The Engineering Projects

Introduction to Ceramic Printed Circuit Board

Hello friends and welcome to this article. Today we are going to have a look at the introduction to the ceramic printed circuit boards. we have previously introduced what a printed circuit board is and we noticed that it is a very important part that makes electronic circuits complete and well organized. Having that in mind, we had also discussed several materials that build up these PCBs and today our focus is on the ceramic types of PCBs.

Introduction to Ceramic Printed Circuit Board

• This printed circuit board is referred to as ceramic PCB because of the substrate used in the construction of this board is made up of ceramic and it finds applications in special areas.
• The process of making this board is that copper is pasted on the surface that is made up of alumina ceramic which is the substrate material at a very high amount of temperature.
• Its substrate material offers a very high value of conductivity features, very great insulation factors and provides easy soldering surfaces.
• The most preferred manufacturing process is the laser rapid metalization technique which is a very important process.
• The structure of ceramic borders is very simple when compared to other types of these boards and it offers high-level operations than what is offered by the other type of boards.
• The size of the conductive layer used in this type of board is between one micrometer and 1-millimeter thickness.

How to order Ceramic PCB

There are many online PCB companies, where we can place our PCB orders and the best of them all is JLCPCB. JLCPCB is a China-based PCB Fabrication house and offers the cheapest PCB rates. It's quite simple to place your PCB order on the JLCPCB official site. Here are the steps:

• First of all, create an account on the JLCPCB site.
• They have an online PCB calculator, where you can calculate the final price of your order by adding all your requirements.
• Next, you need to upload the Gerber file of your PCB design.
• Finally, made the payments through an online secure payment gateway, they have multiple options i.e. Visa, MasterCard, PayPal.
• That's it, once your order got ready, you will get it through DHL express delivery service.

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Structure of the ceramic PCB

In this discussion, we shall have a look at a single-layer ceramic PCB. It consists of; the ceramic substrate layer, the copper layer and the solder mask layer. Let us have a look at the image below which is a double-sided layer ceramic PCB constructed through the normal method of lamination.

Ceramic substrate

• Compared to the FR-4, ceramic has good thermal conductivity and thermal insulation features and there in these boards, ceramic plays two very important roles one is about thermal dissipation and the other is about providing insulation between the board’s circuit layers.
• When double or multilayer ceramic PCB is required, vias are necessary for providing connection between the layers. To achieve this, vias are drilled through the ceramic substrate by the use of laser technology.
• The drilled vias are then filled with the copper core through plating.

Copper layer

• This is in form of a thin copper foil that is bonded to the substrate by the method of magnetic sputtering.
• After bonding the copper foil on the ceramic substrate, the circuit is etched on the copper by the use of the photoresist coating of the yellow light way.

Dielectric layer

• Made up of various materials such as epoxy resins, phenolic, etc.
• It is used to bond the structures of two adjacent ceramic substrate layers.
• This substrate has poor thermal conductivity properties compared to the ceramic material hence it ends up affecting the overall thermal conductivity of this board.
• it is important to note that ceramic boards can only be used in applications that have lower heat dissipation.

Solder mask

• this has the importance of protecting the exposed copper wires from solder, metals and damages from the environmental conditions.
• The solder mask is applied on the top layer of every PCB after completion of lamination. It might be white, green, beige, red, etc in color.

Single-sided layer ceramic PCB is shown below;

We can notice that it has a copper layer, the substrate layer and the copper shield but the dielectric is missing. This is because the two ceramic layers are bonded by the PP.

Types of Ceramic PCB

Ceramic PCBs are classified according to ceramic substrate material used and also according to the manufacturing method that was used. Let us have a deeper look into these classifications below;

Classification according to the type of ceramic substrate used

Alumina PCBs

They are the most used types of ceramic PCBs and aluminum oxide is the most readily available substrate.

Aluminum nitride PCBs

They are also commonly used PCBs but they are a bit expensive when a comparison is done with the alumina PCBs.

They gave high thermal conductivity and smartly higher frequency performance again when compared to the Alumina ones.

