Semiconductor PCB

If you’re looking for semi-conductor PCB, then you should read this guide.

It explores everything about semi-conductor printed circuit board – from the definition, benefits, design, fabrication to prototyping process.

Moreover, it also explores applications and various types of semi-conductor PCBs.

So, if you wish to learn more about semi-conductor printed circuit boards, read this guide to the end.

• What is Semi-conductor PCB?
• Benefits of Semi-conductor PCB
• Semi-conductor PCB Designs & Fabrication
• Semi-conductor PCB Prototyping
• Semi-conductor Components Sourcing for PCB Assembly
• Mounting Technologies for Semi-conductor PCB
• Types of Semi-conductor Printed Circuit Boards
• Application and Use of Semi-Conductor PCBs

What is Semi-conductor PCB?

In defining a semiconductor PCB, we have first to understand what a semiconductor is.

A semiconductor is a substance which exhibits the characteristics of both a conductor and an insulator. Under certain conditions, it can conduct electricity.

Semi-conductor classification

This quality makes it the most preferred medium when there is need to use electrical power in a controlled manner.

A semiconductor PCBs, therefore, can be defined as the base component on which a semiconductor device is connected.

Semi conductor PCB

Some areas of semiconductor PCB application include computers, smart watches, mobile phones, and digital displays.

Benefits of Semi-conductor PCB

Some of the main benefits of semi-conductor PCBs include the following:

1. Ability to direct flow of electric signals. This ensures that they are well regulated resulting into proper working of electrical devices.
2. Semiconductor PCBs are small in size. This has led to smaller and faster semiconductors.
3. Semiconductor PCBs are also less noisy compared to vacuum tubes.
4. The small size of semiconductor PCBs enables compatibility, which is very necessary for efficiency in electrical devices that use them.
5. Semiconductor PCBs are also way cheaper compared to the vacuum tubes.
6. Devices made using semiconductor PCBs are also shockproof and have a longer lifespan.

Semi-conductor PCB Designs & Fabrication

Now, this is a critical stage when you want to make printed circuit boards. Any mistake at this point will affect the performance of your electrical and electronics system.

Semiconductor PCB Fabrication

This refers to the process through which a semiconductor PCB is created. The steps involved can be narrowed down to four major classifications.

Printed circuit boards for semi-conductors

Step 1: Deposition

This term is used to refer to all processes that involve the transfer of materials onto the wafer. Several technologies are applied to make this a reality.

Such include physical vapor disposition, among others. In recent times, atomic layer disposition has been the most preferred.

Step 2: Removal

In this stage is essential in removing substances from the wafer. This is achieved through etching which can either be wet or dry etching.

In some instances, chemical-mechanization planarization is applied.

Step 3: Patterning

The deposited material obtained from the previous step is shaped in a process called lithography. Coating of the wafer is done at this stage with a photoresist.

Stepper is then used to align the mask in such a manner that intended parts are left exposed.

Step 4: Modification of electrical properties

This entails doping that is conducted on transistor sources. The same is done to the drains. Either diffusion furnaces or ion implantation achieve this process.

Furnace annealing is then conducted after the doping.

This is necessary for the activation of implanted dopants. Modification is further done to reduce the dielectric constant. This is achieved by exposure to ultraviolet light.

In most instances, oxidation comes handy in this modification. This helps in creation of semiconductor-insulator junctions.

Semi-conductor PCB

·FEOL Processing

Front-end-of-line refers to the process through which transistors are formed directly from silicon. Epitaxy makes this possible as it is possible to create a silicon layer with no defects.

After the depositing of epitaxial silicon is done, the crystal lattice is stretched.

This has a far-reaching consequence of enabling electronic mobility.

Alternatively, silicon on insulator can also be used at this stage to create an insulating layer. This is done in between silicon wafer and silicon epitaxy layer.

·Gate Oxide and Implants

At this stage, dopants are diffused, making it possible to obtain the required electrical properties.

Back-end-of-line (BEOL) processing

·Metal Layers

After the creation of semiconductor devices, they have to be interconnected. This results in the required semiconductor circuits. This is made possible in the BEOL process.

Wires to be used for electrical interconnection are created in this stage. The insulating material used in this stage is mainly silicate glass.

