Challenges & top considerations to make your high-speed board design project successful!

By | Date posted: | Last updated: February 15, 2022
High-Speed Board Design

Two decades ago, if you spoke of high-speed data rate, you were in all probability referring to 3 Gbps. Today, of course, engineers can be dealing with as much as 25Gbps. While we are pushing for faster rates, we are also parallelly making smaller devices given the trend of miniaturization.

With high speed also come a number of challenges, primary among them being interference. In fact the faster the data rates, the harder it can get to protect the integrity of signals.

Making your high-speed board design project success, therefore, involves paying attention to a number of factors.

Here are some of the aspects to watch out for High-Speed Board Design:

Have a plan in place

This might sound like an obvious thing to do, but the fact remains that without a proper plan in place you are likely to suffer a whole lot of setbacks. The plan needs to include aspects such as:

  • Having a visual diagram for the sub-circuits and return current.
  • Knowing the frequency and fastest rise time of each signal.
  • Having a plan to meet requirements for differential signals, controlled impedance and more.
  • Documenting voltage and power requirements.

Document details of your board stackup

It is important to determine which material you will be using for the board and what are the specific constraints that need to be followed in terms of the design rules. FR4, for example, works well when you are working with speeds < 5Gbps. When it comes to between 5-25 Gbps clock speeds, Nelco, SI or Megtron work well. For high-speed designs, Rogers as a material is known to work well. Once the PCB material has been chosen, layer stackup strategies need to be kept in mind. Some of these include:

  • Placing a signal layer adjacent to a plane layer
  • Routing high-speed signals on the inner layers of the board
  • Using multiple ground planes to lower reference impedance.

Power and Ground Planes

The ground plane should not be split with any routed signals. Split it can lead to EMI and signal timing issues. In case a ground plane has to be split, a 0 Ohm resistor needs to be added.

Keeping size of land patterns minimum

With high-speed designs since the board real estate is at a premium, you need to save space. To this end, the minimum oversize of the pads should be kept at 0-5% of the size of the component pins. Also, the less the space given to vias, the more room there is for differential pairs, vias and more.

Route Signals for Maximum Shielding Benefits

To ensure that signals do not interfere with each other or with any component, some of the guidelines to be followed include:

  • Ensure you do not keep long, parallel signals
  • Maintain distance between signal traces
  • Route signals orthogonally

Path for Current Return

Using vias to return currents to their termination is recommended. Ensure also that the vias are impedance matched, differential vias. Return vias also need to be placed close to signal vias.

3W Rule

The 3W rule comes in handy to minimize coupling. The rule states that the separation between traces must be equal to three times the width of a single trace from center to center.

20H Rule

To prevent coupling between power and ground planes, it is advisable to sue the 20H rule. It states that the power plan must be made 20 times smaller than the dielectric thickness between adjacent power & ground planes.

General Routing Guidelines

When it comes to routing guidelines, the following tips will come in handy:

  • Avoiding 90-degree angle bends in your traces.
  • Length match tuning in the PCB design software is necessary.
  • Designing transmission lines with the use of microstrip or stripline traces is imperative.

To sum up

Overall arming yourself with strategies and knowledge to combat issues such as interference can go a long way in maintaining integrity of signals. Choosing the right electronics contract manufacturer who has the necessary experience, expertise and access to industry best practices is something that you must do in order to make your high-speed design successful.

We have over 4 decades of experience in providing innovative high-speed PCB design & manufacturing services. We take an extra step to reach out to your exact PCB manufacturing requirements, high-quality standards, and a strong customer support service to provide quick turnarounds and on-time delivery to our customers. In case you have any questions, please feel free to contact us via email at [email protected] or call us on 714/630-9200.

The Importance of FCT Testing in PCB Manufacturing & Assembly!

By | Date posted: | Last updated: January 24, 2022
FCT Testing

While it is important to stick to the highest quality standards in the process of PCB manufacturing, what is equally important is that you ensure that your board will operate as envisioned. This requires undertaking a set of tests at various stages namely prototyping, manufacturing as well as assembly.

