Venture Electronics offers Ceramic PCBs for Your Needs

Ceramic PCBs have printed circuit boards that are made using electronic ceramic materials. You can make these into various shapes that meet your needs.

Ceramic PCB

Ceramic PCBs have some of the most outstanding characteristics.

They can resist high temperatures and have high electrical insulation performance, among other advantages.

Frankly, there are many reasons that will make you want to go for ceramic PCBs instead of the other options. They are mainly preferred because of:

Ceramic printed circuit board

1.Higher Operating Temperature

Ceramic printed circuit boards will be handy for your devices that operate under very high temperatures.

This quality makes them unique compared to other circuit boards that are likely to fail when exposed to high temperatures.

Even in temperatures measuring up to 350 ºC, your devices will still work efficiently and effectively.

2.Lower Expansion Coefficient

Ceramic circuit board also assures you of low coefficients of thermal expansion. As a result, they pose lower risks of distortion resulting from temperature fluctuations.

Usually, when you use covalent materials including diamond, silicon carbide and silicon nitride, stronger bonds are established.

This, therefore, assures you of low coefficients in the thermal expansion.

3.Good Thermal Properties

This refers to the ability of the ceramic circuit board to conduct heat.

Ceramic PCBs have high thermal stability. This informs excellent electrical properties for your circuit board.

4.They Also Present High Modulus

This makes ceramic circuit boards the most effective PCB for devices that work under fluctuating thermal conditions.

5. Superior High-frequency Performance

Ceramic printed circuit boards also deliver excellent high-frequency performance. This is essential in determining the impedance and bandwidth of the transmission path.

The dielectric material found in ceramic circuits enhances frequency performance because it limits impedance on the signal path.

6.Lowers Initial Cost of Investing in Ceramic PCB Assembly

With ceramic circuits you will lessen the tests and the number of insertions needed, unlike other circuit boards, due to the material used.

The assembly process is also shorter compared to the other circuits.

7.Ability to Integrate Ceramic PCB Assembly Guarantees Small Package Size

Ceramic PCB also can integrate many electronic circuits in a tiny flat piece. This enables you to make your ceramic PCB into a smaller package compared to other circuit boards.

This integration also makes ceramic PCBs faster in their performance.

8.Parallel Processing Layers in Ceramic PCB Ensures Cost effectiveness in Dense Package

With a ceramic printed circuit board, you are in a position conduct parallel processing of the layers. This makes it cost-effective, especially in dense packaging.

This is unlike other printed circuit boards whose layers cannot be processed in the same manner.

9.With 0% Water Absorption, Achieving Hermetic Packages is Easier

With the ceramic package, you also have the option of using hermetic package, hence keeping the ceramic circuit board airtight. This prevents the passage of oxygen and other gases.

It also has the ability to prevent the absorption of water in case the package is exposed to such conditions.

Even though it has all these positives, let us also see some of the challenges when using ceramic PCBs.

Ceramic circuit board

1.Fragility

One challenge that you will face with these boards is their fragility. This attribute also limits the size of the PCB that you can make.

2.Expensive

There are many processes involved in the manufacture of ceramic PCBs. Added with the materials used in the process, you will find it to be an expensive venture.

Types of ceramic PCB

·Single Sided Ceramic PCB

A single-sided ceramic circuit board is one which has the conductive components mounted on one side of the board.

On the other side, you will have the conductive wiring done.

This is the simplest ceramic printed circuit board that you can ever make.

They are the most basic; hence you can use them in some of the simplest devices you make.

·Double-Sided Ceramic PCB

These are ceramic printed circuit boards with two conductive layers. The conductive components can thus be mounted on both sides of this circuit board.

This makes it possible for the traces to cross over one another. In so doing, you will end up with a highly dense circuit without necessarily soldering them from one point to another.

They are more compared to single-sided ceramic boards. You can, thus, use them to make more complex devices.

·Multilayer Ceramic PCB

In double-sided PCBs, we only have two conductive layers. However, in multilayered ceramic PCBs, the conductive layers are more than two. These layers are buried at the center of the material.

This makes them one of the most effective ceramic PCB for complex products.

·High-Temperature Co-fired Ceramic (HTCC) PCB

High-temperature co-firing is one traditional method used in manufacturing. This is made possible by making a mixture of aluminum oxide and an adhesive.

