Current passes through printed circuit boards along their copper layers. Therefore, when you begin your stack-ups, the consideration of the factors revolves not only around PCB dielectric thickness or board thickness. It also includes the copper thickness.

        

That is not a trivial factor to avoid.

               

Choosing the wrong material thickness may cripple the performance of circuits. However, discernmenting the relationship between copper weight and signal transmission is essential.

          

If you are about to venture outside the standard values of design, keep reading this article. This information will provide insight into the copper thickness and its importance.

            

What is PCB Copper Thickness?

          

Manufacturers employ a standard thickness of copper material, usually 0.5 oz/sq ft or 1.0 oz/sq ft, in PCB production. This copper weight to thickness is generally referred to as ounces.

 

Each copper substance has a specific weight. That is evenly spread and pressed flat over the surfaces of an area of 1 square foot. The final result of the copper foil thickness will be 1.37 mil or 0.0348 mm.

         

The metalworkers generally produce copper thickness around 1 oz. However, this thickness can be substituted depending on the project requirements.

         

The 1 oz thickness of copper is sufficient for producing PCB. The increase cripples the fabrication process or escalates the cost of production and cycle time.

         

Despite this, the engineers prefer to increase the width of the copper traces. That improves the efficacy of the electric transmission.

            

Common PCB Copper Thickness

·   0.5 oz copper

·   1 oz. copper

·   2 oz. copper

0.5 oz copper

            

The 0.5-oz copper thickness is usually located on the internal surfaces of the PCBs. It is part of non-standard construction. The manufacturer applies this layer if requested. This is also addressed as the standard starting copper weight. That works for the brittle layer of PCBs with a 1-ounce finished copper weight selection.

            

1 oz copper

            

The 1 oz copper proportions are the standard internal layer for definitive construction applications. That works for 1-2 oz finished copper weight selection. This is correspondingly the standard starting copper weight on the external surface of PCBs. That includes a 2 oz finished copper weight selection.

            

2 oz. copper

            

The 2 oz is the standard intramural layer of copper thickness. These are the internal layers on the finished 3 oz copper. Additionally, 2 oz is the initial standard thickness on the outer of PCB boards.

            

Copper Thickness and Weight Conversion for PCBs

            

Conversion coefficients:

·   1 ounces = 28.35 g

·   1 ft = 30.48 cm

·   1 ft² = 0.093 m² = 930 cm²

·   Copper Density = 8.9 g/cm³

         

Why is PCB Copper Thickness Important?

       

Manufacturers can commonly substitute the thickness of copper beside the dimensions of printed circuit boards. Copper weight drastically can induce changes in other traits of boards.

       

The thickness of copper traces or their layers contributes to weighing the current-carrying capacity of PCBs. That can be somewhat determined by learning the thickness properties of copper.

           

Additionally, the width of copper traces is pivotal. That helps in consideration of the thickness suitability for impedance-controlled boards.

        

Besides this, there are multiple facets to consider in stack-ups. That encloses the weight of the PCB, connector types, and segment compatibility provisions.

            

Why Use Heavy Copper?

            

Usually, 1 oz copper thickness to 3 oz copper is employed in the assembly of PCB boards. Although, there is no suitable definition for heavy copper.

      

Normally, the heavy copper ranges from 2 oz copper-thickness to 20 oz. Likewise, the intense ones range from 24 oz to 200 oz. Customarily, manufacturers leverage heavy copper for the following causes:

·   To fabricate the product compact. Because the circuit boards house several copper weights on the same layers.

·   To support larger current-carrying applications.

·   To reduce overheating and damage during stressful thermal conductivity.

·   To improve the thermal oversight.

·   To pass higher current flow from one layer to another while transferring heat to an outer layer.

·   To make high-power density planner transmission on the PCB

·   To provide high mechanical strength for heavy connectors and through-hole components.

                

Varying Copper Thickness in PCB Layers

            

The personnel often produce the PCB layers, applying the varied copper thicknesses. In the case of the underlying layers, they utilize 1 oz copper. Analogously, 4 oz copper is harnessed for the exterior layers of the boards.

