printedcircuitboards Archives - VEXOS https://www.vexos.com/tag/printedcircuitboards/ Local Service. Global Capabilities. Sat, 11 Nov 2023 00:00:21 +0000 en-CA hourly 1 https://wordpress.org/?v=6.8.1 https://www.vexos.com/wp-content/uploads/2021/03/favicon.png printedcircuitboards Archives - VEXOS https://www.vexos.com/tag/printedcircuitboards/ 32 32 VEXOS featured in Manufacturing in Focus Magazine https://www.vexos.com/2023/03/16/vexos-featured-in-manufacturing-in-focus-magazine/ Thu, 16 Mar 2023 19:30:21 +0000 https://vexos.com/?p=992744 We are elated to be featured in the March issue of Manufacturing In Focus. Thank you for covering Vexos and highlighting our state-of-the-art manufacturing facilities and capabilities. Check out page 35 of the current issue OR follow the post on LinkedIn to read more about Vexos.

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We are elated to be featured in the March issue of Manufacturing In Focus. Thank you for covering Vexos and highlighting our state-of-the-art manufacturing facilities and capabilities.

Check out page 35 of the current issue OR follow the post on LinkedIn to read more about Vexos.

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Understand the Total Cost of Your Printed Circuit Board Ownership https://www.vexos.com/2022/07/20/understand-total-cost-of-your-printed-circuit-board-ownership/ https://www.vexos.com/2022/07/20/understand-total-cost-of-your-printed-circuit-board-ownership/#respond Wed, 20 Jul 2022 12:00:00 +0000 https://vexos.com.superdorx.com/?p=989786 Electronics manufacturing services (EMS) suppliers are vital for maintaining efficient electronic production lines, but the costs and values of such EMS suppliers can be easily misunderstood. For example, changing a printed-circuit-board (PCB) supplier can be more costly than expected if all the cost drivers and potential savings are not at least somewhat understood. By identifying…

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Electronics manufacturing services (EMS) suppliers are vital for maintaining efficient electronic production lines, but the costs and values of such EMS suppliers can be easily misunderstood. For example, changing a printed-circuit-board (PCB) supplier can be more costly than expected if all the cost drivers and potential savings are not at least somewhat understood. By identifying the associated cost drivers with manufacturing PCBs, it is possible to develop a total cost of ownership (TCO) model and a more straightforward approach to capturing real savings opportunities when building the next batch of PCBs.

Many factors are involved in understanding the cost of building different PCBs. In studying the different variables and costs in manufacturing PCBs, it was possible to develop a list of 10 cost drivers that, when properly understood, can be used to reduce the costs of manufacturing PCBs. While this is not an all-inclusive list, it does cover a significant amount of the key elements that need to be taken into consideration when a PCB is being manufactured:

10 PCB manufacturing costs

  1. The number of layers.
  2. The size of the PCB.
  3. The panel utilization (percent) per number of PCBs on a working panel, where a standard working panel is 18 x 24-in.
  4. The number of holes.
  5. The trace width/spacing.
  6. The surface finish/solder mask finish of the PCB.
  7. The choice of base laminate/thickness of the PCB.
  8. The copper weight/thickness used on the PCB.
  9. The routing or die punching of the PCB profile.
  10. The labor costs and amount of batch process steps needed to produce the PCBs.

Some of these cost drivers are straightforward, such as the size of the PCB (where cost rises with increased size) and the number of layers, where more complex circuits require more PCB layers, but this also means increased cost. Panel utilization refers to the number of arrays or PCBs per array that can be produced on a working panel. This is typically calculated by the percentage of utilization, which is calculated from the total area for the PCB divided by the total panel area based on a typical 18 x 24-in. working panel. Higher panel utilization percentages mean lower overall costs. Utilization above 75 percent is considered good.

