How does PCB Inspection play an important role in PCB assembly process?

By | Date posted: | Last updated: February 8, 2022
PCB Inspection

The printed circuit board assembly process isn’t complete until a robust inspection process is concluded. Its ability to point out hidden defects cannot be overstated. That it saves you precious time and protects you from costly errors at a later date is a given.

Here are some of the common PCB inspection processes that are often undertaken:

  • Manual PCB inspection: As the name implies, it involves manually looking at assemblies to inspect them for problems.
  • AOI PCB inspection: Automatic or automated optical inspection involves using an optical system that takes an image of the PCB assembly and to identify any flaws.
  • AXI PCB inspection: With density of PCBs increasing not all solder joints may be visible. Optical inspection therefore may not serve the purpose. In such cases an X-Ray system – AXI, is able to look under the chips to view the solder joints.
  • X-Ray Inspection: X-ray inspection is ideal for more complex boards & provides capabilities that other inspection methods can’t. The X-ray inspection will let you see inside solder joints to reveal bubbles that you can’t see using AOI.

Let us look at some defects that can be easily pointed out using some of these PCB inspection techniques:

Blind or Buried Vias

The use of vias in PCBs has become ubiquitous as they help different layers of the board to be connected easily. The integrity of blind and buried vias, however, cannot be ascertained with visual inspections. X-ray inspection can though send radiations that can penetrate through hidden spots and make it easy to assess the quality of connections as well as components.

Errors in landing patterns

Landing patterns of specific elements on the board often have errors associated with them. For example, if the components used on the board are not included in the library of commonly used SMD components, the chances of having the landing pattern wrong are that much higher.

BGAs

With the use of the Ball Grid Array system, components are packed with high density on the board. In this case also a PCB X-ray machine comes in handy to check the quality of components as well as board connections. The images generated from the PCB X-Rays can go a long way in seeing individual components and identify any flaws.

Decoupling Capacitors

Decoupling Capacitors help in ensuring stability of power supply as also removing oscillations and transients. Wrong placement of capacitors can however lead to suboptimal performance of the device. An inspection process ensures easy identification of any erroneous placement and correction.

Solder Voids

Soldering plays a very important role in connecting the component to the board. Any error in soldering leads to faulty connections and will impact the integrity of the PCB.

Inspection is therefore imperative to look for solder voids that can lead to low quality connections. In turn, it ensures that poor quality connections can be avoided.

Pin-Hole Fills

Through-hole is an important technique of connecting components to the PCB. However, it is prone to several defects including pin-hole fills. Essentially, they occur on account of escaping of gas while soldering. If the heat of soldering is excessive, it will lead to continuous escape of gas. During a quality assessment the pin-hole fills can be identified and integrity of soldering, ascertained.

To Sum Up

PCB Inspection comes with a wide range of benefits and ensures quality control of PCB. In fact, inspection of PCBs can help improve the overall PCB production process. If a particular defect tends to occur repeatedly, you can correct the flaw at the process level itself. Looked at in this manner, PCB inspection plays an important role in the continuous improvement of the PCB production process.

While it may be tempting to look at it like a cost, the fact remains that the cost of failure of products can be far higher, in the absence of inspection. Inspecting PCBs can uncover any defects. In fact, checking PCBs after each phase can help uncover flaws before moving to the next stage. The inspection method can help you ensure consistent quality across boards. Without a proper inspection protocol in place, flawed boards could reach the market. Especially if the defects are found out after the products have been shipped out, you not only may need to deal with expensive recalls, you will also have to face a costly loss in reputation. Worse still, a defective PCB can lead to injury or death, particularly if it is being used in a medical device or an automotive component.

From manual visual inspection to Automated Optical Inspection, X-Ray inspection, PCB functional testing and more, the wide range of inspection techniques ensure adequate performance while maintaining acceptable cycle times. Determining the best techniques for the needs of your project can go a long way in ensuring PCB integrity.

