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Comparison of Metal Film vs. Carbon Film Resistors

Your electronics can literally undergo full failure if their resistors are not performing well. What are resistors? These are a device’s special parts that resist the current flow. 

Thus named resistors. Well, it’s pretty simple to understand them since their name fits fine with their purpose. When a resistor opposes the current, it means it is regulating it at the same time. You will find different types of resistors in the industry. Different producers are relying on these types as per the nature of their projects. 

It is obvious that you need to determine the type of resistor as per your requirements, or else these can ruin your projects straight up! So what are the types of resistors that we are going to review in this post? 

Hang on a second; there is no hurry! Sit back and relax since we are going to discuss all the important aspects of metal and carbon film resistors with you today! Let’s get going!

Definition of Carbon Film Resistors

The basic function of this resistor is the same. It is responsible for resisting the current. However, a carbon resistor does this job by using a carbon film. These resistors are incredible when it comes to enduring intense pulses and frequent transmissions. Therefore, due to these features, these are useful to be a part of electronics like PCs, testing tools, and more. 

Drawbacks of Carbon Film Resistors

2.5K Resistor
  • These are not affordable at all
  • Produces thermal noise when performing
  • It can be less precise in some cases

Definition of Metal Film Resistors

There is no carbon film in these resistors. Instead, the function of these resistors directly depends on metal films. There are different features of metal film resistors that make them a crucial component of several electronics used in daily life. These are more reliable than the carbon film resistors, and the possible reasons are:

  • These are affordable
  • These have small sizes
  • These have less tolerance
  • These produce no thermal noise
  • These are more versatile than carbon film resistors 

The drawback of Metal Film Resistors

  • The power rating of metal film carbon resistors is extremely less

Brief Introduction to Resistors

Simply put, resistors are for resisting the current in a system. It can also re-route the current path, making it change its original one. Also, resistors are beneficial for the regulation of the current so that you can give sufficient current to your system. 

In the case of higher and lower currents, the system can collapse and fail to function properly. You can take advantage of resistors by aligning them in parallel and series circuits. However, this depends on your project as well. You can even use a resistor for monitoring and stopping voltage. These are completely sourceless, which makes handling them much easier. When the current goes through a resistor, it will dissipate heat. It means there will be a definite loss of power. 

Resistors work on the ohm’s low, and due to this reason, these are behind the efficient performance of devices that you use almost every day in your life. There is a wide range of varieties that you will find in resistors. You can divide them into different factors like their composition, films, and wiring. Now its time to check the factors that greatly influence the working of resistors:

  • Reliability
  • Thermal noise
  • Size
  • Voltage
  • Temperature

In the further sections, we are going to take an extensive look at the carbon film resistors. So that you can understand their function completely through our discussion, you will also get to compare them with metal oxide film resistors. We are affirmative that there will be no confusion left for you regarding carbon film resistors. So let’s crush it!

Carbon Film Resistor


The design of these resistors mainly depends on a carbon film. This special covering is present on an insulative substrate or a ceramic substance. It is a thin layer, and you might even have to use a microscope to see this layer precisely. Now you can compile this entire process under a single word called sputtering to save you time. When the film fully takes over the substrate, it will resist the current. Pretty obvious since this is what a resistor is supposed to do!

Why are we using an insulative ceramic material in this setup? Well, it is because of the heat. The ceramic substance will trap the heat from going out and enables the resistor to endure extremely high temperatures. These temperatures never ruin the resistor because of this little component – a ceramic substance. When you need to observe and work with the tolerance, you can fully rely on carbon film resistors. These have a negative resistance which will reduce as you will enhance the temperature. 

Metal Film Resistor

Some resistors come with a metal oxide film which imparts different properties in them as compared to the carbon film resistors. Similar to carbon resistors, the metal oxide layer will cover the ceramic substance instead of the carbon film. The oxide layer fully adheres to the ceramic substance.

Now if you use antimony oxide for this purpose, it will be just icing on the cake. It has remarkable properties that will enhance the quality of your projects on the whole. Just like carbon film resistors, these offer impressive endurance for high temperatures. It is because we are using a ceramic substance that traps heat, just like carbon film resistors. The trick to using metal oxide for this purpose is that it will stop the current to a large extent. It means the metal layer you are using for this resistor can greatly influence the resistance as well.