Another cost driver of PCB costs is the number of holes and variety of hole dimensions. Depending on the number of sizes and quantities, each different hole diameter equates to longer machining time, and more use of drill bits, resulting in increased costs. If hole sizes become extremely small, whereby laser drilling may be necessary, this will also add significant costs to manufacturing a PCB.

PCB manufacturing costs are also impacted by trace widths and trace spacing: the width of the individual traces and how close they are to each other from a trace edge to trace edge can impact the cost, based on the cost of the imaging/plating equipment and process capabilities of a PCB manufacturing facility. Tighter, finer trace widths result in increased PCB production costs.

The type of surface finish on a PCB will also impact manufacturing costs and the manufacturing process method used to produce the boards. Typically, lead-free hot air solder leveling (HASL) is the lowest-cost alternative (not good for fine pitch SMT), followed by immersion tin, immersion silver, organic solder preservative (OSP) (shortest shelf life), flash gold, immersion gold, and thick gold. Several alternative finishes are available, each with advantages and disadvantages that should be investigated before deciding on a particular surface finish.

The base laminate that is specified for a PCB production job can also impact costs. It is better to specify material characteristics that are required than to specify a specific manufacturer’s laminate. An alternate approach is to add “or equivalent” to a specific manufacturer’s material. Allowing the PCB manufacturer to use commonly used materials not only produces the lowest possible cost but can also reduce lead times.


Increases in copper weight and thickness in a PCB generally mean increases in cost. The copper in a PCB is rated in ounces and represents the thickness of 1 oz. of copper rolled out to an area of one square foot. For example, a PCB that uses 1 oz. copper has a thickness of 1.4 mils. A PCB that uses 2 oz. copper has a thickness of 2.8 mils. The base copper thickness used, or how much the product is going to be plated to meet the required thickness, will impact the cost of the PCB. Typically, the lowest cost option is 0.5 oz. copper (thickness of 0.7 mils), increasing in 1-oz. increments to 9-oz. copper. PCBs usually fall in the 1 to 2 oz. range.

The costs of routing or die punching a PCB profile can vary since there are different methods for removing laminate material when developing a PCB’s profile. The main approaches are based on routing, using a high-speed routing bit cutter to remove the laminate materials when creating a PCB profile. The other method is producing a punch that removes the laminate during the punch process. Typically, the punch process is a lower-cost option, but it will have some additional tooling costs to develop the punch tool.

Last on the list of 10 PCB manufacturing costs is the cost of labor, which can be significant when producing PCBs. Most circuit-board-assembly facilities incorporate a batch processing manufacturing process, which will require significant handling for each of the individual processes and moving a product from process to process. When performed at manufacturing locations with lower labor costs, the unit labor costs for the PCBs will usually be less. Other factors that can impact PCB manufacturing costs include whether the board is to be produced to the level of a particular standard, such as an IPC Class 2 standard, which is generally applied to standard electronics, or IPC Class 3, which is more stringent and more expensive. This is not the ultimate list of cost drivers for manufacturing PCBs but understanding how these 10 items can affect costs can pave the way for a better understanding of how to control PCB manufacturing costs.

For more information on the Total Cost of Ownership Contact VEXOS today!

Operating in several locations across North America and Asia, VEXOS is a high-mix, high complexity, mid to low electronics manufacturing and custom material solutions provider with a proven track record of delivering high quality, custom-designed electronics manufacturing services, and supply chain solutions to a diverse group of OEMs. Vexos’ early involvement in the design cycle can provide customers with a more cost-effective product that has increased manufacturability, quality, and reliability throughout its entire lifecycle. During their involvement in design reviews, they focus on key areas throughout the cycle and provide critical feedback to address potential issues and ensure a successful new product introduction. Design reviews can also be categorized by material (Design for Supply Chain), test (Design for Testability), PCB fabrication (Design for Fabrication), assembly (Design for Assembly), and manufacturing (Design for Manufacturing).