Other materials added into this mixture include a plasticizer, lubricant, and solvent. This results in raw ceramics.

These ceramic PCBs are roll-formed and curtain coated. You can then proceed to implement circuit tracing on the refractory metals such as tungsten and molybdenum.

It goes through several complex processes, including heating, cutting and lamination, and baking.

When you manufacture ceramic PCBs using high-temperature co-firing, you can effectively manufacture small scale boards. This is also effective for derived boards and carrier circuits.

When making large-scale boards, this method is never effective. Avoid using high-temperature co-fired ceramics since they have inappropriate shrinking tolerance. They also have unsuitable warpage and usually, have relatively high resistance of the refractory metals.

·Low-Temperature Co-fired Ceramic (LTCC) PCB

Low-temperature co-fired ceramic PCBs are usually fabricated using a mixture of crystal glass and glass composite. Another component added to the mixture is non-glass with adhesive.

You can generate the sheet and circuit tracing, then implement using gold paste. Ensure that the gold paste has high conductivity qualities.

After the cutting and accurate forming, you can proceed to place it in an oxidizing gas oven. Ensure that the temperature in the oven is at 900°C to enable baking.

Ceramic circuit boards manufactured using this process result into production of valuable metal paste.

This helps in circuit tracing and circuit board baking. These are made as long as small improvements are done on the thick film baking.

In the same footing, you can improve the precision of the product and tolerance as far as shrinking is concerned.

·Thick Film Ceramic PCB

There are two alternative thick pastes that can be printed on a ceramic base.

These include thick film gold paste and its alternative, which is dielectric paste.

They are taken through baking at temperatures below 1000°C. Although this type of fabrication is most favorable for large-scale ceramics, it is mostly avoided because gold is costly.

When you implement this method, the resultant technology is thick film copper. This is the most appreciated and accepted ceramic PCBs.

To prevent oxidation, baking of such ceramic PCBs is done in nitrogen gas. This is the most crucial consideration for this production method.

Moreover, the generation in the nitrogen gas will generate for you dielectric paste. This will depend on the complexity of the multilayer interconnection structure.

Ceramic PCB Component Sourcing

The first step in ceramic printed circuit board component sourcing is developing a Bill of Materials (BOM). This will help you remember all the components you will need, plus their precise characteristics.

This way, you will avoid wastage of resources by ensuring you spend only on what is needed.

After drafting your BOM, proceed to identify the best manufactures of the required components.

You can get these manufacturers online by surfing through their websites. This will also allow you to weigh factors such as cost, expertise, experience, packaging and shipping capabilities.

Ceramic PCB Components

Based on these factors, you can proceed to select manufacturers of the components you need.  When fully convinced that you have identified the best supplier, now go ahead and place an order.

Ceramic Printed Circuit Board Substrates

Some of the most popular ceramic PCB components include the following:

Aluminum Oxide ( Al2O3)

Aluminum oxide is also known as alumina. This is the most popular material you can use for your ceramic PCB because of the following benefits:

• First, it guarantees you good electrical insulation.
• It will also ensure that your ceramic circuit board can moderate excess mechanical strength.
• Aluminum oxide also has outstanding compressive strength.
• This material will further ensure that your ceramic is hard enough and guarantees moderate thermal conductivity.
• Alumina also has unmatched corrosion and wear resistance.
• It has excellent gliding properties and low density.
• Such a ceramic can also perform in temperatures up to 1,500°C.
• This metal is also relatively cheap.

You can source Al2O3 from distributors.

Aluminum Nitride( AlN)

This is another ceramic material with qualities you will desire.

• It has a combination of very high thermal conductivity and desirable electrical insulation qualities.
• Also, it has excellently high thermal conductivity properties.
• AlN guarantees you high electrical insulation capacity.
• It also presents biaxial strength and low thermal expansion.

The disadvantage inherent in this metal is that it is expensive.

You can source AlN from authorized distributors.

BeO

Beryllium oxide, also known as beryllia, is an inorganic compound.

It is a notable electrical insulator and guarantees you very high thermal conductivity. This is outstanding among all other non-metals except for diamond.

This thermal conductivity also exceeds that of a majority of metals.

You can source for this metal from the distributors. However, you should note that this metal is environmentally unfriendly owing to its toxicity.

Ceramic PCB Features

·Quick Turn

With an 18:1 drill aspect ratio, ceramic PCBs have quick turn. This gives them leverage over other PCBs under the FR4 classification.

