Ensure Maximum PCB ESD Protection for Electronics Assembly!

By | Date posted: | Last updated: January 17, 2022
PCB ESD protection

Electrostatic Discharge or ESD as it is popularly known as, occurs when the surface of an object builds up an abundance of electrons. In turn, this creates a voltage potential. When such an object comes in contact with another object that has a lower voltage potential there is a jump of charge, which is experienced as a small electric shock.

In day-to-day life we have all experienced ESD when we have touched a metal object or even while accidently brushing past someone. While we may not pay too much attention to it, the fact remains that ESD can prove to be devastating for electronic components. Especially with miniaturization, as circuits get smaller and more compact, the susceptibility to ESD goes up. The ESD Association has estimated that as many as 25% of electronics that are damaged for unknown reasons could have ESD as the root cause. In fact, ESD is estimated to cost the electronics industry a whopping $5 billion a year.

If PCB ESD protection is disregarded during the electronic assembly process, you could be staring at the following:

  • Component failure on PCB
  • Circuitry damage
  • Increased cost of production
  • Loss of customer confidence

PCB ESD Protection Strategies

When it comes to offering maximum ESD protection for electronic assemblies, there are three levels of protection that are recommended. These include:

  • Facility ESD protection zones.
  • Built-In ESD protection for circuits.
  • ESD-Controlled circuit board storage and transportation.

Let us look at each of these in detail.

Facility ESD Protection Zones

Electrostatic Discharge protected areas go a long way in safeguarding electronics. This is essentially done by grounding conductive materials and workers in ESD-susceptible production areas.

Some of the best practices in this regard use a combination of measures as below:

  • Wearing anti-static wrist straps or heel straps. This is an easy way to dissipate static from people. The straps can be connected to a grounded line.
  • Using conductive floor mats. These mats are helpful in discharging any static that has built up on equipment or footwear.
  • Use of anti-static clothing and shoe coverings.
  • Temperature and humidity maintenance. Essentially humidity is maintained between 40-70 percent on the production floor. High humidity prevents static from building up. However, care needs to be taken to see that humidity isn’t excessive as that can impact moisture-sensitive parts. Temperature is ideally maintained between 22-18°C.
  • Connecting racks and equipment to the ground. People are required to discharge themselves before they enter sensitive areas.
  • Removing sources of static. This involves limiting insulating material such as paper, wood and plastics in sensitive areas.
  • Periodic inspections. It is imperative that ESD levels are monitored periodically and adherence of all guidelines by employees is undertaken. In fact, regular training sessions are the need of the hour so as to sensitize employees, both existing and new.

Built-In ESD Protection for Circuits

This kind of protection is imperative as it reduces the risk of circuit failure or damage during the PCB assembly phase. Some of the practices to follow include:

  • Selecting transient circuit protection device in order to meet the PCB parameters.
  • Ensuring that the suppressor is placed at the point of ESD penetration.

ESD-Controlled Circuit Board Storage and Transportation

It is believed that the risk of ESD is eliminated once the production stage is successfully crossed. The fact however remains that boards also need to be protected during storage as well as transportation.

Some of the best practices to follow at this stage include:

  • Using anti-static packaging material such as anti-static bubble wrap, foam and ESD bags. ESD bags are modeled on Faraday Cage principle and are made with fine layers of metal. They go a long way in sealing its contents from external changes.

To sum up

ESD is an invisible threat that lurks in electronics manufacturing facilities that can have serious consequences. ESD Management practices are effective as they help in the following:

  • Reduce defects.
  • Improve yield.
  • Ensure that the need for re-work is addressed.
  • Improve reliability of the products.
  • Enhance company reputation.

The above three pronged practices can aid in effective ESD management and keep the many issues associated with ESD at bay.

Technotronix offers electronics manufacturing services combining state-of-the-art technology and advanced engineering to deliver unparalleled quality and service. We are upgrading ourselves every day and offering the finest circuit board assembly, circuit board designs and fabrication services to our clients. For more information, contact us via email at sales@technotronix.us or call us on 714/630-9200.