·Interconnect

Depositing of blankets of films of aluminum is done at this stage. They are then patterned and etched. This leaves the isolated wires.

Also, the deposition is made on exposed wires using dielectric material. Etching of holes is then done.

·Wafer Test

This test is then conducted to ascertain whether the wafers have not been damaged during the processing steps. Failure of most dies is an indication that the whole wafer has failed.

This wafer is scrapped off to mitigate costs that would be incurred when it is processed further. Virtual metrology is the most used method in predicting this kind of failure.

·Device Test

After completion of front end test, electrical tests are performed to ascertain whether the device is functioning correctly.

·Die Preparation

After testing, the thickness of the wafer is reduced using the backlap process. Other methods that can be used include back finish and at times water thinning. Wafer dicing is then done.

This refers to the breaking of the wafer into individual dice.

Semi-conductor PCB Prototyping

After the production of prototype boards, the next step should be the assembly process. The following is a step-by-step summary of how to prototype a semiconductor PCB.

Semi-conductor PCB prototyping

Step 1.Sourcing

In this step, the materials and components used in the assembly of semiconductor PCB are sourced.  After sourcing for these materials, the assembly process starts.

Step 2.Solder paste stenciling

A paste of solder is applied onto the board. This paste is mixed with flux in order to make the paste melt.

This makes it possible for the solder paste to bond to the PCB surface. Since there are designated parts that the solder paste should be applied to, stenciling is done.

Step 3.Pick and Place

In order to place the surface mount components, you use a pick and place machine. This will be useful in the mounting of components to the PCB.

This device is able to place the semiconductor components atop the existing soldering paste. These components are placed in preprogrammed locations.

Step 4.Reflow Soldering

The PCB is then passed through a reflow oven using a conveyor belt. The reflow oven has a number of heaters. For the solder on the solder paste to melt, the PCB is heated at 480 0F.

The temperature is then reduced so as to make the melted solder solid. As a result, the SMD components are attached on the PCB. In the event that the PCB is double sided, stenciling comes in handy.

Separately and on both sides, reflow is conducted.

Step 5.Inspection and Quality Control

Inspection for errors is then conducted at this stage. This evaluation will help in detecting flaws that might have arisen from the previous processes.

Inspection procedures include manual examination, automatic optical inspections, and x-ray inspection.

Step 6.Insert through hole components

In instances that the board has provision for through-hole parts, then you are suppose to insert them at this point. Put the board on another conveyor belt to take it back through the oven.

This will cover the board’s bottom absolutely with molten solder. This is not recommended for double-sided boards. This leaves us with the option of manually soldering through-hole components.

Step 7.Functionality Test

Semi-conductor PCBs goes through this as the last stage. Boards are attached to the semiconductor components. In the testing process, design flaws are noted.

When problems are detected, then you will have to rework the prototype. When it passes this test successfully, real assembly commences.

Semi-conductor Components Sourcing for PCB Assembly

When you are assembling your semiconductor PCB, there are specific components you ought to source for.

Semi-conductor devices

Silicon is the most used material in the manufacture of semiconductor PCBs. This owes to the fact that it is cheap and requires very simple processing.

It also has one of the best temperature ranges. This can be sourced from companies that process silicon.

When obtaining silicon from these companies, ensure that they are made into boules. These are the most preferred for assembly of semi-conductor PCB.

Normally, these boules have large diameters which necessitate the production of 300mm wafers.

Another component that has been used in the past is Germanium. It is more thermal sensitive when compared to silicon. In some instances, it is alloyed with silicon.

In such instances, it is used in high-speed devices. These can also be sourced from companies that process Germanium.

Another possible component is Gallium arsenide. This is also commonly used in high-speed devices.

However, it is not possible to make large boules from this material. This has an implication on the diameter of the wafer.

The sizes of wafer produced here are much smaller compared to silicon wafers. In essence, this means that the production of Gallium arsenide is more expensive compared to silicon.

Apart from the primary materials used in the manufacture of semiconductor PCB, other materials are under investigations.

The first one in this category is Silicon carbide. This has been used extensively in the manufacture of semiconductor PCBs used in the LEDs.