·Wide Variety

Ceramic PCBs provide you with almost all the demands of your device in terms of layers. At the minimum, the PCB can have a single layer.

This can be up to 32 layers depending on your specifications.

·Production Quantities

The maximum panel size should measure up to 24 x 40. This is equal to 609.6 x 1016 mm.  This gives you the ability to produce it in large quantities depending on the intended device.

·Blind Buried Vias & Micro-vias

Another feature of ceramic PCBs is blind buried vias. The micro vias are also blind and buried. This makes it different from FR4 PCBs whose vias and micro vias are exposed.

Types of vias in ceramic PCB

Thick Copper

Thick copper, which helps in controlling impedance.

 Alumina ceramic PCB

Step by Step Ceramic PCB Design

Ceramic PCBs are different from other regular FR4 PCBs. As such, there are some considerations in their design. Use the following step by step guideline when designing Ceramic Printed Circuit Boards.

PCB Design

Step 1: Source for conductor material. This is usually copper of thickness ranging between 0.1 mm -0.3mm.

Step 2: Ensure you observe recommended copper thickness against trace space and width. For 0.1mm of copper thickness, the trace space and width should be 0.3mm; while 0.2mm copper, will require 0.4mm space and width.

Step 3: Ensure that there is an adequate working area, which should measure about 126 x 176 mm.

There are two main substrates that are used in designing ceramic PCBs. These include Al2O3 and AlN.

The thickness of the substrate should be 0.25mm. This is rarely used because it is costly.

You can also design the thickness to 0.38mm, 0.50mm, 0.63mm (standard), 0.76mm, and 1.0mm for Al2O3. Still, for AlN, you can make the thickness 1.27mm.

Step 4: After achieving the substrate thickness, ensure that you leave a margin of 0.3mm between the trace and the board’s edge.

This should be done at each side of the copper thickness at 0.1mm interval. At 0.2mm copper thickness, the margin should be 0.4 mm. At 0.3mm copper thickness, ensure that the margin is 0.5mm.

Step 5: The next step is to conduct a surface finish. Do this using Nickel. You also have the option of Aug-plating for the surface finish.

Ceramic PCB Fabrication

1. Thin Film Circuit Process

First, you will need to generate the ultra-line circuit patterns, which are formed on the ceramic substrate. You have a number of ways through which you can achieve this:

• The first option is magnetron sputtering.
• You can also conduct pattern lithography.
• There is also the option of dry wet etching.
• You can also perform electroplating thickening.

In thin film processing using thin film circuit process, metalize the ceramic with magnetron sputtering.

2. Thick Film Circuit Process

There are a number of thick film circuit processes at your disposal. The first among these is high-temperature co-fired ceramic. The second process that you can explore is low-temperature co-fired ceramic. Direct bonded copper can also  be used.

These are the steps involved:

• Drilling: Holes that you will drill mechanically on the board will be used to create connecting pipes. These connecting pipes will be in between the metal layers.
• Plated through hole: After you have drilled holes between the copper layers, you should not turn on the in-between circuits. To conduct the layer, you must have a hole on the wall that will connect the line.
• Dry film pressing: Here, you will make a photosensitive layer.
• Inner layer image transfer: You can use the exposure to transfer the image of the film that you will use on the board surface.
• The outer layer exposure: When you are through with attaching photosensitive film, the board will be similar to the inner layers. This photo film will define the areas of your PCB that should be plated and those that shouldn’t be plated.
• Magnetron sputtering: This will move the material from the source material to the substrate to help realize the deposition of the film.
• Etching – Formation of external lines: This is an essential procedure for your ceramic board fabrication. It ensures that unwanted materials are removed using chemical reactions.

The process removes specific graphics. You do this to expose the copper to be etched.

• Anti-weld coating: The primary purpose for the ceramic circuit board is carrying electronic components and achieving the purpose of connection.

After completing your circuit board, you will have to define where both electronic and non-electronic components will be placed.

You should protect the no assembly area using polymer material.

Prototyping usually paves the way for the actual assembly of your ceramic PCB. Use the following process to come up with your ceramic PCB prototype.

If you intend to do a full turnkey ceramic PCB production, then you will need a prototype for design and fabrication as well. The steps in designing and fabricating the prototype are as I have already outlined in the preceding sections of this guide.