Top Causes of Warpage in PCB Assembly Process & Their Prevention Measures!

By | Date posted: | Last updated: April 8, 2022
Warpage in PCB

With the miniaturization of electronic devices, the use of thin PCB circuit boards and small components is in vogue. However, the use of thin multi-layer PCBs with small SMT components also brings some issues in its wake. Typically, such PCBs suffer from warpage in the PCB assembly process that impacts among other things, its yield. Besides, excessive warpage also leads to the quality of the paste printing being affected. Warpage also affects the formation of solder joints during the reflow soldering process.

Before we get to the solutions that can help control warpage, let us have a quick understanding of what warpage really is.

What is PCB Assembly Warpage?

Typically, all parts of the Printed Circuit Board should be in contact with the surface. However, sometimes on account of various stresses this does not happen. What we have is a condition where some parts of the PCB bend upwards and some downwards resulting in positive and negative curvature. Sometimes the bend may be along the axes of the board or along the diagonals. The board can sometimes also develop a twist. All these are examples of PCB warpage.

Causes of Warpage in PCB Assembly

  • Built in stress on the copper film causes the boards to warp. This is possible even at room temperature without any thermal process.
  • During processes that involve temperature changes, such as reflow, warpage is caused on account of the difference between the coefficient of thermal expansion between the copper layer and the substrate.
  • When individually etched copper clap boards are stacked together, the difference in copper density of each layer causes differing amounts of stress on each layer leading to warpage.
  • PCBs are often placed in a panel so as to improve PCB assembly efficiency. Panelization, in turn, uses rails and outriggers. Post assembly, the outrigger is removed and the PCBs are separated by de-paneling them. The difference in copper density in the board area as opposed to the outrigger area further causes warpage.

Issues Caused due to Warpage in PCB Assembly

  • In case of a warped PCB, some parts of the PCB become closer to the stencil and some parts are further away. In turn, this causes solder paste deposits on the closer part of the PCB to have a lower height. The deposits on the parts with a larger gap have a greater height. With this non-uniform solder paste deposit a number of issues are seen. These include:
    • Stretched joints
    • Open joints
    • Solder bridges
    • Head & Pillow joints
  • When the temperature increases, such as in the process of reflow, its warpage increases. In turn, it can affect soldering under close-pitch ICs.

Ways to Prevent Warpage in PCB Assembly

IPC-A-610E standard specifies maximum warpage for incoming PCBs at room temperatures. As per IPC-TM-650, the maximum bow and twist for an SMT PCB must not exceed 0.75%.

To control warpage in PCB assembly, the following steps are recommended:

  • Copper Balancing – At the design stage itself, due care must be taken to balance copper across all layers. This helps in minimizing the mismatch in terms of the co-efficient of thermal expansion both at room temperatures as also when the temperature increases.
  • Balancing substrates across PCB layers – In a multi layered PCB due attention must be paid to use substrates with different CTEs. It is recommended that substrate of the same thickness and material be used in the top as well as bottom layers.
  • Balancing copper density – During panelization, the difference in copper density in the rails and outrigger areas of the panel needs to be minimized.
  • Pallet Design – It is recommended that the temperature difference between the PCB & pallet is minimized. Also the clearance between the PCB edge and the pallet edge needs to be kept minimal. It is also prudent to use low spring force to hold down the perimeter and corners of the PCB. Providing adequate support to the pallet so that the PCB does not sag at high temperature, is also recommended.
  • Pre-Treatment – It works well to bake the PCB above its Tg. This helps soften the laminates as also relieve the stress in different layers. Warpage is thereby, minimized.

To sum up

It is important to go with a PCB contract manufacturer who has a thorough understanding of the various issues that can cause PCB warpage. The above tips can go a long way in ensuring that warpage is kept at acceptable levels.

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.

The Troubleshooting Guide for Wire Harness and Cable Assembly

By | Date posted: | Last updated: January 18, 2023
wire-harness-and-cable-assembly

While the term cable assembly and wire harness are often used interchangeably, these are two distinct products that have different uses.

