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Common PCB Problems Your PCB Manufacturer Should Be Avoiding!

By Mer-Mar Electronics | Date posted: | Last updated: January 20, 2023
common pcb problems

With the PCB being a crucial component that ensures smooth working of an electronic device, maintaining the quality of PCBs is an important task. Any defects can lead to expensive errors & can cost the company and its reputation.

Here are some common PCB problem that manufacturers need to avoid. Needless to mention that experienced, professional manufacturers, have the necessary checks & balances to ensure that the production process is seamless.

Common PCB Problems

1. Acid Traps

As their name suggests, acid traps refer to small pockets of spaces where an etching solution that is used to remove excess copper, gets trapped. These acid traps result in corossion as well as faulty traces. One of the reasons that cause acid traps includes trace bending below 90 degrees.

Some of the validation checks that help control this issue include:

  • Checking for sharp corners that could act as potential traps.
  • Checking for absence of teardrops where a breakout of vias is possible.

2. BGA Spacing

During BGA assembly, BGA components are an essential addition to PCBs, they can cause a number of issues. For example, pads for the ball grid are under the die, or spacing around the BGA pads isn’t proper.

Some of the validation checks in this area include:

  • Ensuring enough clearance space around BGA pads. The through-hole vias need to be positioned at the center of the four BGA pads.

3. Tombstone Effect

As its name suggests, tombstone results when the component is lifted from one end, giving it the appearance of a tombstone. This is largely caused when the wetting isn’t accurate.

Some of the validation checks that help control this issue include:

  • Ensuring that the connected copper at the pads are within the allowed limits.

4. Test Point Existence

A test point is used to test the state of the circuitry. If adequate attention isn’t paid to test points, it leads to a situation where at the manufacturing or the PCB assembly stage, errors are hard to diagnose.

Some of the validation checks that help control this issue include:

  • Ensuring that test points have been incorporated at the design stage.

5. Visual Features

It is important that the overlay layers contain relevant information such as:

  • Reference Names
  • Component outlines, and more

Oftentimes errors occur on account of factors such as reference names of passive components being placed on top of pads or sometimes even under a component.

Some of the validation checks that help control this issue include:

  • Ensuring that the reference names are accurate, as is the order.
  • Checking for the first pin mark for Complex ICs
  • Ensuring that the reference names are placed correctly.

Areas Where Common PCB Manufacturing Defects Arise

Besides these common issues, it is important to broadly remember that manufacturing issues can arise in three broad areas:

1. Material

The manufacturer needs to be aware of the fact that certain materials work for certain circuits. The choice of the wrong material can severely impact signal integrity. Similarly, the operating environment has a lot to do with the choice of material.

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2. Components

In choosing the components several issues need to be kept in mind, including but not limited to the lead time of the components. Choice of components with long lead times can affect the time-to-market & hence competitiveness.

3. Design

Issues with design include aspects such as:

  • Not including fiducials for fine pitch parts
  • Not having enough clearance
  • Components placed too close to each other, and more

The use of robust design for manufacturability practices can go a long way in ensuring that such design issues are avoided. The choice of the right CM is also crucial as they will be best placed to point out any such issues.

It is important to remember that it is only a manufacturer with robust expertise who can take care of these nuances. Such manufacturers are equipped with industry best practices & can ensure that you do not have to reinvent the wheel.

Choosing Mer-Mar Electronics as a contract manufacturer is the first step towards ensuring seamless manufacturing of your PCB, no matter how complex it is. With 40 years of experience & expertise, we are a reliable manufacturer who provides PCB assembly and PCB fabrication service with a quick turnaround time. Fill out the form below to request a free quote now.

common pcb problems

What are the basic requirements for manufacturing circuit boards?

By Mer-Mar Electronics | Date posted: | Last updated: December 2, 2022
Manufacturing Circuit Boards

When you need your contract manufacturer to manufacture high quality circuit boards, it is imperative that basic data requirements are fulfilled. It is this detailed data that can ensure that the boards are crafted to your exact specifications & that there is no dissonance. In addition to the data provided, it is also important to make sure it is given in a mutually acceptable format.

Let us look at the basic requirements for manufacturing circuit boards:

Basic PCB Manufacturing Requirements

1. Sizes of slots & holes

The size of slots and holes is very important in PCB manufacturing.