Silicon nitride PCBs

More costly when compared with the aluminum nitride PCBs. They have higher mechanical strength and toughness hence finding greater use in the power modules such as IGBT and military modules.

Silicon carbide PCBs

This is diamond and has high thermal conductivity and electrical conductivity. They find applications in the areas of laser technology.

Boron oxide PCBs

Has dozen times boron activities than the alumina ceramics but this type of ceramic is very poisonous. They find use in high power and frequency applications

Classification according to manufacturing.

High temperature co-fired ceramic – HTCC

This is the earliest method known for PCB manufacturing. The method is suitable for high power and not for high speed or high-frequency PCB manufacturing.

Direct bonding copper method – DBC

This one requires lower temperature compared to the HTCC. They have no PTH vias and they are mainly preserved for power electronic module packaging.

Thick film ceramic PCBs

This has a requirement that the circuit line space should be at 60 micrometers. They find their use in applications that require lower power utilization.

Low temperature co-fired ceramics PCBs – LTCC

They are usually multilayer and normally three-dimensional. They are best suited for communication devices with high frequency.

Thin-film ceramic PCBs.

Has very high precision circuits but the copper layer has a limited thickness. These types of PCBs find their use in high precision devices and also in very small devices development.

Direct platting copper PCBs

They are developed from thin-film technology and can be in 3D and has very high circuit precision. They find their use in high-frequency and high-power circuits.

Characteristics of the ceramic PCBs.

Ceramic boards have very distinct characteristics that always give them an advantage over the other type of boards. below is the list of these special characteristics;

• They are excellent heat conductors.
• Offers excellent CTA component compliance.
• With ceramic PCBs expect a high level of mechanical compatibility.
• They are not easily corroded by chemicals.
• It is very simple to do a high-density outline in these types of PCB boards.

Benefits/advantages of the ceramic PCBs

The ceramic PCB boards are given high priority due to a number of material features and characteristics that they offer which proves to be beneficial in the process of PCB manufacturing. The character of heat dissipation gives this board an advantage over the traditional types of PCB boards. components of the board are placed on the boards directly without the involvement of the isolation layer and this makes the flow of heat throughout the board better compared to the other types of boards. The following are some of the benefits that make this board the most preferred;

High thermal expansion

They are the most popular in the field of electronics due to their features that are unique. One of these features is that it provides a very high thermal coefficient expansion. These boards will still offer very high thermal conductivity even when operated at high temperatures.

Adaptability

These types of boards use a metal core. The metal core is used when the board is undergoing the engineering process. The board can be changed to a rigid carrier which will offer a stiff mechanical strength. This stiffness is very crucial as it allows the board to be used in both fluids and solids.

Durability

The ceramic material offers a lasting-results to the PCBs being manufactured. The toughness of the material used in the making of the board will protect it against routine wear and tear. In addition, these boards offer high thermal resistance which will slow down the decomposition of these types of boards and therefore increase their durability.

Stability

They offer very high stability which is a result of a stable dielectric property that originates from the dielectric materials. Due to the toughness of the ceramic materials, it has a natural resistance to many chemicals.

Versatility

It has a very high melting point hence it can be used in many applications for both low and high temperatures. The best thing about these ceramic boards is that they will offer good thermal conductivity while distributing heat evenly throughout the board and different positions of the devices.

Ceramic boards disadvantage

• It is very hard to find ceramic PCB boards because they are hardly available.
• When compared to the standard boards, the ceramic boards are very expensive.
• These types of boards are highly fragile and therefore they require handling with great care.

Ceramic PCBs applications

Memory module applications

It was done in Japan when a company crested an SRAM memory module by the use of the multilayer ceramic PCB. The ceramic PCB is appreciated for both high-density PCB and low-density PCB. Another example is about the USA company that had developed the telecommunication, aerospace and missile products using this type of board.

Transmission module

This is being done by an American company that is determined is building a transmission module for radar communication using the ceramic PCB boards.

Digital PCBs

Japanese have used low-temperature PCBs in the manufacture of digital PCBs. This is used because it reduces the weight of the circuit greatly. It also reduces the volume of the circuit.

