What Is Tenting Via & How It Plays Important Role In PCB Fabrication?

By | Date posted: | Last updated: September 3, 2020
PCB Tenting Vias Fabrication

When it comes to establishing connection patterns between the various layers of a board, vias play an extremely important role. Simply put, vias are holes on the PCB without which the connections cannot be formed and therefore the PCB would not work.

They are often covered with different materials as this helps in the twofold process of:

  • Helping in conducting electric signals
  • Dissipating heat

While this may be thought of as a fairly straight-forward process, the fact is it is quite a specialized process when it comes to PCB fabrication.

Quite often, vias are copper-plated. However it depends on the PCB design whether the holes are covered or exposed. When the via or the hole is fully covered, it is called a masked or a filled via. On the other hand, PCB designers can also use another method called tenting, which is quite popular.

What is tenting via and why is it done in PCB Fabrication?

As its name suggests, tenting via implies creating a tent like shape over the hole. This is done so that the numbers of exposed conductive pads on the PCB are limited.
The process of tenting entails using a solder mask to enclose the opening. Whether or not you should use tenting in the PCB fabrication really depends upon the design of your board.

Below are the benefits and limitations of using tenting in PCB fabrication service:

Benefits of tenting a via

The foremost advantage that tenting vias offers is the protection offered by the solder mask. The tenting creates a barrier that ensures there aren’t any damages to the PCB layers. This is akin to how the solder mask prevents corrosion in the copper traces.

Another advantage of the tenting method is also that the numbers of exposed conductive components are minimized. The exposure of these components can result in corrosion. Tenting also helps in significantly bringing down the possibility of a short on account of the solder bridging. With tenting, you can also rest assured that the paste migration from SMT pads is significantly reduced.

The fact that tenting is a cost-effective method of protecting the vias is an added perk!

Limitations

A major limitation of the tenting process is that with a liquid solder mask, there is always the possibility of breaking of LPI and creating small holes in the tent. In turn, these holes can trap moisture and corrosion can be the natural outcome.

To overcome this limitation, it is important that the vias are left exposed in the prototype stage. That way, any issues can be identified and the traces can be fixed. With covered vias the opportunity to discover these issues is significantly limited.

How to make the decision to tent a via?

Two major aspects go in to decide whether or not you should tent a via. The first, of course is the PCB design and the second is the size of the via.

As a thumb rule, tenting works well with vias of smaller diameters of 12 mil or less. Any via that is above 12 mil in diameter does not lend itself to tenting. If you need to take care of large vias closing it with some kind of fill is a far better alternative.

Tenting is also preferred on account of its lower cost as opposed to mask plugging or epoxy filling. In fact tenting via with a liquid photo-imageable solder mask turns out to be the most cost-effective. However where there are concerns about tenting being loose, epoxy filling is an alternative, even though it comes at a higher cost.

Your PCB fabrication requirements along with tenting via!

With more than 4 decades of experience in PCB Fabrication USA, at TechnoTronix we have the technology and production facility to offer the tenting of vias with the highest degree of accuracy. With our experienced engineers you can rest assured that what you will get is an effective production. Little surprise then that clients across industries rely on us for their PCB fabrication, California requirements. Our ability to deliver, unparalleled quality as well as customer service, is what makes us stand out. Both on-time delivery and price competitive products are our USP. The most important element of our success, however, has been the relationships we have developed with our customers.

If you are looking for full fledged PCB fabrication services from product layout, manufacturing to warehousing and shipping, please explore our PCB fabrication services!

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Enhance the Quality of PCB Fabrication with HDI PCB Technology!

By | Date posted: | Last updated: August 14, 2020
quality pcb fabrication

If there is one trend when it comes to electronic devices, it has to be that of miniaturization. The size of electronic devices is shrinking and their complexity is on the rise. What this, in turn, means is the increase in demand of small PCBs. There is, therefore, a corresponding increase in the technology that can facilitate these small sized PCBs.

This is the exact reason why High Density Interconnect or HDI, as it is popularly called, is becoming increasingly relevant in today’s times.

What exactly is HDI technology?

Essentially, HDI technology is a result of evolution in component packaging that facilitates the construction of small boards that can have a large number of components per square inch. Simply put, an HDI PCB, therefore, has higher wiring density per unit area, as opposed to a conventional board. HDI PCBs are PCBs with one or all of the following:

  • Microvias
  • Blind vias
  • Buried Vias
  • Other microvias
  • They also have built-up laminations and high signal performance.

