Jun 2, 2020|Product Innovations and Design, Technological Advancements and Materials

Wondering what a double sided PCB is and how you can use it in your designs? Find out now in Candor’s comprehensive guide. In this guide, we’ll tell you what double sided PCB is, how to make one, when to use it, and what the benefits are. 

What is a double sided PCB?

Double sided printed circuit boards (PCBs) are the most popular PCB used today. A double sided PCB, as opposed to a single side, is used in higher technology electronics because they have two-sided traces with a top and bottom layer.

You can imagine a double sided PCB as simply two single sided PCBs on top of one another. This explanation seems obvious when you explain it this way, but the layers involved in a double sided PCB are no more complicated than a single sided PCB, there are just two of them on either side. 

When your PCB is double sided, there are closer and more routing traces available because you can alternate between a top and bottom layer rather than just relying on one layer as you do with a single sided PCB. 

With a double sided PCB board, you can mount copper and other components on both sides of the circuit board, allowing the traces to cross over one another. This allows for a more complex circuit to be built, therefore increasing the utility of the PCB.  

How do you make a double sided PCB?

The construction of a double sided PCB is not too different from a single sided PCB. There are some exceptions, of course, one being that some layers are laminated on both sides of the circuit board. We’ll go through the double sided PCB assembly process below. 

The base of the double sided PCB is made up of an insulating material called substrate. The substrate is mainly fiberglass epoxy resin. The type of base material used is what defines if a PCB board is made of Flexible PCB or Rigid PCB. In double sided PCBs, copper foil is often laminated on both sides of the substrate. 

Solder mask, which helps protect the rest of the PCB, can be found above the copper foil on both sides of the board, and silkscreen can be found above the board’s solder mask. However, the silkscreen is mainly used to add symbols and characters on the outside of the board, so someone looking at it can understand the functions of the board. 

All of the layers that you find in a double sided PCB are also found in a single sided PCB; the only difference is that each layer appears on both sides of the board as opposed to one side, hence the name.

When should you use double sided PCBs?

Because there are many benefits to using double sided PCB, which we’ll go into later, they have a wide variety of electronic applications. The versatility of double sided PCB will allow you to use it on projects like: 

* Industrial controls

* Power supplies

* Converters

* Control relays

* Instrumentation

* Regulators

* UPS systems

* Power conversion


* LED lighting

* Hard drives

* Printers

* Phone systems

* Power monitoring

* Automotive dashboards

* Line reactors

* Test equipment

* Amplifiers

* Traffic systems

* Vending machines

There are uses for double sided PCB beyond what we have listed here, but this non-exhaustive list shows you just how functional double sided PCB can be. 

Anytime you need to save time, money, or increase capability is an excellent time to use double sided PCB. There’s no one project that it’s best suited for because it has so many different applications in the field of technology. However, we’ll go into more detail about the benefits of using double sided PCBs below. 

Benefits of double sided PCBs

We mentioned earlier that double sided PCBs are more useful in creating higher technology electronics because they have two-sided traces instead of one. This provides a lot of benefits for those using double sided PCB in their industry. 

Perhaps one of the most important benefits of using double sided PCB is that they help reduce overall cost. In addition to having a relatively lower price compared to single sided PCB, double sided PCB also provides more flexibility for designers while simultaneously reducing the size of the circuit board itself. Smaller board sizes can also help further reduce cost, which is another plus. 

PCB double sided is also associated with increased circuit density and an intermediate level of circuit complexity. Increased circuit density often helps contribute to lower cost as well, as compared to more complex, multilayer PCBs. 

Double sided PCBs are often a better choice than single sided PCBs because of their complexity. If your circuit board is more densely populated to connect a lot of components, it’s better to have some components connected to the bottom side rather than all on one side. 

If you’re unable to change the size of the board size, and you need to route Vcc and GND on a single board, picking a two-layer board and routing Vcc and GND to the bottom layer will help you out. 

If you intend to sink or source current, choosing double sided PCB will most likely make more sense because of the top and bottom layer. You can use the bottom layer as a ground copper pour. For all of these reasons, double sided PCB is often the ideal choice for most professionals working in the technology fields because it’s much easier to use and is much more flexible when you do use it.

Drawbacks of Double-Sided PCBs

Double-sided PCBs have many important benefits, but they are not ideal for every situation.