VEXOS prides itself in working closely with its prospective and current customers to ensure that they offer value that far exceeds the six fundamental cost drivers of a supplier-customer relationship.

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A Look at Medical Electronics Design and Assembly Challenges https://www.vexos.com/2019/01/31/a-look-at-medical-electronics-design-and-assembly-challenges/ https://www.vexos.com/2019/01/31/a-look-at-medical-electronics-design-and-assembly-challenges/#respond Thu, 31 Jan 2019 13:47:00 +0000 https://vexos.com.superdorx.com/?p=989684 We recently spoke with Dr. Despina Moschou, lecturer at the University of Bath, as well as Kaspars Fricbergs, VP of global quality, and Tom Reilly, director of marketing and sales operations, of EMS firm Vexos Corp., to learn more about the challenges and opportunities in medical electronics design and assembly, as well as the relevant…

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We recently spoke with Dr. Despina Moschou, lecturer at the University of Bath, as well as Kaspars Fricbergs, VP of global quality, and Tom Reilly, director of marketing and sales operations, of EMS firm Vexos Corp., to learn more about the challenges and opportunities in medical electronics design and assembly, as well as the relevant regulatory and supply chain issues.

Stephen Las Marias: Tell us more about yourself, Despina, and your lab-on-a-chip project.

Dr. Despina Moschou: I always start by introducing people to what lab-on-a-chip is in general. Lab-on-a-chip is not my invention—I have to be very clear on that. Professor George Whitesides from Harvard and Professor Andreas Manz first suggested it. They came up with this idea in the mid-1990s. The concept was miniaturizing a complete biomedical laboratory in a microchip. This vision is what we, the scientific community all over the world, have been trying to do for the past 20–30 years.

Before I became involved in this field, my original background was purely electronics. I’m an electronics engineer, I graduated from Athens, and I have a Ph.D. in microelectronics. During my first post-doctoral research, I ran into the field of lab-on-a-chip—in particular, microfluidic devices. Since then, I have been involved in that because the impact of this technology is enormous once it reaches everyday life.

What does this technology do? Imagine if you could have the whole biochemical laboratory on your hand. Wouldn’t that be cool? And apart from being cool, let’s assume we have a biomedical laboratory such as a health-care facility. What do you do when you want to identify a diagnosis? Either you or your doctor will take a sample—such as blood, urine, or any other kind of biological sample—and will take a bottle of it and ship it to a laboratory. The laboratory will do an analysis. It will take a few hours, days, or even weeks, and then you will receive the results. This is the current routine in health-care practice for all kinds of diseases, whether infectious, routine checking, or monitoring your pregnancy or cancer treatment. Wouldn’t it be great if we could avoid all the delays? How different would it be if instead of taking things to the laboratory, we could bring the laboratory to the people who need it.

And because you don’t have to delay, treatment can start immediately. You wouldn’t have to wait. Starting treatment is extremely important for overcoming any kind of disease. It will also have a huge impact in environments and countries where you don’t have access to health-care facilities whatsoever, such as remote islands or low- and middle-income countries where you don’t have access to health-care facilities with laboratories. In all of these cases, having a miniaturized laboratory can make a huge difference. This is roughly the vision of what we are trying to realize with our Research at the University of Bath.

Barry Matties: The technology itself is really interesting because they’re using these miniature micro-pumps to move fluid around, and the idea was to actually incorporate it into the build of the circuit board. And it’s really a game-changer. What’s interesting about this also is it’s one and done, meaning you use it, you throw it away and you buy more. So, from a consumption point of view, millions and millions of units will be sold. And you’ve already had success in creating the lab onboard and doing diagnostics, correct?

Moschou: Yes, we have.

Matties: This really goes with the continued desire for smaller, faster electronics, more affordable, and it’s going to revolutionize the way that medical diagnostics is done.

