processes and business models that made high volume electronics assembly commercially viable back when there were no industry standards to build upon. He will certainly be missed,” said Gary Fairhead, SigmaTron’s President and CEO.

Pete’s manufacturing career parallels the evolution of the electronics industry we know today. He began his manufacturing career in the early 70s with Essex Wire and Cable. Essex wanted to add electronics to support their automotive customer base. Pete led the effort to establish a circuit assembly operation in Kittanning, PA in support of the company’s semiconductor manufacturing facility near Pittsburgh. The Kittanning plant was the sole source supplier to the Ford Motor Company in 1973–1975 for the Seat Belt Interlock system, which was mandatory in all cars produced in those years.

Pete moved to Motorola in 1977 as Product Manager to lead the corporation’s efforts in electronic appliance controls. Pete was promoted to Director and later to Division Vice President of the Automotive and Industrial Group based upon the business success in appliance controls unit.

Pete left Motorola in 1984 to begin a startup company, known as Digital Appliance Controls. The business grew and DAC had manufacturing joint ventures with Daewoo in Gumi, Korea and Eastern Electronics in Taoyuan, Taiwan before establishing its own factory in Singapore in 1988.

After Emerson Electric Company’s purchase of DAC in 1991, Pete went to work as a turnaround specialist for venture capital companies and private equity firms with assignments in California and as President of XYMOX in Milwaukee, Wisconsin. Pete established manufacturing in Mexico for XYMOX and was one of the very first to open an operation in Vietnam in 1998, soon after the country was reopened for foreign investment.

Pete joined the Spitfire Controls team in 2005 under contract with his personal company, Seamoc, and opened Spitfire’s first operation in Ben Hoa City, Vietnam in 2006. Pete continued to operate the facility as Director General for the next ten years, including the last four years after the operation was purchased by Sigmatron. He also took responsibility for the facility in Chihuahua, Mexico that Spitfire Controls acquired in 2009. Under Pete’s executive leadership the factory had a 5X growth rate in the last 7 years.

Over the last decade, Pete spent 50 percent of his time in North America and 50 percent in Vietnam and Mexico. In addition to operating the two Spitfire Controls facilities, Pete served as a board member of II-VI, Inc., a semiconductor materials company with operations in Pennsylvania, China and Singapore. He also served as a board member of a Milwaukee-based metal fabrication corporation with facilities in Wisconsin and Mexico.

He received his Bachelor of Science in electrical engineering and Master of Science in electrical engineering degrees from the University of Illinois. He pursued post graduate studies in semiconductor fabrication at Carnegie Mellon University.
He also served in the United States Marine Corps Reserve.

LED Manufacturing Requires Design Through Delivery

SigmaTron International manufactures LED display boards for a variety of industries, including gaming, appliance and high power applications. The majority of its production volume applications are manufactured in its Mexico or China facilities. The Union City facility does some lower volume LED printed circuit board assembly (PCBA) manufacturing.

Achieving superior quality in LED production requires a combination of good supply chain management skills, strong focus on process control and handling during production, and strong test expertise.

“PCBA providers in general have been experiencing relatively high first pass yield infant mortality rates due to the nature of smaller LED component design and manufacturing itself. These are very delicate, wire bonded parts. Common component failures include silver-filled epoxy die attach de-bonding issues, wire bond lifting due to encapsulation around the LED die and/or the wire bonding process itself, and broken wires due PCB flexing or solder wicking stress on the wire bonds, said Yousef Heidari, SigmaTron’s, V.P. of Engineering, West Coast Operations.

Consequently, minimizing the opportunity for these defects in these parts requires a combination of close collaboration with the LED component supply chain; strong focus on design for manufacturability (DFM) and design for assembly (DFA); and very tight process controls and specialized handling during the manufacturing phase.

Selecting LED component suppliers capable of providing consistent quality parts is a key first step. Additionally, hue selection is very important. LEDs are bought by the bin. While providers are good at keeping hue consistency within a specific bin, the correct bin for the desired hue must be specified.

The delicacy and nature of LED manufacturing drives more stringent process control in PCBA manufacturing. Adhering to each LED manufacturer’s component data sheet guidelines are critical. As an example, some 0603 LEDs start out as a thin specialized printed circuit board panel containing thousands of LEDs. This large PCB panel is drilled at 2 locations at each individual LED site. These holes are plated through and will facilitate the electrical connections between the bottom mounting side and the top side where the wire bonds and/or silver die attach epoxy connections are placed. When the LED panel fabrication is completed, the panel is sawed along the hole axis. This leaves a portion of each hole present at each end of each LED or a castellated connection. The soldering must be tightly controlled otherwise hot liquid solder will flow upward into the partial hole or castellated termination and come in contact with the LED lens and attempt to dislodge it.

To address this issue, the apertures in the solder stencil use a trapezoid shape because amount of solder paste, aperture and shape of the print is critical to keep the solder from wicking up and coming in contact with the clear lens. Otherwise, the excess solder can peel off the lens or put too much strain on the wire bonds holding the lens.

The delicacy of the wire-bonded 0603 LED components also creates challenges in reflow, particularly on lead-free products. When possible, tin/lead solder is preferred because peak soldering temperatures run 217-220 degrees C. Conversely, the peak soldering temperature is 242 degrees C with lead-free solder. The temperature profile needs to be as gentle as possible to minimize the impact of peak temperatures on the wire-bonded die. The process window is very narrow. If the profile is not hot enough and long enough, the flux does not properly activate and then deactivate. If peak temperatures are held too long and when higher temperature profiles are used for lead-free solder, yields go down due to silver die attach failures. The die attach failure is normally caused by some type of force acting on the lens or due to a LED vendor wire bonding issue.

