Zulki’s PCB Nuggets: DOEs on Call for New Wearable Medical Devices

Medical electronics continue to make even greater technological advances with recent R&D developments and promise to take on new forms. Biosensors for human-machine interfaces (HMIs) and new, flexible electrodes are leading the way. They are among the most recent developments and promise more sophisticated medical wearable devices for health monitoring.

Here, biosensing refers to devices that touch the human body. The idea is to collect a great deal of information from our bodies so that medical personnel can get a better understanding of our health conditions and wellbeing. According to researchers, human saliva and sweat are excellent candidates for biosensors to capture a wealth of human health data. Medical personnel can check out certain characteristics of a human’s sweat to gauge that person’s chemical excess or deficiency.

Keep in mind that medical wearable devices are already small and thin. But this next round is designed with wearable skin-like electrodes, which are so thin that they are measured in microns and nanometers rather than in mils and inches. Moreover, these new electrodes are not rigid and gold-coated like traditional ones. Those are difficult to insert inside the body. Instead, they’re flexible, smaller in size, and nimble so that they can easily go into different parts of the body.

Medical wearable devices are getting smaller and thinner, but on the other hand, they have considerable intelligence thanks to the embedded biosensors in certain innovative formats. With the onset of these technological advancements, our industry is showing signs of a rapid transformation in the healthcare sector.

For example, some of that transformation stems from hydrogel-associated electronics research by MIT engineers. There are others beyond that serving as the foundation for flexible wearable products. One such device in that category is the piezoelectric sensor. It’s more commonly known as a piezo sensor and uses the piezoelectric effect to measure changes in pressure, acceleration, temperature, strain, or force by converting them to an electrical charge.

The flexible and stretchable circuit devices we’re talking about here are based on newly created materials that have some of the similar functionalities that human skin has. These devices can be worn for a lengthy time period for continuous and persistent HMI. Some have a conformal coating on the sensor that touches the human body most of the time to measure the biopotential at all times.

The use of gold-coated electrode metals and probes or a type of conductive gel or epoxy is the traditional way to check out different signals. But there are issues with that; specifically, the conductive gel dries out in a given period of time. This causes not only signal degradation over time, but the signal-to-noise ratio (SNR) also deteriorates.

These issues can result in small change in any human condition without giving the intended results. Sometimes, as these gels dry out and electrodes are left with inaccurate signals, the result is an inaccurate reading of human body signals and conditions; thereby, doctors cannot correctly diagnose these conditions.

DOEs Pick Up the Ball

Medical electronics advances and issues like these introduce perplexing, head-scratching, and difficult PCB assembly and manufacturing issues because they pose a great number of questions. At this stage, the role of design for experiments (DOEs) steps into the spotlight to pick up the ball.

A DOE is defined as a design of information-gathering experiment where variation is its main characteristic. It can be performed as a fully or partially controlled set of experiments. Controlled experiments involve changing one variable and keeping everything the same. DOEs are in the domain of the EMS provider or contract manufacturer (CM).

They have, or should have, the necessary experience to work hand in hand with medical equipment OEMs. Working together means investigating and deciding on a logical roadmap for assembling and manufacturing these advanced medical wearable devices based on biosensors and flexible, stretchable electrodes.

The objective of a DOE is to collect as much information as possible in terms of doing the same experiment in different ways to achieve the medical electronics OEM’s objective. Experimental designs can be used at the point of greatest leverage to reduce manufacturing complexity and introduce new technology.

When the prototype is being designed and manufactured, there is some uncertainty about how the design would work. Therefore, speeding up the process can reduce time to verify product functionality and time to market. This reduces the design chain cycle, product material, and labor complexity.

How to Effectively Conduct DOEs

In short, you need to know what you are doing and talking about when it comes to a DOE. Here’s what the OEM expects from the EMS provider or contract manufacturing when a DOE is handed over:

  • Nature of existing problems stated
  • Availability of common solutions
  • Brainstorming for out of the ordinary solutions
  • Ongoing controlled experiments, changing one variable at a time
  • Repeating these controlled experiments using other variables
  • Arriving at a desirable or semi-desirable result

To comply with those OEM requirements, the EMS provider must have extensive and detailed experience in PCB design/layout, fabrication, and assembly/manufacturing, including microelectronics.

Beyond those requirements, the management must be innovative and forward-thinking. In some cases, DOEs demand improvising, and in most instances, the success in improvising comes about due to experience. Factors involved, with either controlled or uncontrolled variables, come from personnel experience. Successful DOEs also take into account the willingness of an EMS provider to invest in experiments of its own at their own expense and time to figure out an OEM solution to a particular and troubling issue.

Zulki Khan is the president and founder of NexLogic Technologies Inc.

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2020

Zulki’s PCB Nuggets: DOEs on Call for New Wearable Medical Devices

08-05-2020

Zulki Khan explores how biosensors for human-machine interfaces (HMIs) and new, flexible electrodes are leading the way, are among the most recent developments and promise more sophisticated medical wearable devices for health monitoring.