It is being studied with the prospects of using it in high-temperature operations. There are also prospects of using it on environments which exhibit ionizing radiation.

All the listed materials used in the manufacture of semiconductor PCBs can be sourced from companies that manufacture them.

Mounting Technologies for Semi-conductor PCB

Depending on the task at hand, there are many options of mounting components on semi-conductor PCBs.

Some of the most common options include:

Mounting components on PCB

•Through Hole Assembly on Semi-conductor PCB Assembly

When this technique is used, through-hole components get to be mounted on the printed circuit board.  The semiconductor components have leads which get them through the drilled holes.

After insertion of the components through the holes, the leads are soldered on the opposite side of the board. The soldering process is either automated or manual.

Step 1.Preparation of the surface that is supposed to be soldered is prepared. This enables the surface to be easily attached to the solder.

Step 2.This step involves the placing of the components on the board. These semiconductor components are inserted into the holes to enable soldering.

Step 3.The moment you have inserted the leads, you are supposed to heat them and the pads. This will enable the solder to melt.

Step 4.The next step is the application of the solder to the joint.

Step 5.The meeting point of the solder and the joint are supposed to be touched. This is done with an iron until when the adequate solder is flown. You are then supposed to leave the solder board to cool.

Inspection to ascertain whether the board has been made properly is done. This process has the advantages of easy prototyping and high heat tolerance.

They have better heat handling capacities and leads to stronger physical connections.

•Surface Mount Technology on Semi-Conductor PCB Assembly

This involves mounting of semiconductor components on the printed circuit board. It is widely preferred today compared tom through-hole assembly.

Components here are not inserted through holes. Leads are located under the packages. This makes contact with the surface of the board.

This is a complicated process that can never be undertaken manually.

Surface mount technology

Its main advantages are that they are automated and as such, they are simpler and faster. It also enables the making of smaller but very powerful designs which are also lighter.

This is owed to the fact that both sides are available for mounting semiconductor components.

It is also preferred because of its higher load capacity compared to through-hole assembly.

Semiconductor components mounted by SMT are likely to have lower resistance and inductance. This technique also has the advantage of higher production capacity compared to the through hole technique.

•Mixed Technology Semi-conductor PCB Assembly

When handling applications requiring capabilities of both SMT and THT, then this is the technology to use.

PCB Assembly

With this technology, you will be able to bring on board both THT components and SMT components on the PCB. The procedure involved is discussed hereby.

Step 1.Component-side SMD components are placed on the PCB, and then reflow soldered

Step 2.Glue the “solder-side” SMDs in place on the opposite side of the PCB.

Step 3.Through hole devices are then inserted into the holes on the board

Step 4.Soldering-All the components are soldered in one wave

Step 5.It is time to solder the elements that need hand soldering. Here, a lot of care must be taken so as not to interfere with the already soldered components.

Step 6.Finally, the assembly is tested and packaged, ready for delivery to the client.

This technique is very essential in a number of ways in that there are many applications which apply it. They can be used in communication devices, smart-phones, server boards among others.

Mixed techniques also have an array of advantages that cannot be obtained from other techniques.

Significant semiconductor components which have high power handling capabilities and the small ones can be manufactured.

These are also known to be highly efficient. More space is also available on the board owing to the fact that both sides are used.

This gives room for more components.  In this manner, therefore, the resulting devices are better performers in both power handling and processing speeds. In a nutshell, therefore, semiconductor PCBs assembled using the mixed method have the excellent qualities of both SMT and THT.

Types of Semi-conductor Printed Circuit Boards

Some of the most common types of semi-conductor printed circuit boards include:

Semi-conductor PCB

1)Single Sided Semiconductor PCBs

These are semiconductor printed circuit boards which have their components mounted on its one side. This is mostly done using through-hole assembly. It makes them the most uncomplicated printed circuit boards.

These PCBs are used to make some of the purest forms of electronics. This owes to their simple assembly process.

2)Double-Sided Semiconductor PCBs

These are circuit boards with two layers on which the components can be mounted. Copper is applied on both sides of the substrate. They are the gateway to complex electric devices.

In semiconductor PCBs, surface mount technology or mixed method is used to mount components on it.