The size of slots and holes is very important in PCB manufacturing. Slots, in turn, can be of several types, important among them being:

  • Plated Slots
  • non-plated slots
  • Metallic Annular Slots
  • Non-Metallic Annular Slots

It is imperative that all considerations & details be shared so as to create the ideal slots for your PCB.

2. Board outline

This needs to include the dimensions as well as tolerances.

Some of the tolerances that need careful consideration include:

  • Inner layer clearances
  • Copper-to-edge of PCB
  • Thickness tolerances
  • Copper trace width, and more

3. Copper Weight

Finished Copper weights are yet another requirement that impacts production as well as the overall cost. It is also important to balance the copper on the sides. By doing this you tend to save on time, and sometimes also on costs.

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4. Board Thickness

Finished Board Thickness is yet another critical aspect that you need to indicate. The measurement criteria and the tolerances need to be clearly indicated. Also, one aspect that is ignored is that the area where the PCB should be measured for thickness is often not indicated. It is important to indicate whether you want the measurement to be over metal, over mask, over laminate or more.

5. Surface finish

The type of surface finish required is a very important instruction that needs to be given at the outset. In terms of surface finish, you need to indicate whether it should be RoHS compliant. There are a number of popular finishes such as HASL, ENIG, Immersion Silver, OSP, Immersion Tin & more.

6. Solder Mask requirement

Solder mask is yet another thing that needs to be specified. You need to clearly state the color required. While a Gloss Finish is more widely used, you could opt for either Matte or Gloss.

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7. Silkscreen requirements

You also need to state the Silkscreen requirements.

The data to be put includes:

  • Reference designators
  • Component symbols
  • Pin markings
  • Special markings
  • Documentation

Additional Requirement

In addition to the above, in case there are any additional requirements they need to be clearly stated. Such additional requirements may be by way of:

Impedance

Essentially you need to specify the following:

  • Target impedance.
  • Trace width.
  • Trace height.
  • Layer the impedance trace is on.
  • Spacing between copper components.

Vias

The information to include is to do with via structure, whether it is through, blind or buried, via diameter, tolerance and more.

Milling

These could be noted on the fabrication drawings and includes parameters such as smallest radius for inner corners, milling contour & more.

It is also important to specify the array or panel configuration method. It could be scored or tab routed. In addition, the fiducial locations as well as the shapes & sizes need to be specified.

Other than the above aspects, it is important to remember that the fabrication instructions should be provided in a format that can be easily understood. Some of the formats that work well include Gerber, Adobe Acrobat, AutoCAD and more. It is best to check with the contract manufacturer on the formats that work for them, so that no time is lost.

Last, but definitely not least, best practice demands that you specify a technical contact who can be reached out to in case of any queries. This ensures that any time there is any requirement for technical clarification, it can be sought without any delay. This goes a long way in ensuring that there are no delays & that eventual time-to-market is significantly expedited. Needless to mention that since time-to-market is a source of significant competitive advantage in today’s times, its importance cannot be overstated.

Manufacturing Circuit Boards

Digital thread in PCB manufacturing – Improve it with software-based approach!

By Mer-Mar Electronics | Date posted: | Last updated: September 12, 2022
digital thread in manufacturing

PCBs play an extremely key role in developing several modern technologies. Right from wearable devices to space launch systems, everything relies on PCBs! In many of these industries, several of which are mission-critical, speed is of the essence. However, the concept-to-market product lifecycle is long. This means that there could be many weeks before the engineer can have a working prototype in his hands and many more weeks before the final product is made available.

Traditional PCB Design Approach

The traditional design, build and test cycle typically works as follows:

  • Step 1- The engineer creates the design.
  • Step 2- The design is next sent to the manufacturer to build.
  • Step 3- The manufacturer builds it & sends it back to the engineer for testing it.
  • Step 4- The engineer identifies flaws, if any, and it is sent back to the manufacturer for rectification.

The loop repeats and several iterations may be necessary before the engineer is satisfied with the final prototype. The process can take weeks or months. The common causes of delays include:

  • Information sent to the manufacturer is lost or misinterpreted.
  • There are communication errors.
  • Resolution of questions could come with their own set of issues.
  • There is lack of connectivity & the manufacturing process may work in silos. This, of course, not only slows down operations but also keeps the engineer isolated.