Moschou: Exactly. What I have been driving for the past few years is trying to implement Lab-on-Chip technology on PCBs. At the moment, and ever since the invention of lab-on-a-chip, every research laboratory in the world has been using their own in-house technique to fabricate those devices. We don’t have lab-on-a-chip technology with one way to manufacture things. In electronics, we have PCBs. We have the standard card that we all use to simulate and design boards, and manufacturers globally that have standardized procedures because this is an industry that’s been around for many years.

In lab-on-a-chip, this is not the case. We are still at the research stage and are gradually transitioning into actual commercialization of devices the past few years. One of the problems delaying this process is that we don’t have factories. We don’t have a lab-on-a-chip factory where I can make something in my lab, design it, and then I can go and get millions of them. This is why I have been trying and persisting on the lab-on-PCB approach because we can actually use the factories that are out there right now fabricating electronic boards and transition into something more advanced—something smaller and more intelligent that can add further functionality to the electronic boards. This time, we can incorporate miniaturized channels to transport the liquids and the fluids that we want to analyze, which are called microfluidic tunnels. We can have analytical biomedical devices on a PCB.

This is not conceptual. I have been presenting for the past few years on the projects and prototypes we have made. We started making things in the lab with PCB technology, but lately, I’ve been working with several manufacturers around the world. I have shown several prototypes for many applications—mainly medical applications—involving DNA and protein detection for different cancer diagnoses. Currently, we are working in the lab on several of the prototypes for diagnosis. It’s a proven concept. It can be done.

Las Marias: Thank you, Despina. Meanwhile, Tom and Kaspars, please tell us more about Vexos and your roles in the company.

Tom Reilly: Sure. My name is Tom Reilly, and I’m the director of marketing and sales operations for Vexos.

Vexos is a full service, high-mix, low- to mid-volume mid-tier electronics manufacturing services (EMS) provider, operating in focus market sectors such as: medical, industrial, semiconductor, automotive, safety, security and industrial internet of things (IIoT) markets. Vexos has a global manufacturing presence with two manufacturing sites in China, Shenzhen and Dongguan along with its North American sites in Markham, Ontario, and LaGrange, Ohio. All sites are ISO-9001 and ISO 13485 certified. We have more than 25 years’ experience in providing a high-level of electronic manufacturing services, value engineering solutions and global supply chain management services that supports all our sites. We are deeply involved with provisioning highly complex, fine-pitch electronics assemblies, electromechanical assemblies, full turnkey solutions and custom mechanical parts.

The medical and life sciences sector is about 10–15% of our business and we currently specialize in manufacturing a number of difference products such as; visual aid, monitoring systems, diagnostics and connectivity-type products. As we grow in this market sector, we continue to meet the needs of our customers through a range of offerings in manufacturing and engineering services. Apart from our electronic services, which include printed circuit board assembly (PCBA), sub-system assemblies, and full box-build product. Our engineering services include design for supply chain (DFSC), design for fabrication (DFF), design for manufacturability (DFM), design for test (DFT), and complementary development services.

It’s important to mention we work very closely with our customers and partners and some of the companies are world-renowned corporations, who rely on these high-level services. We also worked with smaller, localized companies to help develop and bring their products to market.

As I mentioned, we work very closely with customers and provide them with value engineering support in the early stages of product development, from quick-turn prototyping to new product introduction, right through to full mass production, whether that be localized within one of our North American facilities or one of our China facilities for a more low-cost, high-volume region. These facilities also give our customers the opportunity to launch products into the market as well.

Kaspars Fricbergs: I am the VP of quality for Vexos. I’m based in the Toronto facility, and I’m responsible for the coordination of the quality functions across the various Vexos locations. I’ve been with the organization and its predecessors for about 17 years now. I have a long background in quality in electronics and electromechanical devices, including experience in the medical realm as well. We’re ISO-13485 registered at all our manufacturing facilities, as well as ISO 9001 certified. In China, we are IATF 16949 registered in one of our facilities; and both of our facilities have ISO-14001 and OSHAS 18001 registrations as well.