Also, you need to determine the width of the metal oxide layer. Insufficient thickness can lead to complications in the devices. A thin layer will allow more heat to pass through, causing the system to overheat and undergo major damage. 

Carbon Film Resistor Vs. Metal Film Resistor

It’s time to compare carbon film resistors and metal oxide film resistors. It will allow you to understand the strong and weak points of both these types. Also, it will help you to choose the most appropriate resistor for private projects and assignments at the same time. Experts believe that metal oxide resistors are always reliable as compared to carbon film resistors. Let’s see why: 

Voltage & Temperature Coefficient:

  • Metal oxide resistors are reliable with the voltage and temperature more than carbon film resistors.
  • These are dependable because of their ability to work efficiently with higher temperatures. Carbon film resistors cannot do it because their resistance is less and causes damage to the device as well. 

Noise Design:

  • You can trust them with the thermal noise, which is impressively low.
  • The less noise is due to the excellent resistance of the current that does not let it produce thermal noise. 
  • Due to less thermal noise, devices like radios, radars, and other telecommunication equipment include metal oxide resistors. 


  • The tolerance of metal oxide film resistors is extremely lower than that of carbon film resistors, which is 0.1%. 


  • Carbon film resistors are bigger in size, which makes their assembling and adjustment a little bit problematic. 
  • However, metal oxide film resistors are portable and compact as compared to carbon film resistors.

Availability of Carbon Film Resistor VS Metal Film

Carbon Film Resistor

The carbon film resistor has more power rating than metal oxide film resistors. It can go up to 5 watts. At the same time, metal oxide resistors have a power rating of just 3 watts. 

Factors that make an effect on the resistance:

  • Cross-sectional area and resistance (inverse relation)
  • Length and resistance (direct relation)
  • Carbon and resistance (inverse relation).

Metal Film

The appropriate metal films for a metal oxide resistor are available in the following: 

  • 2%
  • 1%
  • 0.5%
  • 0.25%
  • 0.1%

Factors that impact resistance:

  • Thickness and resistance (inverse relation)
  • Layer and resistance (inverse relation)

Construction of Carbon Film Resistor VS Metal Film

The design and construction of both resistors are different due to the assembly of different components in them. This construction sets them apart from each other, making them application-specific. So carefully read out the constructions of both resistors and choose the best fit for yourself later. 

Carbon film resistor Construction

  • A rounded substance is important to make the carbon film resistor.
  • It should be heavy-duty and highly durable.
  • The metallic capping and wiring take place at both ends of this cylinder-shaped material.
  • The resistive materials are basically a combination of graphite and carbon powder that goes with ceramic made of clay.
  • The carbon can conduct the current, and for this reason, it makes a great component of a carbon film resistor.
  • You need to heat the ceramic with methane which will use extremely high temperatures to start the reaction.
  • The graphite has carbon in the form of crystals which has the ability to strongly adhere to the ceramic during the reaction.
  • The plastic shield is important to conceal the resistive materials to not let them interact with heat that can eventually melt them down.
  • Copper wiring proves to serve well in the long run, so make sure you are using copper wiring at the ends of the cylindrical material. 

Metal film resistor construction

  • You need metal oxide for making a metal oxide film resistor.
  • Normally antimony oxide is a recommendable material for this purpose due to its excellent current conducting ability.
  • However, in case of a shortage of antimony, you can use Nickel chromium as well. 
  • Also, when you are constructing a metal oxide resistor, you need to observe the width of the metal oxide film as it influences the resistance. 
  • Keep the width, and it will reduce the resistance making the rod’s ends more dependable. 
  • You can later shape the resistor as per your requirements with the help of leads that will make it much more feasible for you. 


It is hard to choose between carbon film resistors and metal oxide film resistors. We totally understand this. Therefore, we hope this guide was of some use to you to evaluate the features and drawbacks of these resistors to make your future projects shine! Till then, we will catch you in the next post with something amazing from the world of physics!




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