A Comprehensive Guide for Multilayer PCB Fabrication Process!

By | Date posted: | Last updated: May 28, 2021
Multilayer PCB Fabrication

Multilayer PCB Fabrication is a complex process that requires expertise to master. Multilayer PCB assembly is quite a complicated task, there are several factors that affect the costing of Multilayer PCB assembly. But, as we are talking about the process of multilayer PCB Fabrication, here is a quick overview of the many aspects that make up the entire process of multilayer PCB Fabrication:

Checking design for manufacturability (DFM)

Once your PCB design is ready, you would be in a position to send the output files to a fabricator. What the fabricator will do is to make sure that the design works and that it is possible to build the board as per the design provided by you. With this check underway, the design output data will be used to create images. There are different tools that can be used by the fabricator such as:

  • Photoplotter

  • Direct Imaging technique

The fabricator will use either ultraviolet light through a process of photolithography or use a focused laser beam.

Inner layers for Multilayer PCB Fabrication

The inner layers of the PCB are typically made up of FR-4 material. The inner layer laminate is thus created, by bonding copper to the core material. The photoresist material is coated on the copper and one layer image from the PCB CAD data is exposed to the photoresist. The basic principle behind this, is that the exposed areas will harden while the unexposed ones, remain soft and pliant. The areas of unprotected copper can now etched away. Once the etching process is done, the hardened photoresist is removed.

The step now needs to be followed for each layer of the multilayer PCB fab. The next step is a process of thorough inspection through automated systems to ensure that there is no room for error.

Lamination in Multilayer PCB Fabrication

This step involves the use of prepeg, which is a sheet of fiberglass along with epoxy resin. The inner layers are then stacked along with prepeg to ensure there is alignment. The top and bottom prepeg layers are covered with copper foil. Now comes the final step of the lamination process whereby the entire unit is heated and the layers are fused into a circuit board.

Next comes the process of drilling and application of copper on the interior of the drilled holes.

Just as the inner layers were created, it is now time to add the top and bottom circuitry. The circuitry is then plated and covered with tin. It is time now to remove any remaining photoresist as well as etching away of extra copper and finally removing the tin.

Final touches

This step involves applying the solder mask. Post that, the choice of surface finish, silkscreen and markings are applied. A professional PCB fabricator is fully equipped to offer a wide range of surface finishes that the project demands.

Now comes a very important step in the process of multilayer PCB fabrication. This step is that of electrically testing the board. Post this there is a final inspection.

Clearly then the entire process involves a lot of expertise and precision. The litmus test of whether the PCB is built correctly begins at the design stage itself. With the use of proper design tools you can, in turn, ensure proper component placement, correct spacing etc. during fabrication. It is this expertise and precision that in turn results in boards that are:

  • Light weight and small
  • Are high on flexibility
  • Lend themselves to high capacity and speed

Whether you are looking at a board with a few layers or complex boards up to 24 layers, what you will get is complete commitment to quality. In addition, we have some extremely stringent testing protocols that ensure that the boards never let you down!

At Technotronix, we have over 4 decades of experience in multilayer PCB fabrication. You can rely on our PCB design tools that, in turn, lead to that perfect PCB fabrication. An improper design can lead to a wide variety of issues such as imbalance.

Asymmetrical designs, for example, can lead to twisting or bows. It is extremely important, therefore, to go with a partner who understands these issues. Our experienced staff has a robust body of industry knowledge that ensures that you avoid costly mistakes later. Our superior engineering capabilities mean that each board matches your exact requirements and technical specifications. In case if you have any questions, please feel free to contact us via email at sales@technotronix.us

PCB Fabrication Process for Type of FR4 Semi Flex PCB!