Interconnect boards;

The ceramic boards are mostly used in printed circuit boards because they support the miniaturization of the devices. It has a very high probability in the application of the boards in multilayer interconnects.

Solar panels

HTCCs and LTCCs are both applied in the process of making photovoltaic panels. In this device, we shall use multilayer ceramic PCBs to make them tough and durable.

Electrical power transmitter

There has been an increase in the use of wireless power transmission systems and this implies that most power transmission system has to use ceramic boards to achieve that ability.

Semiconductor coolers

With the introduction of very small pocket gadgets, many electronic circuits are getting miniatured. To achieve miniaturization, it starts with the use of semiconductors that have a highly reduced size. The normal boards cannot give the support needed in order to make sure that the miniaturization process is fully achieved. In order to make this possible, ceramic semiconductors have been introduced and this is accompanied by the use of ceramic PCBs.

How to choose the right ceramic PCB manufacturer

When you are choosing the person or the manufacturer who can produce your board, you have to consider the manufacturer who has the superior tooling that is required to make the process successful. The manufacturer should be able to control the oxidation process so that the board can have superior thermal conductivity and higher temperature resistance.

Ensure that the manufacturer uses the automated process to do the manufacturing and this will make sure that your board is in perfect condition and of very high quality and the process will be less time-consuming.

Introduction to the MATLAB Datatypes

Hello friends. In this lecture, we are going to have a look at the different kinds of MATLAB data types.

As we have already seen in previous lectures, MATLAB stands for MATrix LABoratory and allows us to store numbers in the form of matrices.

Elements of a matrix are entered row-wise, and consecutive row elements can be separated by a space or a comma, while the rows themselves are separated by semicolons. The entire matrix is supposed to be inside square brackets.

Note: round brackets are used for input of an argument to a function.

A = [1,2,3; 4,5,6; 7,8,9];

An individual element of a matrix can also be called using ‘indexing’ or ‘subscripting’. For example, A(1,2) refers to the element in the first row and second column.

A larger matrix can also be cropped into a smaller matrix, as we can see in the example below.

A scalar is just a special case of a matrix and its element size is 1x1. Square brackets are not needed to create a scalar variable. Also, a vector is a special case of a matrix with a single row or column. Square brackets without an element inside them create a null vector. We see examples of this in the code below:

• u = [1 2 3]; %Produces a row vector
• v = [1;2;3]; %Produces a column vector
• X = []; %Produces a null vector

Elements of a matrix can be all kinds of numeric datatypes, whether they are floating-point, integers, or imaginary numbers, as we will see in the next section. They can even be symbolic.

DataTypes of MATLAB

Every variable that is stored in the workspace of MATLAB has a datatype. It can be an in-built or default datatype or users can build their own datatypes depending on the purpose of the code.

You can always find a datatype in MATLAB by using the 'class’ function.

Numeric datatypes:

Double:

• This datatype takes 64 bits to store a number. This essentially represents a floating-point number, i.e., a decimal number with double precision, and can be positive or negative. You can use the function ‘double’ to declare the datatype when creating a variable, but double is the default datatype in MATLAB and whenever you call a command such as the one shown below, the number is stored as a double.

• These variables can store values varying from between -1.79769 x 10³⁰⁸ and -2.22507 x 10^-308 for the negative numbers and the range for positive numbers is between 2.22507 x 10^-308 and 1.79769 x 10³⁰⁸ In situations where such large values of numbers are not needed, single-precision floating-point variable can be used.

Single:

1. When storing smaller numbers, it is better to use the single-precision floating-point numbers which vary between-3.4x10^38 and 3.4x10^38. This stores a variable in only 32 bits and helps to speed up the code. We use the function single in order to create this kind of variable.

Integers:

• MATLAB supports four types of signed integers and four types of unsigned integer datatypes, given by, int8, int16, int32, and in64 for the signed integers, and uint8, uint16, uint32 and uint64 for the unsigned integers. The number refers to the number of bits required to stored these integers and the range of allowed numbers is decided accordingly.