Las Marias: Earlier on, Despina was telling us about her problems and challenges when it comes to the lab on a PCB. From your perspective as an EMS provider covering the medical electronics industry, what are some of the top challenges you’re seeing in this sector?

Fricbergs: There are a number of challenges associated with the field. I was about to say one of the top ones is the regulatory regime in medical devices. We are an EMS company, so we’re not design responsible, and we don’t do product submissions to the FDA; but there are a whole host of regulations surrounding the manufacture of the products that need to be met. Those are largely covered by the ISO 13485 registration, but there are also the regulatory regimes of the FDA and other local, jurisdictional regulations. In Canada, we would need to deal with Health Canada requirements as well for any products that would be marketed and sold in Canada.

The ISO 13485 certification largely covers the specific requirements that the FDA has outlined in their Quality System Regulation, 21 CFR Part 820, although there are some differences. You also have FDA regulations surrounding the use of software and the compliance of software, that’s 21 CFR Part 11. You have specific requirements for documentation, validation, traceability, validation of process, validation of software, medical device files, and medical device histories. All of that has to be in place to provide the level of assurance to regulatory authorities and to our customers that we produced the product properly according to the processes that have been defined. Some of those requirements go beyond and are different than those of other industries.

Another challenge that we often run into is simply the time to market. Often, customers can come with an immature design. It may not be manufacturable, so Vexos can help in those cases. We offer design for assembly feedback services and design for test feedback services, that can help make the products manufacturable and bring the product to market faster. Sometimes with new product launches, because our customers don’t have a strong view of the manufacturing process, they come with an idea, they may have a design that’s been provided that may not be manufacturable. Or they may not have explored all the regulatory regimes and may not be clear on what requirements they may specifically have for quality.

We’ll work with them on that, but again, a typical challenge is simply the time to market. Usually, when a design and concept have been firmed up and there’s some backing for it, the desire is to quickly get it out to market, or at least get it into the approvals stage from a regulatory point of view.

Those are some of the bigger challenges we have. Of course, we have to have a very strong eye on the product’s quality and make sure we’re complying with all the requirements and regulations in order to avoid any situation that’s going to affect our customers.

To read the full article, which appeared in the November 2018 issue of SMT007 Magazine, click here or Download and read the full PDF version

For more information on Medical Electronic Manufacturing Services – Contact VEXOS today!  or Call 855-711-3227

Vexos, is a mid-size global Electronics Manufacturing Services (EMS) and Custom Material Solutions (CMS) company, providing complete end-to-end supply chain management solutions in electronic and mechanical products for Original Equipment Manufacturers (OEMs) and new emerging technology companies.  

Vexos services extend over the entire electronic product life cycle, from value engineering services for product development to prototyping and New Product Introduction (NPI) through to the growth, maturity and end-of-life phases with a strong focus and commitment to quality and customer service satisfaction.

With facilities in United States, Canada and China Vexos can efficiently compete in today’s marketplace, primarily focus within automotive, industrial, networking, communication, medical and security market segments.  Vexos enables their customers to focus on their core business, reduce your cost, speed your time-to-market and gain a competitive advantage.

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Best Practices in Manufacturing: Wave Soldering https://www.vexos.com/2018/07/31/best-practices-in-manufacturing-wave-soldering/ https://www.vexos.com/2018/07/31/best-practices-in-manufacturing-wave-soldering/#respond Tue, 31 Jul 2018 14:00:00 +0000 https://vexos.com.superdorx.com/?p=989702 Over the years, best practices have evolved and will continue to evolve with the changing environments, company needs and challenges and what may work for one company may not necessarily be best for another. A common area sometimes overlooked versus surface mount is wave solder, which can commonly introduce significant touch up and rework if…

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Over the years, best practices have evolved and will continue to evolve with the changing environments, company needs and challenges and what may work for one company may not necessarily be best for another. A common area sometimes overlooked versus surface mount is wave solder, which can commonly introduce significant touch up and rework if not appropriately managed.