They do not conduct heavy currents well, as their copper wiring will overheat. This means that manufacturers must remain aware of this issue when utilizing double-sided PCBs, to ensure that all products remain high-quality and don’t sustain damage.

There is also the risk that double-sided PCBs can overheat when they are being soldered. Any PCB experts know this, and those who have manufactured thousands of PCBs understand what steps to take to minimize risk and ensure there are no issues.

Double-sided PCBs can be complex, meaning increased manufacturing costs and labor. Thankfully, any place that regularly manufactures all kinds of PCBs has streamlined this process. PCB assembly for single-sided, double-sided, and multi-layer boards all come with their pros and cons.

Comparison with Other PCB Types

Single-Sided PCBs vs Double-Sided PCBs

There are a few things to keep in mind when comparing single-sided versus double-sided PCBs. Firstly, single-sided PCBs have their components and conductive copper mounted to one side, with the conductive wiring on the other side. Second, double-sided PCBs have their traces on both sides, with top and bottom layers. This makes double-sided PCBs better for high-tech applications, compact electronics, and more complex circuits.

Both single and double-sided PCBs have circuit space restraints and mounting technology requirements, but double-sided PCBs have many advantages that make them attractive to manufacturers. With a conductive copper layer on both sides of the board, double-layer PCBs are more suitable for complex circuit designs. They do have a higher manufacturing cost, and a slower manufacturing speed, meaning that volume production is lower. When production is the chief issue, single-sided PCBs are typically the option, especially since they are more suitable for basic circuit designs at a lower cost.

These days many electronics require circuit boards with more flexibility. Double-sided PCBs are excellent for more demanding applications and higher tech, though they can be difficult to troubleshoot and repair. Double-sided PCBs are used in cell phones, car dashboards, and other technologies that require more complex circuits.

Double-Sided vs Multi-Layer PCBs

Multi-layer PCBs offer functionality beyond the dual-layer design of the double-sided circuit boards. Multi-layer boards consist of three or more layers of conductive material, separated by insulating layers that provide electrical isolation.

These custom PCBs have multiple conductive layers that are interconnected through a complex network of traces and vias. This allows more components and more intricate circuits, accommodating intensive builds.  With enhanced signal integrity, multi-layer boards excel in applications where signal integrity is the most crucial component. The additional layers provide improved shielding, reduced electromagnetic interference, and support highly complex circuit designs. Laptops. smartphones, and computers frequently employ multi-layer PCBs.

Double-sided PCBs are preferred when the circuitry is on the simpler side and space constraints are not as severe. They are less costly than multi-layer PCBs, though multi-layered PCBs are preferred for more compact devices where signal integrity and noise reduction are necessary.

Frequently Asked Questions

How to Connect Two PCB Boards?

Circuit boards can be connected by using different types of circuit board connectors. Most circuit board connectors fall into the categories of flexible or rigid: flexible cables can be used in places where electrical connections require higher flexibility or in multiple PCBs that are subject to vibrations, and rigid cables are used when PCBs are stacked atop one another or side by side.

How to Solder Double-Sided PCBs?

Unless you opt for hand assembly, the board needs to go through sequential reflow soldering. Reflow soldering is used on high-volume runs or low-cost prototyping runs, and designers should plan for reflex soldering during assembly. When double-sided PCBs are soldered, components are placed and soldered individually on each side of the board. It’s important to solder at the right temperature and time so that the first side won’t be reflow soldered twice.

It’s important to be careful when soldering double-sided PCBs as defects can occur. The biggest defect is warpage, though weak and failed solder joints can also occur. Running the soldering process twice on a board increases the risk of defects, which is why this process requires care and experience. Quality manufacturers will take additional steps to prevent these defects, from soldering components by hand to specifically designing the board so that certain components overlap.

Final Thoughts

If you’re interested in a career in technology or if you’re already in the field, PCB, specifically double sided PCB, is something that you’re going to be dealing with a lot. Most of your knowledge about this will come through hands-on experience, but it’s always a good idea to read up on a subject. 

Candor can help you bring your technological vision to life, visit our site to learn more about PCB manufacturing.


Author Profile

Sunny Patel
Sunny Patel is the Engineering and Sales Manager at Candor Industries. Sunny is trained as a IPC-A-600 trainer, AS9100 Lead auditor, IPC CID and got his Engineering degree at the University of Toronto.