At Technotronix, we are fully equipped to handle your PCB manufacturing requirements. Our team of experts and state-of-the-art equipment ensures that all our PCBs meet the industry standards of quality and testing. It is our vast portfolio of satisfied clients that stand as the biggest testimony to our success. In case if you have any questions, please feel free to contact us via email at sales@technotronix.us or call us on 714/630-9200.

What is electromechanical assembly? What are the factors to consider for designing it?

By | Date posted: | Last updated: February 1, 2022
what-is-electromechanical-assembly

An electromechanical assembly is known to utilize electrical as well as mechanical components when it comes to performing a wide variety of functions, including but not limited to:

  • Generating Power
  • Controlling Systems
  • Conducting mechanical tasks

Electromechanical Assemblies find extensive application in:

  • AC & DC power distribution
  • Control Systems
  • Computer Interfaces

Putting together effective electromagnetic assemblies requires the skills of highly qualified technicians who have the required expertise in a wide range of production skills, from through hole work and surface mounting, to soldering and circuit layout. The involvement of skilled technicians also means that the production times are significantly reduced. Assembly services for electromechanical devices involve a wide range of operations including:

  • Procurement
  • Engineering operation
  • Production operation
  • Robust testing procedures

A significant number of electromechanical assemblies use PCBs that use different tracks to conduct current to components. The tracks are threaded across a substrate. Multi-layer boards often involve the use of vias to connect several layers.

As far as the PCB assembly methods are concerned, there are several assembly methods including:

  • Bench
  • Line
  • Focused Cell Assembly

Factors to be considered in designing electromechanical assembly

When it comes to designing or upgrading electromechanical assembly, the process requires a lot of dexterity and needs you to take several factors into account. These include meeting specific requirements, addressing technical issues as well as taking costs into account.

Here are the primary factors that need to be taken into account in designing or upgrading your electromechanical assembly:

Upgrade or new design

When it comes to the technology of electromechanical systems, they are in a constant phase of change. It is therefore prudent to evaluate the components for quality. While in some cases upgrading your existing designs can be prudent, in yet others it is more cost-effective to have a new design in place.

Real World Testing for Electromechanical Assembly

An important aspect of electromechanical assembly is its extensive use. In designing the assembly, it is imperative that its usage be taken into account. The system therefore needs to be tested for structural integrity as well as durability. The efficacy of a good design is when it can stand tall in these tests. In the absence of robust testing, you tend to stand the risk of the design failing you at a later stage and leading to costly errors.

Software and Support

When it comes to electromechanical assemblies, the focus has to be on software as much as it is on hardware. You need to make sure that the contract manufacturer has competent engineers that can take care of the software requirements as also provide support. In fact, the ability of the manufacturer to offer support in terms of meeting delivery schedules, parts and services on demand is crucial.

Check for tolerances

It is imperative to make sure that each part has a defined tolerance. It is also important to determine that even in the worst cases of tolerance build-up, everything fits together. The sub-assemblies also need to fit into the final assembly.

Avoid too many parts

An effective way of assessing design is if it has a reduced number of parts. Less number of parts make assembly easier. It will be helpful to determine whether parts can be combined together.

Timely Delivery

With time being of the essence, it is also prudent to check for the fact that the specific parts required will be available within the set timelines. It is ideal that the manufacturing partner monitors all parts using RFID tags or barcodes so that you can rest assured that the assembly is up to speed.

Have enough space

In looking at the final design drawing, it is important to check that there is enough space for the assembly staff to put it together. Space is also of the essence when it comes to servicing.

Involve the PCB Contract Manufacturer Early

It is important to involve the PCB contract manufacturer as early as when the first draft of the design is ready. You also need to have sufficient time to make changes after the prototype.

The above tips can go a long way in designing an effective electromechanical assembly. Getting the process right will help with cost-effective product build, shorter lead times as well as greater reliability.

We are one of the leading PCB manufacturers in the USA. We have over 4 decades of experience in providing innovative Electromechanical assembly 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 sales@technotronix.us or call us on 714/630-9200.

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.