In fact, it is the Microvias that have a huge role to play when it comes to the capabilities of HDI PCBs. Since smaller vias can be close to each other, the board requirement is small. Also, space is easily freed up for additional components. With Microvias also having smaller aspect ratios that through-hole vias, the reliability quotient of HDI boards is far higher.

Importance of Using HDI PCB Fabrication

A typical PCB has one or two layers, while multilayered PCBs can have up to 20 layers depending on their complexity. When it comes to HDI PCB, however, it could have as many as 40 layers which have densely mounted components, fine lines and micro vias. Some of the advantages of using HDI PCBs include:

  • The ability to have several permutations and combinations when it comes to the layers.
  • If you are looking for coreless designs, HDI PCBs come in handy
  • With via-in pad, what you can also have is the maximum number of components in minimal number of layers.
  • When it comes to mission-critical applications, The importance of HDI PCBs increase manifold.
  • They offer the highest level of accuracy
  • They have a better signal speed. The signal integrity is improved on account of shorter distance connections as well as lower power requirements.
  • Some of the other performance improvements of HDI PCBs include stable voltage rail, lower RFI/EMI, distributed capacitance.
  • It facilitates small cores and allows for fine drilling
  • It also facilitates microvias
  • It decreases power usage
  • It is extremely cost effective
  • It goes a long way in improving the overall performance of the device
  • On account of the design efficiencies that HDI PCBs offer, it also allows for faster time-to-market, which is a significant source of competitive advantage in today’s times.

Applications of HDI PCBs

HDI PCBs are used in a wide range of industries, especially where miniaturization is prevalent. These would include digital devices, automobiles, aircrafts and more.

Another area where HDI PCB Fab finds a lot of application is to do with medical devices. With the need for small devices with high transmission rates, HDI PCBs fit the bill. This is especially true of implants but also of other medical equipment such as CT scans, MRI equipment and more.

The TechnoTronix advantage

At TechnoTronix, we have over 40 years of experience when it comes to manufacturing high quality PCBs. Our superior technical expertise ensures that we design custom made HDI PCBs for your bespoke requirements at competitive prices. We cater to a wide range of industries including but not limited to:

  • Aerospace
  • Defense
  • Telecommunications
  • Medical PCB Prototype
  • Industrial PCB Prototype
  • Renewable Energy PCB Prototype
  • Rigid-Flex PCB Technology

The other advantage with our PCB Fabrication, California lies in the fact that we offer fast prototyping and consistent delivery of high quality products with quick turnaround times. We run extensive DFM tests to ensure that there are no costly errors later. The fact that we are an ISO 9001:2015 AS9100 Rev D company with unstinting focus on quality when it comes to PCB Fabrication ensures that you can rely on our services.

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The Effect of Woven Glass Laminates on PCB

By | Date posted: | Last updated: November 14, 2017
pcb fab

When it comes to increasing the structural strength of PCB materials, woven glass is an obvious choice. It adds significantly to the mechanical stability of the laminate rendering it high structural strength. In fact, the use of woven glass in PCB fabrication dates back as early as to the 1960s when they added high tensile strength and stability to the substrate. In addition, glass fibers also bring the added advantages of high thermal as well as chemical resistance, insensitivity to moisture as well as the advantage of being an electrical insulator. In the early days, however, there was little concern about considering the effect of inhomogeneity in the resultant substrate. However, today it is also important to understand how the properties of components affect the behavior of the whole.

Very often concerns regarding the negative impact of woven glass, in terms of electrical performance, come to the fore. The “glass weave effect” is feared to impact the performance of high- frequency circuits. Here is an overview of factors that impact the glass weave phenomenon:

It is a possibility that on account of the woven glass laminate, the Dielectric Constant or Dk as it is popularly known as, varies across areas. So, in areas where glass bundles are present, the Dielectric Constant is high, while in open areas between the bundles, the Dk is low. The variation can be as high as between 6 in areas of glass bundles and 3 in open areas. Since Dk is an important metric, the variation in Dk is a cause for concern as far as circuit designers are concerned. Dk variation can impact performance particularly at higher frequencies of 30 GHz and above, also referred to as millimeter-wave frequencies. When the electromagnetic wave faces a change in the Dielectric Constant or Dk, propagation can be impacted and resonances may occur. The impact can be seen even when the anomaly is as small as one-eighth of a wavelength. With woven glass stacked to form a laminate, it is less likely for glass bundles and openings to align. Consequently, it is less likely for discrete Dk variations. In cases where two or more layers of glass are used, therefore, the impact of the glass weave effect is decreased.

The bigger issue regarding the glass weave effect, plays out when circuits use a laminate which has a single layer of woven glass. The fear also is to do with the random impact of the glass weave effect and how it will play out in case of high volume production. On account of the glass weave effect there can be performance variations from one circuit to another. Often changes in the phase angles of high frequency waves is noticed which in turn impacts phase based modulation.