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Zulki’s PCB Nuggets: Soft Electronics Pose PCB Microelectronics Assembly Challenges

07-08-2020

Zulki Khan explains how PCBs have moved from traditional large rigid boards to considerably smaller rigid and combinations of rigid and flex circuit boards, even to the point that bare chips and wire bonding are used during the PCB microelectronics assembly of these tiny boards.

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Zulki’s PCB Nuggets: Medical Miniaturization and PCB Microelectronics Assembly

06-24-2020

Medical electronics continue to be a gamechanger, with miniaturization being foremost today in the minds of medical OEMs. Zulki Khan discusses how there is a growing demand for even greater device and component miniaturization that plays a major role in the PCB microelectronics assembly of these medical devices today.

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Zulki’s PCB Nuggets: Add Hi-rel to ISO 13485 for More Robust Ventilator PCBs

05-13-2020

It's important to meet FDA and ISO 13485 standard quality and reliability requirements for ventilators and other medical equipment. Zulki Khan explains how there’s still more that ventilator OEMs need to put into practice, specifically in the high-reliability or “high-rel” area to further add to ISO 13485.

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Zulki’s PCB Nuggets: Urgent Call for Ventilators—PCB Technology at the Ready

04-15-2020

An urgent call is out to medical equipment makers that thousands—even millions—of ventilators are in the greatest demand in our history due to the worldwide COVID-19 outbreak. Zulki Khan explains how new ventilator makers—as well as traditional ones—must weigh a number of key PCB design, assembly, and manufacturing factors.

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Zulki’s PCB Nuggets: Putting the Heat on for Thermal Profiling

03-11-2020

A unique thermal profile is designed for each PCB job undergoing conventional SMT assembly, as virtually every PCB assembly professional knows. But what about a PCB assembly project involving both conventional rigid board and an extraordinarily small rigid or rigid-flex circuit undergoing microelectronics assembly? Zulki Khan covers PCB hybrid assembly, which requires two separate, unique, and distinctly different thermal profiles.

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Zulki’s PCB Nuggets: 7 Steps to Successful Assembly for Medical Devices Using Microelectronics

02-12-2020

Seven major steps need to be taken to achieve successful SMT and microelectronics assembly for medical electronic devices. Zulki Khan explains how these key steps take on special significance for newly emerging implantable and ingestible medical devices and result in medical devices that are robust, smaller, highly reliable, more powerful, and lighter.

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Zulki’s PCB Nuggets: Successful PCB Microelectronics Assembly

01-15-2020

In addition to coverage of PCB microelectronics subjects, Zulki Khan addresses one of the most crucial areas: PCB fabrication that creates the circuit board undergoing microelectronics assembly. The burning question is, “Why is fabrication vitally important when it comes to successful microelectronics assembly?”

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2019

Zulki’s PCB Nuggets: Vital Details for Implantable Medical Devices

12-04-2019

In addition to smart pills and smart cameras, which Zulki Khan covered in a previous column, another segment of the medical electronics devices market is rapidly growing, as well: implantable medical devices, which medical personnel surgically or otherwise insert into various parts of the human body. Zulki explains the extra measures required for these devices.

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Zulki's PCB Nuggets: Multi-tier Wire Bonding—Diving Into PCB Microelectronics

11-07-2019

As the name implies, multi-tier wire bonding involves several levels of wire bonding beyond the single level of wire bonding, which is traditionally used in semiconductor and/or PCB microelectronics assembly. Here, you have two, three, and four levels of wire bonding, in some cases, called stacked wire bonding. Also, multi-tier wire bonding offers OEMs a solution when the number of inputs/outputs (I/Os) are far beyond the traditional ones that are used in the single wire-bonding application.

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Zulki’s PCB Nuggets: Smart Pills & Cameras—The Next Frontier for PCB Microelectronics

10-23-2019

"Take two aspirin and call me in the morning," is the proverbial, jovial, and often-cited elixir that doctors have prescribed over the years for whatever ails you. Today, medical electronics are adopting the same concept but with new technologies. Now, the phrase, "Take two aspirin," takes on new meaning, as medical electronics move into new frontiers of inspecting a human’s gastrointestinal tract with new, revolutionary ingestible smart pills and "pill cams."

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Zulki's PCB Nuggets: A Better Grasp of Glob Top Epoxy Factors

09-25-2019

In my last column, I cited important aspects of glob top epoxies, calling attention to the fact there are different epoxy manufacturers. In this column, I will continue to emphasize six other important factors of glob top epoxies.

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Zulki’s PCB Nuggets: Get a Handle on Glob Top Epoxies

09-12-2019

Most often, glob top is the prevalent method EMS providers use today. However, the most important point to be made about glob top is the fact that multiple manufacturers are producing different glob top epoxies. And within each manufacturer, there are numerous types of epoxies being produced. Another key point is that EMS providers and contract manufacturers generally are the ones deciding on the kind of epoxy to use. This column will further describe how you can get a handle on glob top epoxies.