3)Multilayer Semiconductor PCBs

All multilayer semiconductor PCBs have at least three layers of conductive material. They come in different forms. There are those with four layers, six layers, eight layers, and much more.

They are essential in the making of more complex devices and applications.

Semiconductor devices are also mounted on these boards using either surface mount technology or mixed method when need be.

4)Rigid Semiconductor PCB

This is a type of semiconductor PCB that can never be twisted nor folded into any other shape. They are the most preferred in terms of compactness.

Depending on the number of layers that they exhibit, any of the three semiconductor mounting procedures can be used. Rigid semiconductor PCBs can be used in the manufacture of computer motherboards.

5)Flex circuit Semiconductor PCB

They are made using flexible plastic substrates such as a polyimide. This kind of flexibility distinguishes them from rigid PCBs.

Depending on the number of layers that they have, the most preferred mounting procedure is applied.

Owing to its flexibility, it is used as a connector in various applications. This makes them useful in most sensitive industries.

6)Rigid-flex Semiconductor PCB

These are circuit boards that use both rigid and flexible board technologies. In so doing the advantages of both rigid and flex semiconductor PCBs are inherent in them.

Since they are composed of more than one layer, we use either surface mount technology or mixed technology.  They take minimal space and have less weight, making them ideal for most industries.

Application and Use of Semi-Conductor PCBs

Semi-conductor PCB

1.Audio & Video Equipment

Semiconductor PCBs are essential in building audio and video equipment. For them to function appropriately, they need transistors and integrated circuits.

Examples of such include stereos and digital cameras.

2.Digital Display

Digital displays such as LEDs also use semiconductor PCBs. For these to function effectively, there is a need for diodes which are components of semiconductor PCB. Examples include LED Televisions and adverts.

3.Computer Systems

Computer chips found in the CPU and the memory are made up of semiconductor materials. This makes it possible to minimize the space used.

4.GPS

Due to their ability to minimize the space used and to enhance efficiency, semiconductor PCBs are used in the manufacture of GPS.

5.LED Systems

Light emitting diodes are semiconductor devices which emitting light when forward voltage is applied to it.

6.Mobile Phones

Semiconductor PCBs are used in mobile phones assembly to help in regulating the flow of currents. They are also used in smartphone LCD screens.

7.Printers

Printers in most cases have the ability to scan documents through LED. They equally need transistors to function appropriately. This can only be achieved when semiconductor PCBs are used.

8.Navigation Equipment

Navigation equipment are used to send signals both in the aerospace industry and in the water vessels.

This communication has to be prompt and efficient. As such, semiconductor equipment are used.

9.Radar and Radio Systems

Radar and radio systems also send signals. For effective communication, there is need to incorporate semiconductors in the PCBs used.

10.Smart Watches

These also rely on diodes for display. Their PCBs have to be intergraded with semiconductors for display purposes.

11.Consumer Electronics

For efficiency in the flow of electric currents and efficiency, consumer electronics are made using semiconductor PCBs. Such include TVs, Computers, and , among others.

12.Safety and Security Systems

Security systems such as CCTVs have to incorporate semiconductor PCBs in them. This is essential in capturing images and their subsequent display on an LED screen.

13.Automotive Systems

Automotive features such as radio have to use these semiconductor PCBs. This owes to their reliance on electric power that makes them functional.

14.Telecommunications Equipment

Telecommunication gadgets, including smartphones, rely on semiconductor PCBs to work appropriately. They, for example, need diodes to make their screens functional.

15.Military Equipment

Military equipment such as the walkie talkies requires features that will make the communication transmittable efficiently.

This should be done with disregard to location. Such products can only be archived with the use of semiconductor PCBs.

Conclusion

Semiconductor PCBs plays a very significant role in the manufacture of a number of appliances. They are cheap and have very long lifespan.

With the elaborate assembly and fabrication process, you are assured that the semiconductor PCB can serve your needs.

Prototyping is important before rolling out the final semiconductor PCB. It helps in ensuring that there are no flaws that might lead to malfunctioning of the PCB.

The components mounting process you use should be compatible with the number of layers on your semiconductor PCB.

For any questions about semi-conductor PCBs, you can talk to our technical team now!