 Aluminum oxide PCB – Photo courtesy: Nano Technology Product Base

However, if yours is simply to assemble, then you will only need the following steps when prototyping.

Step 1: Solder Paste Stenciling

Proceed to apply a paste of solder onto the board. Ensure that the paste is mixed with flux. This will make the paste to melt.

You mix the paste with flux to make it melt. This is necessary for bonding onto the surface of the board.

Stenciling helps you in curving out the designated points at which the solder paste will be applied

Step 2: Pick and Place

Use a pick and place machine to position the surface mount components. This will make it easy to mount components onto the PCB.

The device will effectively help you to place the ceramic PCB components on the preprogrammed locations.

Step 3: Reflow Soldering

Using a conveyor belt, pass the PCB through a reflow oven. There are numerous heaters in the oven which ensure that all the solder paste melt.

Proceed to heat your ceramic PCB then reduce the temperatures to solidify the molten solder. This firmly attaches the SMD components on your ceramic PCB.

For double sided ceramic boards, do a separate reflow for each side.

Step 4: Inspection and Quality Control

Conduct an inspection to detect errors in the board. This will be handy in exposing flaws with the board that may have occurred in earlier stages.

You have a number of inspection methods to pick from, including manual examination, automatic optical inspection and x-ray inspection.

Step 5: Insert Through Hole Components

If your prototype has provision for through-hole components, proceed to insert them.

Next, use wave-soldering method to solder the components. Certain components may need manual soldering. If the prototype should have components on both sides, solder the second-side components manually to avoid damaging those already soldered.

Step 6: Functionality Test

This is the last proto-typing stage that your ceramic PCB will have to go through. Inspect and note all detected problems.

If the prototype is satisfactory, proceed with the actual assembly. Otherwise, you may need to make a new prototype.

a)Lighting

It is important to work in a well-lit place because fabricating ceramic PCBs is a complex process. With a working space which is visually enhanced, you will be able to fabricate your PCB with utmost efficiency.

b)Pins and Forks

Ensure that you work with the appropriate pins and forks in the proper sizes.

This is because these PCB incorporates numerous small components, which you need to assemble accurately. It will also help to ensure you don’t damage the components.

c)Safety Gear

You will also have to wear appropriate safety gear to ensure that you are well protected throughout the process.

To protect your eyes from the fumes emitted by the acids being used, wear goggles. This will also protect you from particles that may fly off during fabrication.

In the entire fabrication process, make sure that you wear hand gloves to protect you from the harmful acids and chemicals. These gloves also enable improved grip.

d)Check Connections

Ensure that the source of power is functioning effectively.

You should also ensure that there is compatibility with the voltage that the PCB requires.

Failure to consider this may lead to short-circuiting. There is also the likelihood of electric shocks.

e)Proper Installation of Components

The last precaution that you should take is to check all the connections and the installations of the components.

When the contacts are loose, then there is the likelihood of short-circuiting. You should, therefore, ensure that all the components are firmly held onto the board.

Once you are through with putting the layers together, it’s impossible to correct the errors in the inner layers. You can detect errors using optical inspection of the panels.

Let us now examine the entire process of making a ceramic PCB. The process takes the following steps.

 Different types of PCBs

Step 1: The Design

First, come up with the design for the ceramic PCB. You can achieve this using design software. Trace width calculator helps you in coming up with the details for the inner and the outer layers of the board.

Step 2: Printing the Design

Use a plotter printer to print the design of the PCB on the board. This will produce a film which gives the details of the layers.

Step 3: Creating the Substrate

Pass the substrate through an oven to semi-cure it. This will pre-bond copper to both sides of the layer. This will later be etched away to reveal the design of the printed films.

Step 4: Printing of inner layers

Mount a photo-sensitive film made from photoreactive chemicals. This will harden when exposed to ultraviolet light. In so doing, the blueprints will be aligned to the actual print of the board.

Step 5: Ultraviolet Light

After aligning the resist and the laminate, take the board through ultraviolet light. This hardens the photoresist.

Wash the board with an alkaline solution to clean the unwanted copper, leaving the hardened photoresist intact.

Step 6: Layer-up and Bond

The layers await their fusion at this stage. The outer layers are usually joined together with the substrate. This process takes two steps: layering up and bonding.

The outer layer materials consist of the substrates covered with thin aluminum foil on the top and bottom of the substrate. This substrate also contains copper tracing.