A wire harness typically consists of multiple wires within an exterior sheath. The exterior sheath is made up of thermoplastic or thermoset and does not offer too much protection from friction or temperature fluctuation. Wire harnesses, therefore, do not find extensive application in harsh and demanding environments. Cable assemblies, on the other hand, also have multiple wires covered by an external sheath, however the sheath is made up of heavy-duty material that can withstand environmental pressures. Explore the top difference between cable assembly and wire harness.

Below are some of the problems faced in cable assemblies and wire harnesses; and effective troubleshooting methods for them:

Common Problems faced with Wire Harnesses Assemblies:

  • Not making the right choice of cable – Very often the underperformance or failure of the cable assembly is on account of their inappropriate selection given the environment they must function in. For instance, if the cable isn’t durable enough to withstand force, they could break. In such cases, a pull test is required to figure out its strength.
  • Improper Installation – Incorrect installation of cable assembly can impact their performance. Whether it is a sloppy soldering job or if the die is set incorrectly, it is bound to show deterioration.
  • Testing not done correctly – Post assembly of the cable component, if the testing isn’t done correctly, it can lead to issues that can turn out to be costly in the long run.

Common Problems faced with Wire Harnesses:

  • Improper Wire Preparation – Wire Preparation involves stages such as the right selection of wire, cutting it correctly. Any of this not done correctly can lead to incorrectly prepared components.
  • Improper layout – The wires need to be arranged properly so that they fit into the harness.
  • Improper labeling – Especially when harnesses are mass produced, improper labeling can lead to a range of issues.
  • Crimping and defects related to soldering – These can lead to issues related to the circuit.
  • Missing Components- This can lead to harness failure. It is imperative, therefore that the assembly documentation is double-checked.
  • Improper wire tying- Both tying the wires too tightly and tying them loosely can come with its own set of problems.

Intermittent Errors in Cable Assemblies and Wire Harnesses:

Common intermittent errors in cable harnesses and wire assemblies manufacturing process include:

  • Opens
  • Shorts
  • Mis wired

These can be on account of a wide range of issues such as:

  • Poor setup
  • Weak contact
  • Pin not seated correctly
  • Damaged Housing
  • Worn or dirty contacts

Despite all possible efforts undertaken to ensure there are no errors in cable assemblies and wire harnesses, inadvertent errors can still creep in. To avoid this, it is important to test the components thoroughly. Some of the common testing mechanisms include:

Mechanical Testing

This ensures that the mechanical properties are tested to see that they meet the requirement of the application. Some of the mechanical properties to be tested include:

  • Elongation
  • Tensile Strength
  • Flexibility
  • Impact resistance
  • Cycles to failure, and more

Environmental Testing

This primarily involves testing to see that the cable assembly or wire harness can withstand environmental conditions such as:

  • Humidity
  • Temperature
  • Vibration, and more

Electrical Testing

The electrical testing largely involves testing for:

  • Open Wires
  • Incorrect Wiring
  • Risk of shorts

Visual Testing

Visual testing involves looking for all components and ascertaining if they are in good condition. Some of the aspects to watch out for, include:

  • The wires and cables, their placement and whether there is any damage.
  • Whether the connectors are proper.
  • Whether the labeling has been done accurately.

Signal Integrity Testing

This involves assessing the signals that the cable assembly or wire harness can carry. You also need to check for crosstalk and signal errors. Also, it is important to see if the use of connectors, filters etc. ensures that signal strength can be maintained.
A judicious use of both the troubleshooting mechanisms as well as robust testing practices will ensure that you do not face performance issues with cable assemblies and wire harnesses.

Being a leading PCB manufacturer from past over 40 years, Technotronix is providing wire harness and cable assembly services in USA. It ranges from simple to every complex cable and wire harness assembly with quick turnaround time. Technotronix is specialized in layout and assembling of custom and complex cable and wire harness assemblies to address the needs of customers. We cater to the wide spread needs of our broad customer base of varied industries like aerospace, defense, telecommunication, medical etc.