PCB functional testing (FCT testing) comprises a whole range of tests that check for proper functioning of the board. Oftentimes, the manufacturer may also need to modify the PCB design for FCT in order to facilitate PCB functional testing. As long as the manufacturer understands your device’s functional requirements as well as your testing requirements, there will not be too many requirements for sending the design files back and forth. A cloud-based system for data access of course works best.

Let us look at PCB Functional Testing (FCT Testing) in some detail:

Simply put, PCB functional testing refers to a comprehensive testing regimen that determines that a manufactured board is ready to serve its purpose. The goal of PCB functional testing is to identify any defects that could impact its reliability. The defects could be by way of any missing components or as simple as any opens or shorts. PCB Functional testing, therefore, entails a wide variety of tests including but not limited to:

  • Visual Inspections
  • In-Circuit Tests
  • Flying Probe Tests
  • Bench Tests

Above everything else, PCB functional testing (FCT Testing) offers a comprehensive view of signal behavior. Some of the potent signal issues that can be identified through a PCB functional test include:

  • Power integrity issues: PCB functional testing can bring to light any issues such as jitter, low frequency noise, and more.
  • Signal distortion: Signal distortion, Skews and other such behavior can be identified through comprehensive functional testing.
  • Incorrect voltage: Incorrect Voltage can often be a result of a missing or incorrect component.

Comprehensive PCB functional testing involves building a custom test fixture. While this comes at a cost, with high volume manufacturing runs, the cost tends to quickly amortize itself, especially as it guarantees high quality

The Benefits of PCB Functional Testing (FCT Testing) Methods

  • Manual inspections – They are used to verify various aspects of the printed circuit board assembly process.
  • Automated Optical Inspection – It can be used to check issues such as:
    • Shorts
    • Any violations in spacing
    • Drilled hole breakout
    • Solder Paste Application
    • Location and orientation of components
  • X-Ray Inspection – X-Ray inspection can be used to examine components such as BGAs for solder defects.

Some of the systems that can undertake functional testing include:

  • Flying Probe Test: It can detect improper solder connections as also include some limited functional testing.
  • In-Circuit Test (ICT): This system works fast as also runs sophisticated functional tests. However, it isn’t used for low volume production as it is time-consuming and expensive.
  • CableScan: This relies on connectors as opposed to test points. It can search for assembly issues such as improper solder connections while also running functional test signals

Collaborating with the experienced PCB manufacturer

Collaborating early in the PCB design stage with the manufacturer is a great way to ensure the comprehensive testability of the board. With many PCB designs being put on hold before manufacturing, this is a great way to improve turnaround time. It’s important to check that the board complies with the manufacturer’s DFM recommendations and testing capabilities.

It is also important to evaluate that the PCB manufacturer offers the following services:

  • They have experienced test engineers that can develop hardware and software for functional testing, as also test fixtures and structures.
  • They have sophisticated testing equipment for a wide variety of testing such as flying probe tests, ICT and manual testing procedures.
  • They have existing relationships with component manufacturers.
  • They thoroughly document testing results.

To Sum Up

Clearly then, the abilities of the local electronics contract manufacturer are imperative to the success of the circuit board build. Done correctly, PCB functional testing is the most comprehensive testing regimen for determining whether a manufactured board is reliable for your purpose or not. Functional testing is integral to eliminating any errors that may crop up during the production phase, while also helping to reduce cost.

TechnoTronix is an ISO 9001:2015 certified company who delivers one-stop PCB manufacturing services with specialized support, reliable testing, and multi-functional features. Our consistent quality and quick turnaround time captivate us to our customers, who look on us as a one-stop-shop for all their PCB requirements.

If you have any requirements regarding our PCB manufacturing or need urgent assistance, contact us at [email protected] or call us on 714/630-9200.

Top things you need to know about the Rigid-Flex PCB Manufacturing Process!

By | Date posted: | Last updated: February 15, 2023
Rigid Flex PCB Manufacturing Process

Rigid-flex PCBs are extremely popular as they combine the characteristics of rigid as well as flexible PCBs. Essentially, they layer flexible circuit substrates inside rigid circuit board materials. What it offers, therefore, is the stability and strength of rigid PCBs along with the versatility of flexible circuits. The combination of rigid-flex PCB manufacturing opens a wide range of possibilities when it comes to complex and challenging designs. What it also offers is improved service reliability and performance.