Now, this is the time to bond the layers together. You do this on a heavy steel table using metal clamps.

Next, fit the layers securely into pins that are attached to the table. Ensure that they fit appropriately to avoid shifting during alignment.

You can then proceed to place a prepreg layer over the alignment resin.

Fit the substrate layer over the prepreg before placing the copper sheet. Then more sheets of prepreg can sit on top of the copper layer.

PCB Material – Photo courtesy: Orbotec

Use aluminum foil and copper press plate and the stack will be completed. You are now ready to take it through pressing.

For pressing, you will use a press bonding computer, which heats the stack, before it is cooled down

Step 7: Drill

You can now proceed to bore holes into the stack board with utmost precision. Ensure that the holes are drilled to a hairs-width.

Use an x-ray locator to identify proper drill target spots.

Before you start drilling, ensure that you place the board on a buffer material under the drill target. This will help to ensure that the enacted bore is clean.

These computer-aided drills usually have air-driven spindles which turn at around 150, 000 rpm. This might mislead you that the drill happens in a flash.

During the drilling process, each hole needs its special moment with the drill.

Step 8: Plating and Copper Deposition

This is where you fuse the various layers together.

When you have thoroughly cleaned the panel, you can proceed to wash using a number of chemical baths.

When doing the baths, the chemical deposition process will deposit a thin layer of copper on the panel’s surface. This is usually about one micron thick.

The copper will go into drilled holes generated previously.

Before this step, the inner surfaces of the holes are exposed to the substrate. The copper baths will help you in covering the walls of the holes.

Step 9: Outer Layer Imaging

In this step, you will again apply photoresist to the panel.

Pass the prepped panel through the yellow room.  The yellow lights don’t carry UV levels that can affect photoresist.

To prevent misalignment with the panel, secure the black ink transparencies.

When the panel and stencil come into contact, a generator will blast them with high UV light. This will further harden the photoresist.

You can then pass the panel through a machine that will remove the unhardened resist, which is protected by black ink opacity. In this process, you will invade the inner layers.

You should then proceed to inspect the outer plates, removing all undesired photoresist.

Step 10: Plating

Return the board to the plating room. At this point, electroplate the panel with a thin layer of copper.

The sections of the panel that you have exposed from the outer layer’s photoresist stage will receive copper electroplating.

After the copper plating baths, the next step is to conduct tin plating on the panel. This makes it possible to remove all the copper remains left during the etching stage.

Step 11: Final Etching

The desired copper is protected in this stage as you remove unwanted copper that will be remaining below the resist layer.

You can use chemical solutions to clear the excess copper. Tin will protect the useful copper in this stage.

From here, the conducting areas and even the connections are now appropriately established.

Step 12: Solder Mask Application

Before you apply solder mask to both sides of the board, ensure that you clean the board. You should then cover it with epoxy solder mask ink, then expose it to UV light.

Then proceed to pass it through the solder mask ink. The portions covered will remain unhardened, ready for removal.

Pass the board through an oven. This will cure the solder mask.

Step 13: Surface Finish

To add solder-ability to your ceramic PCB, chemically plate it with either gold or silver. Most manufacturers prefer silver to gold owing to the cost.

Step 14: Silkscreen

You can then proceed to complete the board by giving it ink-jet writing on its surface. This will indicate all the important innovation of the PCB. Pass your ceramic PCB to the last coating and curing stage.

Step 15: Electrical Test

This procedure will help you to confirm the functionality of the PCB.

It will also test the board’s conformity to your original design.

Step 16: Profiling and V-Scoring

This is the last step. You will cut different boards from the panel that you have made.

You have two alternative methods to achieve this. You can use a router or a v-groove. Both ways will enable you to easily pop out the boards from the panel.

The surface finish is a coating between the components and the bare board. It enhances solder-ability and guarantees protection over the exposed copper circuitry.

To add solder-ability to your ceramic PCB, you can chemically plate it with either gold or silver. Most manufacturers prefer silver to gold owing to the cost.

Aluminum nitride ceramic PCB – Photo courtesy: Hitech circuits

Step1:CAD Check

The first step in your ceramic PCB assembly process is to check your layout using a Computer Aided Design system.

This enables you to check your ceramic circuit for unforeseen malfunctioning.  It will help you check on all the design specifications.

This application also helps you in detecting any missing (not provided for) components and redundant ones.