Handling following reflow is also critical. If the PCBAs are moved when hot, the LED will separate from the substrate. SigmaTron addresses this with a chiller in the reflow oven followed by a fan tray as the PCBAs exit the oven so boards are room temperature when handled. Even at room temperature, handling can be an issue. A shock or bump will break the lens of a 0603 LED.
ESD protection is also a concern.

“Ultraviolet (UV) or blue LEDs are considered the most ESD sensitive, but in reality white LEDs are also blue LEDs. A phosphor coating is used to color the lens yellow so that human eyes interpret the light as white. So basically, all LEDs are extremely ESD sensitive,” said Dennis McNamara, SigmaTron’s VP Engineering, Mexican Operations.

In SigmaTron’s process, ionizers are used in all areas where LED PCBAs are handled in addition to the factory’s standard ESD protective flooring and employee protective clothing.

In addition, to the DFM and process considerations, 0603 LEDs also have design for assembly (DFA) considerations. If a plastic light guide or light focusing device is placed too near the 0603 lens, shock and vibration in normal use can cause the device to touch the lens and cause it to break.

Larger package LED components do not have this level of fragility. Higher power LED lighting may use an aluminum PCB for faster heat dissipation. In some cases, areas of the PCB may have areas where the dielectric insulative material has removed from the ground pad. This drives a need for greater attention to solder paste disposition accuracy.

The Acuna, Mexico facility still occasionally runs through-hole LEDs in low volume for legacy products. DFM and adherence to IPC design guidelines is important with these PCBAs, as the hole sizes for leads and the spacing between the holes is critical. If spacing between holes is too far apart or too close together, it will place stress on the leads and weaken the part. Through-hole LEDs should also be inserted with a standoff.

LEDs PCBAs are typically tested using in-circuit test (ICT). However, standard ICT will not test for brightness. At SigmaTron this is done using cameras and software that analyzes pixel values. The alternative test option measures LED hue using a spectrophotometer with an integrating sphere, which requires precise distance between the LED and test equipment. From a cost and test time perspective, the latter method was deemed too costly when the two methods were analyzed in terms of cost and accuracy. In SigmaTron’s method, for white LEDs, the ratio of blue pixel intensity to red pixel intensity is measured to verify the correct hue.

“With careful planning LED manufacturing can generate high yields. However, the margin for error in process or handling is much smaller for packages such as the 0603 SMT device. Our goal is minimize the potential for these errors to occur,” added Dennis.

Suzhou Facility’s Systems Provide Superior Support for Medical Customers

Now that SigmaTron International’s Suzhou, PRC has achieved ISO 13485 certification, medical projects are being added. However, the foundation for supporting programs with requirements for superior quality and traceability practices was in place long before certification was pursued. As with all SigmaTron facilities, the Suzhou facility has long been focused on a strong systems strategy. This “paperless” factory approach cost effectively addresses traceability requirements for a range of industries, plus provides real-time project status 24/7. In addition, because these systems are designed to minimize manual transactions that can lead to production errors, there is a defect mitigation aspect, as well.

SigmaTron uses a combination of proprietary and internally-developed systems for enterprise and shop floor management. All facilities utilize a common ERP system plus Agile Product Lifecycle Management (PLM) tools. The Suzhou team has actually been a leader in enhancing traceability and shop floor control, developing a Manufacturing Execution System (MES) system known as Tango to address that in 2013. SigmaTron’s IT department takes a distributed approach to continuous improvement in its systems by letting teams at individual manufacturing facilities identify specific gaps in shared systems and develop appropriate software tools. These solutions are then tested at the facility that identified the need and later transferred across all facilities. In this case, Tango was deployed to other facilities beginning in 2014.

Tango use starts in incoming inspection. When the bill of materials (BOM) is originally entered in Tango, all special instructions are entered as well. This ensures that handling and storage instructions are always associated with each part in the system. As material is received, the system also creates an internal log number which lists purchase order number, date code and lot code. This supports not only device history recordkeeping during manufacturing, but also a first in, first out (FIFO) system during kit preparation. The system has also helped free up warehouse space since it tracks lot code and warehouse bin location. As a result, material can be stored in the warehouse solely based on optimum space utilization. When the part is needed, the system directs the stock person to the appropriate bin location. As material is pulled or counted, the system tracks the information.

Tango also assists with point-of-use stocking activities. For example, in Suzhou, low value, high usage small parts such as resistors, capacitors, etc. are stocked at point-of-use rather than kitted. When a bin is emptied, the production operator scans a Tango card and that triggers a pull signal in the stockroom.

Tango also does reel/feeder verification. When production operators load a reel, they scan both the reel and the feeder. The system verifies that reel is correct for that feeder number and that the feeder is loaded into the correct slot in the feeder table.
A strong system strategy also drives documentation creation and control, and work order scheduling and tracking.

Product documentation is transferred electronically from customers, eliminating potential errors associated with more manual processes. Electronic work instructions are displayed on monitors at each workstation. These work instructions include video showing the steps necessary to perform the designated operation, ensuring that operators have clear examples of the optimum way to perform specific tasks. Product is bar coded and tracked through each operation using the Company’s proprietary iScore system. Real-time production status monitors display data in each work area, and customers can access production status remotely via the Score portal. The end result is a production environment where all workers have access to real-time production metrics and bottlenecks or quality issues become immediately apparent.

SigmaTron’s strong systems strategy combined with standardized key processes seamlessly support multi-facility builds. The Suzhou facility’s recent addition of ISO 13485, adds a superior quality Asian location option for companies pursuing a regionally-focused outsourcing strategy.