Rigid-Flex circuit boards find wide use in commercial and industrial applications including but not limited to:

  • Military
  • Aerospace
  • Digital Cameras
  • Cell Phones
  • Pacemakers
  • Barcode scanners and more

Advantages of Rigid-Flex PCBs

Some of the specific advantages that rigid-flex PCBs offer include:

  • Stability – With their structure comprising of interchanging layers of rigid and flexible PCBs they offer mechanical stability. They also lend themselves to easy installation in small spaces.
  • Reliability of connections – Rigid-flex PCBs offer increased stability as well as polarity. This leads to reliable connections.
  • Cost effectiveness – Rigid-flex PCBs are extremely cost-effective and ensure that your project is viable.
  • High-density applications – With miniaturization and high-density applications growing in popularity so is the use of rigid-flex PCBs.
  • High shock and vibration resistance – Rigid flex PCBs are resistant to shock and vibration and find a place in a wide variety of applications.

Rigid-Flex PCB Design Guidelines

While the advantages of rigid-flex PCBs are well-documented, there are several design guidelines that need to be followed when it comes to manufacturing these PCBs. These include:

1. Determine The Number of Layers

Rigid-flex PCBs are made of alternating layers of flexible and rigid PCB Material. It is therefore important to figure out the exact layer count that is required. It is prudent to consult your electronics contract manufacturer early to ensure that all the requirements can be met.

2. Heat Sinking

Due importance needs to be given to having a heat dissipation mechanism in place. In the absence of it, the device performance can be impacted, and it may also result in damage to the device. The PCB needs to facilitate heat sinking.

3. Material Layup

Layup of materials is yet another crucial factor. This includes checking for:

  • The UL flammability rating
  • Minimum bend radii needed
  • RoHS certification
  • Impedance control
  • Mechanical considerations, and more.

Material layup, in turn, impacts both cost as well as manufacturability.

Steps Involved in Rigid-Flex PCB Manufacturing Process

The rigid-flex PCB manufacturing process involves the following steps:

Base Preparation

This involves preparation of the laminate. The laminate, in turn, features a copper layer. If the copper contains anti-tarnish, it needs to be removed by immersing it in acid solution.

Circuit Patterns / Structure

Through a process of either photo imaging or screen printing, circuit patterns are generated.

Circuit Pattern Etching

Etching the circuit pattern is largely done by spraying a solution over the circuit pattern or dipping the laminate in an etching solution. Etching is then undertaken on both sides of the circuit pattern.

Drilling Holes

Holes are next drilled using lasers. Laser drilling, in turn, assures precision as well as minimizes waste.

Through-hole Plating

Copper is deposited into the drilled holes and plated with a chemical. This step is crucial to create electrical interconnections.

Coating Etch-Resist and stripping

This step involves applying a photosensitive etch-resist coating on the substrate. The chemical resist applied to the plated through-hole is next stripped.

Cover lay Application

A cover lay is applied to the PCB to protect it from harsh environmental conditions. The coverlay material is screen printed onto the surface of the circuit board and exposed to UV.

Cutting the Flex

The individual flex board is now cut from the production panel with extreme caution and precision.

Lamination

In this step, the flexible printed circuit boards is laminated between the rigid sections.

Electrical Testing and Verification

Electrical testing and verification are the final step that ensures circuit performance and quality.

With the above steps you can rest assured that you will get a performance-driven rigid-flex PCB. The important bit is to choose a contract manufacturer that specializes in the fabrication of rigid-flex PCBs, who can understand your bespoke requirements and deliver accordingly.

As a leading rigid-flex PCB manufacturer, we are fully equipped to handle your PCB manufacturing requirements. With over 4 decades of experience in rigid-flex PCB manufacturing as well as assembling PCBs with differing levels of complexities, our team of experts & state-of-the-art equipment ensures that all our PCBs meet the industry standards of quality.