For more information, get a quick wire harness and cable assembly quote or contact us via email at sales@technotronix.us or call us on 714/630-9200.

In-Circuit Test (ICT) vs. Flying Probe Test: Which one is best for your Electronic Board Assembly!

By | Date posted: | Last updated: February 14, 2022
in-circuit-test-vs-flying-probe

When it comes to making a decision about the best testing method for your PCB, they are a number of factors to consider. Some of these include:

  • Costs- both up front as well as per unit
  • Coverage
  • The lead time involved
  • Customization
  • Whether or not it suits the complexity of your design

While both the tests are equally equipped to discover defects such as opens, shots, resistance, capacitance, and component orientation, their differences lie in the following areas:

  • Development Time involved
  • Coverage
  • Costs per unit
  • Custom tooling
  • Engineering charges

Let us take a detailed look at In-circuit vs Flying Probe testing on these criteria as also determine which is most suited for your electronic board assembly.

In-Circuit Testing

The way In-circuit testing or ICT, as it is popularly known works, is that it uses a bed of nails to access the circuit nodes and then check the performance of each component. It can also test the functionality of digital circuits, however, the cost involved there is substantial.

Typically, the strength of ICT lies where you need to test products that are high volume. It is also useful in testing well-developed products. However, since ICT requires that a custom fixture be created, the costs involved as well as the lead times are high. However, the advantage of ICT lies in the fact that once you have the custom tool ready, the per unit costs are low.

If we were to summarize the Pros & Cons of ICT, they would look as under:

Pros

  • It lends itself to quick tests per PCB unit.
  • The per unit costs are low.
  • It can test individual components.
  • It works well when you need to test logic functionality.
  • It can be used to test LED components.
  • You can use it to test BTC component soldering by way of a pressure test.

Cons

  • The lead time involved in development tends to be long, which can be an issue in today’s times where a quick go-to-market is a source of competitive advantage.
  • The high up-front cost can be detrimental in its usage.
  • It requires the use of programming tools.
  • You cannot use it to test either non-electrical components or to test connectors.
  • While it can be used to test individual components, it does not lend itself to testing components working together.

Flying Probe Testing

FPT (Flying Probe Testing) uses both movable and fixed probes to test the top and bottom of your PCB. It uses high-precision needles, which are programmed to undertake electrical and PCB functional tests.

As a thumb rule, Flying Probe Testing works well for low-volume orders. It is also suitable for products that are in the initial stages of development. Since it does not require custom tooling, the costs of FPT, work in an inverse manner as compared to ICT. So, FPT has higher per unit costs as opposed to high up-front costs of ICT.

Let us look at the Pros and Cons of using FPT:

Pros

  • It does not require any custom tooling saving upfront costs and time.
  • You do not have to waste precious time in programming.
  • It is best used to test components individually.
  • It can be used to test LEDs.
  • It has low upfront costs.

Cons

  • The per unit costs are high.
  • It cannot test connectors as well as non-active components.
  • While it can test components individually, it is not suited to test components working together.

Which works better, ICT (In-Circuit Test) or FPT (Flying Probe Test)?

There is no one-size-fits-all when it comes to the choice of ICT or FPT. The choice truly depends upon your individual project requirements. You need to look at factors such as whether you want to go in for low volume or high-volume testing, what kind of lead times you have available, your overall budget as well as the complexity of your PCB design in coming to a well-thought-out decision.

It is important to discuss each of the options with your electronic contract manufacturer. It is imperative that the PCB contract manufacturer you are working with has a complete understanding of each test system and can advise you on which one will work best for your specific needs.

Technotronix is one of the leading printed circuit board manufacturers based in the USA. We have over 4 decades of experience in providing innovative PCB manufacturing services using modern technologies and the latest machinery. We are adhering to strict high-quality standards and compliant with the RoHS (Restrictions of Hazardous Substance). To know more, please contact us.