One way to overcome these issues, and to accelerate PCBA (Printed Circuit Board Assembly) manufacturing, is to use software-driven automation.

Digital thread in manufacturing – Software PCB design approach

One way to speed up the excruciatingly slow PCBA manufacturing cycle is to leverage software automation. It helps to create a digital thread. In turn, the information flow from the engineer to the factory floor is automated. The engineer, therefore, can communicate directly with the manufacturer through the process of the DBT cycle. Needless to say, this adds both speed & accuracy. The other advantage with this automation is that operations are streamlined as communication no longer remains analog. With IoT devices integrated throughout the operations, various control systems can be monitored. This way data can be gathered & shared & continuous improvements made and the build process optimized.

What is digital thread?

The digital thread in PCB manufacturing provides the ability of access, transformation, integration, and analyzing data from systems to product lifecycle. It includes a communication framework which helps in streamlining an integrated view and data flow of products through its lifecycle.

To put it simply, Digital thread manufacturing does not rely on a physical connection between various stakeholders. Instead, there is a digital communication network, which connects various systems as well as users. Digital thread manufacturing, therefore, uses digital means of communication to link the manufacturing processes, principles & equipment.

In turn, this lends itself to real-time monitoring & control of the product throughout the manufacturing process. The big advantage here is that people may be spread across various geographical locations and there could be many diverse types of equipment.

Key advantages of digital thread manufacturing

Digital Thread Manufacturing offers a wide range of benefits, that include but are not limited to:

  • It allows for full process control, by virtue of which potential issues can be easily identified. Importantly it also helps improve yields.
  • You can monitor the real time process and therefore streamline operations. It also minimizes downtime as well as any potential delays.
  • It is understood that it facilitates transparent communication and helps with white-box manufacturing.
  • It facilitates agile manufacturing and hence it helps make changes quickly without any loss of quality. Also, it helps with data & information exchange.
  • It is highly cost-effective as the costs for data processing and storage are significantly reduced with the use of clouds. Importantly, there is a lot of cost saving as it helps you to identify and mitigate risks early on.
  • This ensures you do not have to contend with costly errors later in the cycle. Also, it helps respond to design changes quickly, thereby it saves time & also ensures that there is minimal wastage.

To sum up

The traditional prototyping process acts as a bottleneck when it comes to speedy product development. It also inhibits the engineers’ ability to innovate. With software automation and IoT networks, many of these issues that plague traditional manufacturing are solved. It works far better in terms of both quality and cost.

Mer-Mar Electronics provides a full range of PCB manufacturing services including PCB assembly, PCB fabrication, and prototyping services. We provide service according to your requirements.

Fill out the form below to request a quote or contact us at sales@mermarinc.com or call us at (760) 244-6149.

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PCB manufacturing tolerances and its impact on fabrication and assembly process!

By Mer-Mar Electronics | Date posted: | Last updated: August 22, 2022
PCB manufacturing tolerances

It is imperative that when you offer the documentation for PCB manufacturing, all the requisite details are provided. Very often there are missing details that, if provided, can go a long way in quoting the right cost as well as manufacturing PCBs that match up to your bespoke requirements. Robust data needs to include tolerances as they will ensure there are no defaults in manufacturing as well as no production delays. Let us look at these tolerances in some detail:

Important PCB Tolerances

1. PCB Component Tolerances

When it comes to components, tolerance refers to the acceptable variant to be able to ensure proper functioning. Tolerance in this case also refers to the difference in between the lower & upper dimensions of the component parameters.

The overall functionality of the PCB is dependent on how the components perform with each other and therefore it is important to know the limit of each component. Component tolerance modeling is thus a crucial step that ensures reliability testing of the board to determine if the board components succeed in performing as a unit. In fact component tolerance modeling allows the quantification of how individual components relate to the output. The more accurate the tolerance, the more reliable the final product will be. Component tolerance modeling, therefore is an important function of the design as well as the manufacturing process.

What is important to remember is also that since each component brings its own component limit, what needs to be considered is the tolerance stack-up or what is the additive effect of various component tolerances. The tolerance stack-up estimates the effects of the accrued variations & is defined on an engineering design.