       

During the operation stage, PCB can generate excessive heat. That can bend or damage the PCB board. Manufacturers can reduce this risk. They employ the same copper weight in opposing layers.

           

Copper thickness enables the boards to resist frequent exposure to undue current flow. They facilitate making the task safe even under recurring thermal cycling.

       

Moreover, heavy copper boards can withstand applications in critical situations. They are advantageous for producing outcomes for the aerospace and defense divisions.

            

How To Select The Right PCB Copper Thickness?

         

Trace width, signal transmission, and voltage drop are crucial facets to contemplate while calculating the copper weight. Opt for thicker copper weight if your boards are carrying a high current. This will ensure your copper traces do not produce excessive heat.

        

Accordingly, the thinner copper weight should be implemented to reduce the inductance of the layers. This will cater to maintaining the attribute of high signal integrity.

              

Additionally, heavy copper weights are sought for their ability to handle high current loads. They comprise a thickness range from 3 oz to above. It confers noteworthy thermal management.

            

Design Considerations for Heavy Copper

        

·   Higher Minimum Track Spacing requirements

·   Developed Through Size

·   The greater thickness of the solder mask

               

Higher Minimum Track Spacing requirements

            

Whenever the weight of copper thickness is increased, more spaces between copper features are required.

             

Notably, track spacing is consequential for various copper weights. This step aims to reduce the chances of signal degradation and overheating.

              

Developed Through Size

            

Integrated circuits are usually produced of heavy copper. These are subject to handling higher-current transmission. Therefore, ensure the vias can carry the required current ratio. It should eliminate the excess resistive losses.

          

In conjunction, the larger vias control lower impedance paths for the flow of electric charge. They reduce the resistive heating and minimize the voltage drops.

             

Therefore, appraise the design choice founded on the vias. That can effectively carry the higher current loads. It can maintain steadfast connections, depending on the different layers of the PCB.

            

The Greater Thickness of the Solder Mask

            

Sometimes, the solder mask Origin has difficulties adhering to the copper facings. Owing to the heavy copper having a higher surface tension.

              

The inappropriate fixation of solder masks can peel away from the PCB panels. It will culminate in the exposed copper plates. This could precipitate the shorts, corrosion, and other inevitable issues.

               

You can amplify the solder mask thickness to avoid these predicaments. That will equip more surface area for the solder mask molecules to adhere to.

            

How to Measure Copper Thickness?

        

There are several techniques to put into operation. That can effectively measure the thickness of copper traces. The operators can choose suitable methods for pivoting on their stacks.

     

       

Micrometer

            

A micrometer is widely operated to gauge the stratification of copper material. It is feasible to situate the copper on the surface. Place the metal in the interstice of its anvil and spindle. Then, the meter will compute the thickness of the copper film and show the exact reading.

            

Caliper

            

A caliper is another way to measure copper thickness. Make sure the preexisting reading becomes zero. Then, place the copper and measure its thickness at several points for accuracy.

            

Ultrasonic Thickness Gauge

            

The ultrasonic gauges are subject to calculating the identical thickness of copper. This scenario devotes the non-destructive testing attributes. In this technique, the waves travel through the material surface and figure out the thickness. It counts the time that it takes for the waves to return.

            

X-ray Fluorescence

            

This technique supports determining the weight of copper. These X-ray sources excite the material. They measure the rays transmitted from the substances.

            

Eddy Current Calculation

            

This technology aspires to measure conductive coatings that enclose copper. It induces the eddy currents in the material. That contributes to gauging the substance's thickness.

            

Weight Measurement Applications

            

The weight measurement application is also an effective way to occupy the thickness calculation. This application can be deployed to measure large areas. That integrates a density of copper of around 8.96 g/cm2.

            

Optical Techniques

            

To measure the thin layers of copper thickness, techniques like interferometry are optimal. They generate light interference patterns on the surfaces. It delivers accurate computation of thickness.

            

            

Conclusion:

            

The thickness of copper is as important a factor as its other parameters while weighing the material for your project requirements. It is gauged in ounces. The substitute in their thickness gauge can dissemble the performance of electronic circuit assemblies during functioning. The detachment of higher copper thickness with standard PCB thickness can be executed