This is not to say that using multiple layers of woven glass fabric can overcome all the issues related to the glass weave effect. Often differential conductors on a single layer circuit can bring about a new set of issues. In case the Dielectric constant or Dk values of the wave propagation medium varies between the pair of lines, the phase angles are impacted. This in turn, results in a slowing down of the propagation of one signal wave over the other and results in a skew. Particularly in high speed circuits, this can affect performance.

However, fortunately there are ways to tide over this issue. Changes in Dk can be stemmed by using a laminate with a filled resin system. The use of the filler results in less variation in Dk. The combination of glass fabric, resin and filler, in fact averages out the variation in Dk values thereby ensuring that performance is not impacted.

Yet another way to ensure that performance isn’t negatively impacted, is to use flat glass fabric along with minimizing the relative glass content in the laminate. This also goes a long way in minimizing the variation in Dk. The use of spread glass is also beneficial as it offers the ability to wet the fibers which allows a chemical bond to be formed between the glass reinforcement and the resin. This in turn, is a significant improvement over using traditional tightly bound bundles of glass fibers which can lead to defects in the interface.

The way to overcome the glass weave effect totally, of course is to not use woven glass at all. There are ceramic filled laminates that ensure that the dielectric constant or Dk is maintained in a certain range across the circuit board. This consistency, in turn, works well for small wavelengths as also for coupled lines.

In future PCB substrates will use even better fibers and resins to produce more advanced and functional materials that will add to the performance.

To get more insights into the PCB fabrication, assembly, Layout and prototyping services, visit http://www.technotronix.us/ also you can drop an email to sales@technotronix.us or give us a call at 714/630-9200 to solve your queries or to get a quote.

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Why Silkscreen Is An Important Method Of PCB Fabrication?

By | Date posted: | Last updated: November 14, 2017
pcb fabrication

The term silkscreen has derived its name from the process of using a stencil on a PCB. Also referred to as legend, it refers to the text-based information that is printed on a circuit board. This includes information such as component references, company logos, component identifiers and more. It is commonly used on the component side to identify various components although sometimes it is used on the solder side as well. However using two silk screens tends to increase the cost. The standard colours are Black, white and yellow, although other colours can also be requested. Similarly silk screening can be done in a whole lot of fonts. However, the important thing to remember is the readability of the font.

Traditional silk-screening requires polyester screens stretched on aluminum frames. Besides this you need a laser photo plotter, a UV printer, spray developer and curing ovens.

Presently silk screening can be done in either of three ways:

  • Manual screen-printing – This can be done when line widths are greater than 7 mil and its registration tolerance is 5 mil. While this allows for easy set up and application, it requires large texts and line width size. Also in terms of accuracy it isn’t the most desirable option as the output depends on a number of factors such as viscosity and age of ink, room temperature, amount of humidity, pressure of stroke and more.
  • Liquid Photo Imaging or LPI– This method is used when line widths are greater than 4mil. This is known to provide more accuracy than manual screening. However this has longer set up time and is known to use more ink.
  • Direct Legend Printing or DLP– This method is highest in terms of accuracy but also comes at a higher cost and also does not work on silver surface boards. Also not all fabricators have DLP Printers.

A well-designed silk screen plays a very important role as it can reduce both the likelihood of error as well as the time taken to spot the error. This is true both for the assembly process as well as during the rework phases. In fact, it isn’t sometimes necessary for the process to identify all the passive components that make up the devices on the board. Instead, it is enough if the silkscreen mentions the circuit functionality. In fact, for a PCB packed with many small components this is a far more achievable objective than labeling each and every individual component. While active components can be labeled, the passive ones need not be. Choosing to identify the circuit functionality instead of all the passive components, in turn, ensures that the silkscreen legend is useful as well as legible.

In fact a detailed understanding about silk screens can also go a long way in reducing PCB Costs. For example, silk-screening on one side only can reduce artwork costs. Similarly, restricting yourself to standard colours during the silk screening process can impact the cost of PCB fabrication, while keeping its benefits intact.

Technotronix is one of the kingpins in offering PCB layout and manufacturing solution to all predominant industries. With a strong team of technical professionals, it has gained expertise in providing silk screening process to reduce PCB artwork cost used in PCB Fabrication. Our key success factor to achieve new heights in technological innovations is continuous improvement and high quality standards. To get insights into our PCB services offered, visit http://www.technotronix.us. Why not give a call or drop a mail? Visit http://www.technotronix.us/contact-us.html.

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