2. PCB Material Tolerances

When it comes to PCB laminate materials, it is important to provide specific Tg ratings. Additionally providing a stack-up with specific dielectrics is important. What you also need to provide so that the right material can be selected is the overall printed circuit board thickness. What is needed here is a certain material tolerance since it will be impossible to meet the exact details. If your requirement is for a tolerance less than 10 percent, you might need a change in the core as well as a tighter process control. In turn this will lead to added costs. Materials & cores therefore need to be correctly chosen at the prototype stage as if this is done at the production stage, it can prove to be far more costly.

3. PCB Drill Tolerances

What is also needed when creating a fabrication document is the need to look at PCB manufacturing tolerances to avoid PCB fabrication errors.

For example, plated and non-plated holes need to come with different tolerances as drills cater to specific sizes with strict tolerance. It is important to remember that there are many factors that affect the size of the hole. Some of these include:

  • Plating baths
  • Time in & out of the tanks
  • Additional plating
  • Etching
  • Finished Plating

The need for tolerances is therefore a given. However it is important to remember that not all drills are exact, so some amount of tolerance is required. Where tighter tolerances are required, it is imperative that they should be noted clearly.

In fact, larger holes, plated or non-plated above the size of 0.200”, will require a tolerance of +\-0.005”.

4. PCB Routing Tolerances

When it comes to routing, tolerances are required right from slotting tools to routing cutoffs. Typically, a tolerance of +\-0.005” is the default standard on the size or cut.

Other standard PCB tolerance that you should know

Following is the analysis of outer layer (width annular ring, min annular ring, NP to copper, KO to copper, etc.):

Outer copper thickness 1OZ 2OZ 3OZ 4OZ
Compensation value 0.01mm 0.02mm 0.03mm 0.04mm
Normal trace/spacing 0.12MM 0.15MM 0.2MM 0.25MM
Normal Width between pads 0.12MM 0.15MM 0.2MM 0.25MM
Normal Width between pad and trace 0.12MM 0.15MM 0.2MM 0.25MM

Normal Width between pad or tarce and copper area

 0.2MM 0.2MM 0.2MM 0.2MM
Normal VIA pad single side width 0.15mm 0.16mm 0.17mm 0.18mm
Normal PTH pad single side width 0.2mm 0.21mm 0.22mm 0.23mm
Normal Width between NP   holes and copper 0.2mm 0.2mm 0.2mm 0.2mm

Normal Width between profile and copper

 0.3mm 0.3mm 0.3mm 0.3mm
Normal width between via and copper 0.2mm 0.2mm 0.2mm 0.2mm
Max trace/spacing 0.1MM 0.13MM 0.18MM 0.23MM
Max width between pads 0.1MM 0.13MM 0.18MM 0.23MM
Max width between pad and trace 0.1MM 0.13MM 0.18MM 0.23MM
Max width between pad or trace and copper area 0.18MM 0.18MM 0.18MM 0.18MM
Min width between NP holes and copper 0.15mm 0.15mm 0.15mm 0.15mm
Min Width between profile and copper 0.25mm 0.25mm 0.25mm 0.25mm
Min width between V-Cutline and copper 0.35mm 0.35mm 0.35mm 0.35mm
Min width between via and copper 0.18mm 0.18mm 0.18mm 0.18mm

To sum up

Tolerance modeling is a wonderful way to achieve a balance between performance & cost as otherwise the less the tolerance, the more the cost of production. Tolerance modeling therefore is the key aspect that reduces manufacturing cost while ensuring that the quality is maintained.

Of course, in case you do not specify the details in the manufacturing document, the contract manufacturer will refer to the IPC standards & performance specifications as a guide. However detailed information on aspects such as surface finish copper weights, material, hole sizes and more can go a long way in ensuring that the final product matches your bespoke needs.

One of the top PCB manufacturing firms, Mer-Mar Electronics offers complete packages for PCB assembly. Customers appreciate our reliable quality and quick turnaround, seeing us as a one-stop shop for all their PCB manufacturing needs.

Please do not hesitate to contact our team if you have any questions about our PCB assembly and PCB manufacturing service, or if you require immediate assistance. Send us an email at sales@mermarinc.com or give us a call at (760) 244-6149 with any questions you may have.

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