Printed-circuit boards (PCBs), no matter what brand or type, come attached with one inescapable reality—they are inherently failure-prone. Planning for when, rather than if, your circuit boards will malfunction thus becomes the optimal approach, as it leads to reduced costs and helps avoid future headaches.
Shipping out your faulty PCB assembly (PCBA) for service can be stressful when the production schedule is tight and board failure has already caused downtime. It pays, then, to have practiced technicians discover the root cause of a circuit board’s failure and analyze the extent of its damage.
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In addition to physical damage to the circuit card, like cracks and corrosion, discrete and power components can deteriorate for a wide range of reasons, such as extreme heat, over/undervoltage surges and sags, and age. Also, contaminants like grime and dust frequently induce trace damage. Contacting a repair provider is the best way to ensure that your circuit-board assembly functions properly once it’s reinstalled and, more importantly, that your industrial electronics won’t fail again a few weeks down the road.
Even though factories save millions every year by repairing and/or reworking circuit boards, the guesswork associated with choosing a repair shop and anxiety about its quality of craftsmanship convince many plant managers to instead purchase brand new replacement boards. This decision ultimately turns costly in the short and long term. In addition to spending an arm and a leg for new boards, OEMs don’t provide preventive and corrective repair recommendations and actions to help your electronics equipment (not just the circuit-board replacement part) exceed performance expectations.
What criteria should guide your selection of a service provider for circuit-board repair or rework? We recommend focusing on “three E’s”: expertise, equipment, and economies of scale.
Circuit-board repair remains a labor-intensive process at its core, demanding highly skilled handiwork and technical knowledge.
One benefit of working with a service-centric repair company, instead of an OEM, is that its profitability depends on the capabilities and customer service of its engineers and technicians. Its ability (or inability) to deliver high-quality and reliable repairs before deadline, especially when large or complex projects are on the line, powers (or stunts) the company’s growth.
Subsequently, longevity should be given strong consideration when choosing a repair company. There’s a reason why some repair providers have been operating and growing for several decades and others stagnate after a few years in business.
Another obvious factor to bear in mind is what certifications are attached to the firm. If a company’s technicians aren’t qualified in electrostatic-discharge (ESD) and Institute for Interconnecting and Packaging Electronic Circuits (IPC) repair and rework standards, you shouldn’t trust them to handle advanced microprocessors and digital signal processor circuits.
On a similar note, while not advertised publicly, ongoing specialized training for technicians is a sign of a competent independent service provider (ISP) committed to competing on a global stage. Technicians should be able to operate the latest diagnostic technology and develop world-class programs for handling and testing parts.
Beyond the ability to quickly diagnose a failing circuit-board component, execute its repair, test its performance, and provide an aggressive warranty, repair companies should also be eager to offer value-added technical services. These might include removing and replacing stressed parts; improving inefficient design with stronger, more reliable technology; remanufacturing unsalvageable or obsolete components; manufacturing custom-designed products; and implementing end-of-life (EOL) strategies.
With everything else held equal, up-to-date diagnostic and testing instruments can make the difference between a one-day and three-day turnaround on an urgent project. For this reason alone, ISPs invest millions to equip their facilities with the most state-of-the-art equipment available.
Specifically, ISPs need a mix of equipment to address the digital, analog, and power sections of circuit cards. A properly outfitted PCB repair facility will incorporate the following equipment into its production process:
• In-circuit testers perform both a powered, in-circuit logical test of digital and many analog ICs, as well as signature analysis. These tests check for the Boolean functions from digital chips and provide a signature analysis of dynamic operation. Unknown chips can be identified by their Boolean output. One in-circuit tester, the Diagnosys PinPoint System, includes libraries of digital chip pinouts to assist the technician in troubleshooting. It also can determine the wiring patterns of the circuits.
• Data I/O programmers read, verify, and store data in programmable logic devices, such as programmable read-only memories (PROMs), microprocessors, and memory devices. A master database stores all programmable devices for current and future repairs.
• Hot-air IC installation and removal systems subject surface-mount ICs to temperature-controlled hot air to reflow solder. A vacuum pickup tool removes or installs the chip with the help of a magnifying charge-coupled device (CCD) camera.
• Signature analysis is the primary diagnostic tool for PCB repair activity. It applies a current-limited ac signal across two points of a semiconductor junction. The current flow causes a vertical deflection of the cathode-ray-tube (CRT) trace, while the applied voltage causes a horizontal deflection. Together, they form a unique impedance (V-I) signature that represents the overall health of the junction under test. Analyzing the deflection signature reveals whether the component is good, bad, or marginal. Many units also can internally fire gate-triggered devices while viewing the V-I curves.
• Oscilloscopes, either analog or digital, analyze voltage waveforms under power.
• Function generators simulate square, sinusoidal, or triangle wave input and trigger signals.
• Digital voltmeters (DVMs), ranging from 3.5- to 6.5-digit meters, measure voltages down to 6.5-digit precision at the selected measurement range
• Cap and inductance meters, developed by Sencore, analyze capacitors for capacitance, equivalent series resistance (ESR), dielectric leakage, and frequency response. Inductance meters specifically measure similar attributes in coils.
• Power-supply load boxes are dynamic load banks for testing power-supply capacities, hold-up time, and spike sensitivity.
• Calibrators are reference systems traceable back to National Institute of Standards and Technology (NIST) standards for final adjustment of temperature, flow, and pressure related products.
• Mings, which are handheld testers, identify and check various ICs.
• System or simulation testers provide a means to test assemblies from the connectors to determine entire functionality.
Furthermore, all equipment should be identified as either “used for diagnostic work” or “for final repair” (calibrated). All calibrated equipment should be on a scheduled gauge program.
Economies of Scale
The best repair, rework, and overhaul options at the lowest price points are only sustainable with a highly scalable ISP. For example, larger repair shops can offer more agility by leveraging their inventory of new and refurbished circuit-board assembly parts. This is especially important as it relates to emergency/rush repair services when customers experience production downtime.
In addition to cost-effectively replacing defective circuit-board components with new and/or more reliable parts, plant managers, owners, and operators want a full-service partner that can improve equipment performance and overall operating efficiency. Most repair shops, however, do not have the manpower, experience, or technology necessary to provide value-added PCB redesign and manufacturing services. In particular, for small and medium-sized ISPs, it’s simply cost-prohibitive.
When your circuit-board repair project is complete, the remanufactured, like-new-condition board(s) should always meet the same industry performance specifications as new PCBs. If you found a quality shop, you should expect that the parts will easily exceed the expected lifetime of the original board. When all is said and done, choosing the right ISP can save you up to 70% versus the cost of buying replacement PCBs from the OEM.
Ron Fukui is the director of engineering and technology for the Repair Services Division at PSI Repair Services Inc. He has a BS in electrical engineering technology from California Polytechnic University. Also, he has been an active member of the South East Michigan Community Alliance (SEMCA), where he was a member of the board of directors from 1996 to 2001. He was a member of the Board of Directors for Michigan’s School-to-Work programs from 1994 to 1998 as well. For more information about PSI Repair’s circuit board assembly repair services, call 800-325-4774 or visit http://www.psi-repair.com/repair-services/printed-circuit-board-repair.