Complex numbers:

• You can create a complex number by using the ‘complex’ function or using the default symbol ‘i’ for the imaginary part of the complex variable. We can also extract the real and imaginary parts of the complex number using the ‘real’ and ‘imag’ functions on the complex number.

Infinity and Nan:

• Any number larger than the range given above is represented in MATLAB by the value ‘Inf’. Such a number can result when we divide by zero, which leads to results too large to represent as floating-point values and they end up being outside of the ranges discussed above. We can check if a variable is an infinity or not by using the function ‘isinf’ on it. Some numbers that can’t be represented by a real number such as the result of calculating ‘0/0’ or ‘inf/inf’ are called NaN, i.e., “Not a Number”. We can check if a variable is NaN or not by using the function ‘isnan’ on it.

Logical:

• These are variables that only have values of 0 and 1, and are the result of a comparison operation. An example of a result of comparing two matrices that gives a logical matrix as an output is shown below:

Representation

We can represent the output of a double in a shorter format which is easy to read or in a longer format which will help with learning about the accuracy of those double variables, using the commands below:

• format short
• format long

Conversion of numeric datatypes:

We can convert between double or single-precision numbers, as well as from floating-point to integers or vice versa using the functions described above which we use while declaring the numeric data type.

Operations on numeric datatypes:

Following is a list of operations on the numeric datatypes.

• abs: to determine absolute and positive value of a signed or complex number.
• Fix: round-off a floating point number towards 0. For example, fix([-2.1, 2.9]) = [-2, 2]
• floor: round-off a floating point number towards –Inf. For example, floor([-2.1, 2.9]) = [-3, 2]
• ceil: round-off a floating-point number towards +Inf. For example, ceil([-2.1, 2.9]) = [-2, 3] round: round-off a floating-point number towards the nearest integer. For example, round([-2.1, 2.9]) = [-2, 3]
• Rem: Remainder after division of first argument by second argument. For example, rem(10,3)=1
• Sign: signum function returns the sign of a number.

Other datatypes:

Characters/strings:

• The character or string array is used to store text data in MATLAB.

Single quotes are used to declare a character array. For example,

A = ‘Hello World’ is a character vector.

However, double quotes are used to declare a string. String is different from a character because individual parts of a character array can be accessed using indexing but the same is not true for strings.

You can carry out the exercise shown below to understand this subtle difference.

The various operations that can be performed on character array include:

Cell matrix:

• Just like matrices, a cell array is an indexed data container with each element known as a cell and can contain any type of data, including other cells and arrays which can be numeric or non-numeric types. Cells can be declared with curly braces, { } to let MATLAB know the input is a cell array. Individual cells inside a cell array can be called using round parentheses whereas contents at a location can be accessed by curly braces again, as shown in the example below:

The function ‘cell2mat’ takes a cell as an argument and outputs a matrix. However, for this, all the elements of a cell array must be the same data type. This is what distinguishes Cell arrays from Matrices.

Tables:

• A table is a convenient data structure to write column-based or tabular datasets that can be stored in a text or spreadsheet file, or plotted easily as well. Tables let you access individual columns with variable names. Each variable can be a different datatype. The only restriction for different columns is for them to have the same number of rows. You can load the inbuilt tabular dataset inside MATLAB as shown below.

Structures:

• Structures are the most generic datatype in MATLAB which consist of indexed elements and each index can store a different datatype or in fact, a structure itself. Such structures are known as nested structures and the various branches of a nested structure can be accessed using the dot notation.

Non-numeric datatypes also include function handles, symbolic variables and anonymous functions but they are a topic worth a separate lecture for discussion and will come up in the upcoming lectures.

In further chapters, we will look at some of the applications of MATLAB in Linear algebra, look at different kinds of matrices inside MATLAB that are commonly used in a linear algebra class, and also work with input and output of data and functions using ‘m’ files as well as ‘mat’ files. We will also read about saving and loading operations, for input and output of data from MATLAB, and we will look further at making GUI in MATLAB, plotting linear, polar, 2D and 3D graphs with data sets.