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Zulki’s PCB Nuggets: Protect the Die and Wire Bonding for Effective PCB Microelectronics Assembly

07-31-2019

Protecting bare dies on a PCB or substrate is a major process of microelectronics assembly. As we’ve said before, microelectronics assembly and manufacturing work in tandem with traditional SMT manufacturing for complete PCB hybrid manufacturing of today’s smaller form factor products, including IoT, wearables, and portable devices.

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Zulki’s PCB Nuggets: PCB Microelectronics—Inspection and Calibration

07-18-2019

Microelectronics manufacturing is the companion of SMT manufacturing and forms PCB hybrid manufacturing. Tools for SMT manufacturing have been around for a long time and have proven their value. Now, with microelectronics, new and different types of high-powered laser microscopes are populating the microelectronics assembly and manufacturing area to provide highly effective inspection and calibration.

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Zulki’s PCB Nuggets: Three Die Attach Methods for Microelectronics Manufacturing

06-27-2019

Die attach technology is increasingly being applied in PCB hybrid manufacturing (i.e., combining traditional SMT manufacturing with microelectronics) to comply with the requirements of small PCBs, especially rigid, flex, and combination rigid-flex circuit boards. These smaller boards are used in a variety of IoT, wearable, and portable applications.

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Zulki’s PCB Nuggets: Consider the Integrity of Wire Bonding

06-12-2019

While reliability and integrity can be regarded as synonymous as far as PCB manufacturing with microelectronics assemblies is concerned, the integrity of wire bonding—the methodology of interconnecting the wire to the bond pad—takes on other reliability-associated process qualities. Here are three factors that need to be implemented to create the integrity of wire bonding.

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Zulki’s PCB Nuggets: Avoid PCB Wire-bond Loop Failures

05-30-2019

Today, hybrid PCB manufacturing is making greater inroads into our industry, which is the marriage of traditional SMT manufacturing together with microelectronics and wire bonding. In many cases, the OEM working with EMS providers doesn’t fully understand the nuances of effective wire bonding and related failures.

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2014

Tighter Scrutiny Needed for PCB Cleaning Agents

05-13-2014

PCB cleanliness on the assembly floor is now getting more attention, due to tiny residues and contaminants being left on assemblies after new, advanced assembly processes. Cleaning methodologies, testing, analysis, and special chemistries are being taken to a new level to assure customers of ultraclean boards to avoid costly latent issues.

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Zulki's PCB Nuggets: Tighter Scrutiny Needed for PCB Cleaning Agents

05-13-2014

PCB cleanliness on the assembly floor is now getting more attention, due to tiny residues and contaminants being left on assemblies after new, advanced assembly processes. Cleaning methodologies, testing, analysis, and special chemistries are being taken to a new level to assure customers of ultraclean boards to avoid costly latent issues.

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Uncovering Assembly Problems of High-Speed PCBs

03-12-2014

The high-speed board may be perfect when it comes to BGA assembly. All the balls properly collapse; all the thermal profiles are accurately determined and performed. All soak temperatures, pre-heat, soak, and cool-off periods fall within manufacturer limits and ranges. Yet, this high-speed board fails at high speed at the time of system functional level testing in the system.

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Zulki's PCB Nuggets: Uncovering Assembly Problems of High-Speed PCBs

03-12-2014

The high-speed board may be perfect when it comes to BGA assembly. All the balls properly collapse; all the thermal profiles are accurately determined and performed. All soak temperatures, pre-heat, soak, and cool-off periods fall within manufacturer limits and ranges. Yet, this high-speed board fails at high speed at the time of system functional level testing in the system.

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EMS Discovers Mature IC Technologies

01-14-2014

Columnist Zulki Khan asks, "Did you know that really new, up-to-the-moment PCB technologies are nesting on the doorstep of PCB assemblers?" In fact, he says some of these technologies are very mature, but they're completely new to the assembly side of things.

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Zulki's PCB Nuggets: EMS Discovers Mature IC Technologies

01-14-2014

Columnist Zulki Khan asks, "Did you know that really new, up-to-the-moment PCB technologies are nesting on the doorstep of PCB assemblers?" In fact, he says some of these technologies are very mature, but they're completely new to the assembly side of things.

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2013

Another Look at AOI

11-13-2013

PCB inspection is taking on greater significance as boards and packaging become increasingly smaller, with greater functionality. Automated optical inspection (AOI) and its backup associate, X-ray, team up to catch a variety of board assembly problems. But it's AOI that's at the forefront of this process.

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Zulki's PCB Nuggets: Another Look at AOI

11-13-2013

PCB inspection is taking on greater significance as boards and packaging become increasingly smaller, with greater functionality. Automated optical inspection (AOI) and its backup associate, X-ray, team up to catch a variety of board assembly problems. But it's AOI that's at the forefront of this process.

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Zulki's PCB Nuggets: ECOs Reviewed - The Importance of Accuracy

09-11-2013

Designers can perfectly layout a design and, in theory, follow written specifications to the letter, but when one factors in the practicality of that design, virtually everything associated with it has its limitations--ranging from the material used to make the board to assembly, machine tolerances, and process limitations.

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