By | Date posted: | Last updated: April 15, 2021
PCB Fabrication Process

When it comes to PCB fabrication, the importance of flex-rigid PCBs cannot be overstated. The one driving reason for it is the growing trend of miniaturization of products. Besides, with the flexibility and the capability to be 3D assembled, the demand for flexi-rigid PCB is on the rise. However, not all PCB manufacturers are able to cater to the complex flexi rigid printed circuit board fabrication process. Semi-flexi printed circuit boards are manufactured through a process, which brings the thickness of a rigid board down to 0.25mm +/- 0.05mm. In turn, this allows the board to be used in applications, which require bending the boards and fitting them inside casings. The boards could be used in one-time bend installation as well as in multi-bend installations.

Below is an overview of some its properties that make it unique:

Properties of FR4 Semi-Flexible PCB

  • The most important property that lends itself to multiple use is the fact that it is flexible and can adapt to the available space.
  • The fact that its flexibility does not come in the way of its signal transmission, adds to its ubiquitous use.
  • It also lends itself to being light-weight.
  • Typically, semi-flex PCBs are also known for their optimal costs as their fabrication procedure is compatible with the existing manufacturing capabilities.
  • They save time both during the design phase as also during assembly.
  • They are an extremely reliable alternative especially as they avoid many issues including entangling and welding.

PCB Fabrication Procedure

The broad procedure for fabricating FR4 Semi Flex Printed Circuit Boards is as follows:

The process broadly covers the following aspects:

  • Material cutting
  • Dry film coating
  • Automated Optical Inspection
  • Brownization
  • Lamination
  • X-ray inspection
  • Drilling
  • Electroplating
  • Graphics Conversion
  • Etching
  • Silkscreen printing
  • Exposure and development
  • Surface finish
  • Depth-controlled milling
  • Electrical test
  • Quality Control
  • Packaging

What are some of the issue faced and plausible solutions in the PCB fabrication process?

The big issue in fabrication is to ensure accuracy as also tolerance of depth-controlling milling. The important bit is to also ensure that there are no resin cracks or oil peeling that leads to any quality issues. This involves checking for the following aspects during depth-controlling milling procedure:

  • Board thickness
  • Resin content
  • Milling tolerance

Depth Controlled Milling Test A

The thickness milling is performed with the Mapping method to conform to the thickness of 0.25 mm, 0.275 mm and 0.3 mm. Post this the board is subject to testing to see if it can adhere to the 90-degree bending. Typically, if the remaining thickness is at 0.283mm, the glass fiber is deemed to be damaged. It is imperative, therefore, to consider the board thickness, glass fiber thickness as well as the dielectric situation, in carrying out the depth milling.

Depth Controlled Milling Test B

Based on the above it needs to be ensured that the thickness of copper between solder mask and L2 is in the range of 0.188mm to 0.213 mm. Due emphasis also needs to be paid to any warpage that may occur thereby impacting the uniformity of overall thickness.

Depth Controlled Milling Test C

Post the prototyping of the panel, Depth control milling is important to ensure the size is set at 6.3″x10.5″. Post that, mapping point measuring is undertaken to ensure that the vertical and horizontal intervals of 20 mm are maintained.

With a special fabrication method, it is ensured that the tolerance of the deep controlled thickness lies in the range of ±20μm.

At Technotronix, we combine state-of-the-art technology with our advanced engineering to offer you semi flex printed circuit boards of the highest quality. With over four decades of experience in delivering high quality, on-time, price-competitive products, you can bank on us for your PCB requirements. Our Semi-Flexible FR4 Printed Circuit Boards are used across a wide range of industries and are available at the best turnaround times. What this additionally means for you is quick time-to-market which in turn, adds to your competitiveness. The fact that they are priced competitively means that you will be well within your budgets.

To get more insights into the PCB fabrication and PCB assembly services, please explore our PCB fabrication services. 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.

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

By | Date posted: | Last updated: February 14, 2022

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!


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!

Enhance the Quality of PCB Fabrication with HDI PCB Technology!

By | Date posted: | Last updated: April 8, 2022
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 printed circuit boards with one or all of the following:

  • Microvias
  • Blind vias
  • Buried Vias
  • Other microvias
  • They also have built-up lamination 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 printed circuit boards. 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 multilayer PCB 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 for HDI PCB Fabrication

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

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