The following recommendations are based on experiences and best practices and is not intended to be considered hard and fast rules, but rather guidelines—your situation will dictate which practices work best for your company.

This article will be focusing on common wave defects and best practices to both address, predict and proactively prevent these issues from reoccurring. Contributing elements such as component selection/ considerations, design, tooling and process will be discussed.

By far the most common wave defect is bridging, which is the unwanted formation of solder between conductors. Defect contributors include component, design, tooling and process.

Solder Bridging

Component Considerations

Lead Length – Specification of component lead length in the design vs. the PCB thickness provides the respective protrusion of the lead into the solder during this process.  Ensuring the lead length is neither too short (i.e. solder cannot reach the pin to achieve capacitary action) or too long (i.e. provides a pathway for webbing from one pin to the adjacent) can prorogate bridging for the assembly.

Best practice when specifying the component lead length is to ensure the lead length is long enough to provide the necessary heat transfer for proper wicking to provide sufficient barrel fill while neither exceeding the maximum protrusion specified as per IPC-A-610. A good rule of thumb is the length should not be longer than the distance between the two adjacent annular rings. By ensuring this is met, the probability of webbing is significantly reduced as surface tension will draw the solder to the nearest copper area.

In cases where the lead length is too long, component prep and lead trimming are recommended to provide the desired length.

Figure 1: Bottom side surface mount component heights can drive thicker pallet requirements and further impact the ability of the solder to flow in and out of the pocket.

Other considerations related to the components themselves can be PCB contamination, component contamination, oxidation or solder mask issues.

Design Considerations

Component Orientation – Particularly relevant to larger pin count connectors with at least 2 or more rows where orientation of the connector parallel to the wave can be result in significant bridging occurrences. 

Best Practice to address is to ensure larger pin count connectors are orientated perpendicular to the wave to minimize the number of exposed trailing end pins of the connector where bridging is likely to occur.  This is especially true for fine pitch.  In situations where orientation cannot be accommodated, other methods such as solder thieves (effectively non-functional pads or copper features which are placed on the trailing edge to pull the solder away from the last lead to prevent bridging) can be designed either into the board or onto the selective wave pallet to minimize bridging. 

Tooling Considerations

Some best practices in selective solder pallet design include proper PCB orientation in the selective wave pallet. It is recommended to angle the board between 15-30 degrees can help mitigate the bridging to a few pins by ensure only a handful of pins end up as trailing pins.  This is especially helpful where larger pin connectors are designed parallel to the wave direction.

Sufficiently large wave openings and solder flow channels on the bottom of the wave pallet provides sufficient solder flow and flux application preventing pooling or areas where solder is trapped resulting in bridging.  Generally, constraints such as minimum clearance from the outside edge of the annular ring to a surface mount pad drive the opening size.  Recommendation is 0.100” for this distance for proper design.

Bottom side surface mount component heights can drive thicker pallet requirements and further impact the ability of the solder to flow in and out of the pocket.  The aspect ratio relates to the solder opening length/ width versus the vertical travel required for the solder to reach the bottom of the PCB.  The minimum ratio is 1:1 for leaded solder but increases to 1:3 for lead free solder.  i.e. if the length/ width is 0.150” then the maximum vertical dimension is 0.150”, for leaded solder.  Violating this aspect ratio will obstruct proper flow and increase the chance of wave related defects.

Additionally, orientating the board on selective wave pallet at 15 degrees can help mitigate the bridging to a few pins, typically a hybrid solution of the above techniques provides the optimal solution.

Process Considerations

Selecting the right flux for the application as well as the appropriate thermal profile can have a significant impact on the formation of solder bridging and selecting an appropriate flux for the thermal mass and heating profile required can have a significant impact on overall yield.