In case if you have any questions or queries regarding our rigid-flex PCB manufacturing services, please feel free to contact us via email at [email protected] or call us at 714/630-9200.

Everything you Need to Know About PCB V-Scoring!

By | Date posted: | Last updated: January 6, 2022
PCB V-Scoring

PCB V-scoring is a form of PCB panelization that allows you to both fit multiple PCBs onto a single manufactured board and allows you to separate the boards after assembly. It derives its name from the fact that it involves cutting a “V” shaped groove at the top and bottom of the PCB.

In order to V-score a PCB, what is required is a specialized scoring tool with a top and bottom blade.

The Requirement for PCB V-scoring

V-scoring is required to make the printed circuit board assembly process efficient. The process of V-scoring ensures that the assembled boards can be separated using minimal pressure.

Importantly, V-scoring helps with the following:

  • Making efficient use of the board space.
  • Reducing manufacturing cost by making several PCBs on one board. It also helps with putting two or more related circuits on the same assembly that aids in efficient sub-assembly. Depaneling machines are also relatively inexpensive. Besides, they are portable and not high on maintenance.
  • Saves time as you can easily separate parts from a completed assembly. The process of V-scoring allows you to put components on each section of the board in a single run. Later you can simply separate the boards making the PCB assembly process both cost as well as time-efficient.

Challenges of PCB V-Scoring

  • V- scoring is restrictive in terms of panel design. V-groove isn’t the best option for designs where the components are too close to the edge.
  • It also necessitates a clearance of 0.05 inches between the components and V-grooves. Tall components, particularly, must be placed away so that the cutter doesn’t come in their way. Similarly, components with large connection areas should also be placed away from the groove.
  • V-grooves can impact the structural integrity of the PCB leading to warpage or being caught in the wave-solder machine. Adding jump scoring to the leading and trailing edges of the array, help to strengthen it.

How do you specify PCB V-Scoring?

The PCB V-score can be specified based on the depth of the score or looking at the cross-section.

The standard way to specify the V-score is to cut 1/3rd on top, 1/3rd at the bottom, leaving 1/3rd of the web in the middle. Manufacturers are known to offer a 90 degree and 30 degree score as well. While the ninety-degree score is known to break easier than a 30-degree score, it takes more space on the layout.

General Rules for PCB V-Scoring

The general rules of the thumb for effective PCB V-scoring are as below:

  • The spacing between the boards should be 0 mm.
  • The minimum PCB footprint size for V-scoring is 75mm x 75mm, and the maximum size is 450mm x 1245mm.
  • V-scoring should go straight across the whole board, although floating vertical and horizontal lines are also possible.
  • Spacing between the V-scoring line and the outline of the PCB should be at least 0.35mm.
  • The board thickness of a V-scored board should be at least 0.6mm.

PCB V-SCORE VS. TAB ROUTING PCB PANELS

The choice of V-scoring versus tab routing largely depends on the PCB design. The following factors would come in handy in making the right choice:

  • Shape of the board – V-scoring works well for square or rectangular boards while tab routing lends itself to unusual shapes.
  • Edge components – For edge-hanging components, tab-routing is a far more workable option.
  • Edge Quality – V-scoring results in rough edges. If edge quality is of importance, once again tab-routing will be preferable.
  • Time – Tab routing takes more time and labor to set up. V-scoring, on the other hand, is far quicker.
  • Waste material – V-scoring tends to waste far less material than tab-routing and is therefore more cost effective.

To Sum Up

PCB V-scoring is a major source of cost advantage to electronics manufacturers. It takes away the need for the space needed for routing and therefore offers the ability to add an increased number of rows to the fabrication panel. Wasted laminate is thereby eliminated. Not only does V-scoring save money but also time, as it streamlines the fabrication and processing method.

Technotronix is one of the leading PCB manufacturers in the USA. We have over 4 decades of experience in providing innovative PCB manufacturing services using modern technologies & the latest machinery. We are adhering to strict high-quality standards and compliant with the RoHS (Restrictions of Hazardous Substance) directives. We can fulfil the varied needs of our customers from the simple board to the most complex board for PCB prototype to production. For more information, contact us via email at [email protected] or call us on 714/630-9200.