Generally, a higher solid content is more robust at higher temperatures and water-based fluxes do not perform as well at higher temperatures and better suited for lower thermal boards.  Ensure the pre-heat temperature and dwell time for your board is appropriate for your flux can mean the difference between a good and bad result.  Burning off the flux prior to wave can result in bridging.

Lifted Components

Another common defect is Components Lifted after wave which is more predominant on smaller components such as axial or radial components (but just as common on connectors and other components) which are lifted during contact with the wave and are soldered in placement.  The most common practice to address is through component lead pre-forming and/or pallet hold downs.

Component Considerations

Ensuring components such as axial and radial components are properly prepped can avoid most lifting situations.  Lead forming or clinching of the leads which mechanical hold the components in place are by far the most common.  Common with bridging, leads which are too long can also exaggerate lifting which acts as a lever to push the component out of position. 

Tooling Considerations

Other components such as connectors which cannot easily be retained in place require additional hold downs which can be in the form of glue or over-clamps as part of the selective solder.

When considering over-arms for clamping, the additional thermal mass introduced by these features and must be considered into the profile and may potentially require a different flux for better performance.

Process Considerations

Wave height and the use of lambda vs. laminar flow can also contribute to increased occurrences of component lifting.  Ensuring wave heights are set to no more than 50% of the PCB thickness relatively to the pallet and the use of turbulent flows should be minimized. 

Other considerations include conveyor vibration, angle, etc.

Insufficient Solder

Another most common wave defect is insufficient solder and can be categorized as incomplete barrel fill or incomplete circumferential wetting.

Related but typically more related to contamination of the solder, board or component is de-wetting or non-wetting.  For the purpose of this review we will assume the components are in good condition prior to processing.  Best practices to prevent introduction of these types of defects include a well-established incoming inspection process combined with solder dip testing as per IPC-TM-650 for suspect contaminated or oxidized components.

Design Considerations

Common design considerations are direct connection of plated through holes to large copper planes which act as a heat sink during wave soldering.  To address, best practice is to provide thermal relief in these areas to allow proper flow during soldering.  Thermal spokes provide isolation and can significant increase the probability of a good joint.

Figure 2: The direct connection of plated through-holes to large copper planes acts as a heat sink during wave soldering. The best practice is to provide thermal relief in these areas to allow proper flow during soldering.

Other considerations include component lead diameter to plated through hole diameter ratio mismatches.  A plated through hole that is either too large or too small vs. the lead can equally result in insufficient. Recommended aspect ratio is typically 0.6 larger than the component lead will provide good results.

Process Considerations

Generally, this comes down to heat transfer or insufficient flux as either can have an equally significant impact on solder fill.   Lack of flux penetration or presence due to profiles which are too hot are the most common root causes.

Products such as Fluxometers which use acid paper and specially design PCBs with regular spaced plated through holes can be used to ensure the appropriate amount of flux and penetration (i.e. pressure) is applied for optimal use.

Regular or monthly reviews including lev-checks or wave riders can also provide an indication of the wave levelness, temperature profile and overall oven performance and is recommended to ensure process drift related to the equipment is not a contributor to defects.

Figure 3: A Fluxometer can be used to ensure the appropriate amount of flux and penetration is applied for optimal use. 

Solder Voids

Solder Voids or Out-gassing (Blow Holes and Pin Holes) occurs when a solder joint has a small hole that penetrates the surface of the solder connection.  This is typically due to moisture entrapment that during the soldering process out gasses from the joint.

Process Considerations

Like components, printed circuit boards are also moisture sensitive however commonly are not treated in the same manner as moisture sensitive components.  As a general rule, all PCBs should be considered MSL 3 and be managed as any other Moisture Sensitive Device. 

Best Practice is to ensure PCBs are sealed and only opened just prior to use.  Extended periods between thermal cycle operations like surface mount reflow and wave should be considered when reviewing exposure time.  If a board is not soldered within 72 hours after the previous thermal cycle operation, it should be baked to remove excessive moisture in accordance with J-STD-033 or kept in a dry cabinet with a relative humidity <5% to minimize the risk of such occurrences.

Solder Balls

Solder Balls and Spatter defects are generally where a small sphere of solder adheres to the laminate, resist or conductor after wave soldering.  There are typically 3 types, random, non-random and splash back which are all typically process related.

Process Considerations

For Random solder balls, these are the easiest to address and are typically a result of an excessive flux prior to wave, uneven wave height.  If you hear a “sizzle” while the board is going over the wave solder it is a good indication that the pre-heat is either too low or the flux application is too high  or the wave temperature is set too high.

For non-random solder balls which the balls appear in the same location or trailing pin this is most commonly due to insufficient flux or pre-heats are too high.

For Splash back this is most commonly due to the wave height being too high or excessive turbulence in the wave.  95% of applications if designed appropriately can be soldered with laminar flow only and is recommended to help avoid occurrences.

Best practice is to utilize tools such as the Fluxometer and Waverider to check for parallelism and proper flux optimization to minimize such occurrences.

Tooling Considerations

Areas of entrapment in the wave pallet can also contribute to solder balls, reviewing pallet designs for solder flow to ensure there is sufficient flow channels or vents to allow outgassing during soldering can help minimize the occurrences of solder balls and spatter. 

Icicles, Flags and Excessive Solder

Icicles & Flags (Horns) and Excessive Solder occurs when a printed circuit board passing through a soldering process and either collects too much solder or develops an undesirable protrusion of solder from the joint.  The most common contributor is process.

Process Considerations

By far the most common reason is the wave solder pot temperature is too low or insufficient dwell on the solder pot.  Best practice of 3-5 seconds of dwell is recommended for a proper joint formation.  Tools such as Oven-riders can provide an indication of solder pot temperature drift is occurring, it is always recommended to measure the solder pot temperature regularly to ensure proper temperature.  Wave Solder pot temperature readings from the machine do not always translate to actual and must be monitored.

Defect prevention is best performed through applying best practices through formalized design reviews and implementing process controls around key wave parameters such as solder pot temperature, pre-heat, dwell, parallelism and flux optimization.

Activities such as Design for Manufacturing (DFM) or Design for Assembly (DFA) can save significant time in applying design rules to ensure PCB design considerations, thermal requirements, manufacturing compatibility and related contributors are identified early in the design cycle where changes can be implemented at a fraction of the cost.

It is important to align with strategic manufacturing partners early on to provide relevant design feedback on all aspects on the design as the design decisions made early on can affect the long-term viability and cost of the product for the total lifecycle.

For more information on Best Practices in Electronic Manufacturing – Contact VEXOS today!  or Call 855-711-3227

Vexos, is a mid-size global Electronics Manufacturing Services (EMS) and Custom Material Solutions (CMS) company, providing complete end-to-end supply chain management solutions in electronic and mechanical products for Original Equipment Manufacturers (OEMs) and new emerging technology companies.  

Vexos services extend over the entire electronic product life cycle, from value engineering services for product development to prototyping and New Product Introduction (NPI) through to the growth, maturity and end-of-life phases with a strong focus and commitment to quality and customer service satisfaction.

With facilities in United States, Canada and China Vexos can efficiently compete in today’s marketplace, primarily focus within automotive, industrial, networking, communication, medical and security market segments.  Vexos enables their customers to focus on their core business, reduce your cost, speed your time-to-market and gain a competitive advantage.

Brain Morrison, VP of Engineering for Vexos, is directly responsible for process, test, and development, focused on new customer and new product introduction. Morrison aided in the development of the company’s corporate technology roadmap, systems and processes, value engineering, environmental management, and manufacturing initiatives to drive lower cost, flexible solutions, and manufacturing innovation.

 

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