These might negatively affect the performance of your ceramic PCB in the long end.

Identification of these design flaws will shield you from financial losses by helping you minimize instances of scrapped boards.

Step 2:Incoming Quality Control (IQC)

Before you proceed to SMT assembly, ensure that all the incoming boards are verified.

There are some requirements that you should ascertain. First, verify the model number and the quantities according to the BOM list.

Check on the shape of the board whether it is broken or deformed. You can also check whether it has a broken pin or it has been exposed to oxidation.

Step 3:Solder Paste Printing

Before adding the components to the ceramic board, you will need to add solder paste to the areas that require soldering. In this, place a thin stainless-steel stencil over the PCB.

This will allow you to apply solder paste to only the required areas. These are the bases on which the components will rest in the complete PCB.

A mechanical fixture holds both the PCB and the solder stencil in place. In the required amounts, the applicator places the solder paste. The paste is spread across the stencil by the machine.

When the stencil is removed, the solder paste will remain only in the intended locations. This is an essential part in controlling ceramic PCB assembly process.

Step 4:Pick and Place

After you have applied solder paste to the ceramic circuit board, you can proceed to the pick and place machine. This will place surface components on the PCB.

SMDs are the most common non-connector components on your ceramic board. The device will pick and place these components on your board using vacuum grip.

It then movers the component to the pick and place station. At this station, the PCB is oriented, and the SMDs placed on the surface of the board.

The components are subsequently placed on the soldering paste in the locations that you had preprogrammed.

There are also components that you can put on the surface of the PCB by hand as opposed to the use of a machine. Such components can then be soldered on the ceramic board’s surface in the following step.

Step 5:Reflow Soldering

After you have placed the components on the ceramic board, ensure that you send them through the reflow machines.

This is important as it will assist in melting and solidifying the solder paste, thus grounding the components of the ceramic board.

When this process is through, the ceramic board moves to a conveyor belt. This will then move it into a reflow oven.

This oven is made up of many heaters which will steadily heat the board, hence melting the solder in the solder paste.

Step 6:Inspection and Quality Control

When you are through with soldering the surface mount components after the reflow process, assess the board for quality.

In some instances, the reflow process compromises connection quality or even leads to a lack of connection.

This movement can also result in electrical shorts. This is because misplaced components can at times connect portions of circuits which should otherwise not connect.

You should check for these errors using a number of inspection methods, including:

·Manual Checks

This is possible for smaller batches. You can consider hiring the services of a QC inspector to confirm that the reflow process was effective.

This option is not feasible when dealing with a large number of boards

·Automatic Optical Inspection (AOI)

This is most appropriate for inspecting larger batches of ceramic boards. It uses high-power cameras to check the PCB.

The cameras are strategically placed at various angles, from where they view the solder connections.

Different colors of light assess quality. This allows the inspection machine to detect lower-quality solder.

AOI does this very fast.

·Automated X-ray Inspection (AXI)

This is another method you can use in inspection of your ceramic board. It is, however, not commonly used.

This method detects flaws including opens, shorts and even inadequate solder. It also detects excess solder, omitted electrical parts and misaligned components.

During this inspection, AXI detects and fixes the detected defects.

All connections are also checked, including the ones underneath chip package. In ceramic boards, this is still useful as it will help you see through the lower layers. This will help you detect any underlying issue.

Step 7:  Through-Hole Component Insertion

Some ceramic PCBs also incorporate through-hole components, apart from the SMDs.

These components use the holes to make passing signals from one side of the board to the other.

There are different soldering methods that you can use with through hole PCB assembly:

·Manual Soldering

This is a straight forward process. Usually, one person inserts and solders one component into a pre-defined PTH.

When the first person is through, the board moves to the next station. The second person then inserts a different component.

This cycle continues until all the components are inserted.

This could prove to be a long process depending on the number of components in question. All boards go through this process.

Manual soldering works best with small orders, and where not many PTH components are involved.

·Wave Soldering

This is the automated version of PTH component soldering. The process is different from the manual method.

When you have put the PTH components in place, you will transfer the ceramic board on a conveyor belt.

It then runs through a specialized oven. In the oven, molten solder washes the board’s bottom.

All the pins are then soldered at the board’s bottom at once.

This method is not possible when dealing with double-sided PCBs.

Step 8:  Conformal Coating

Depending on what you are developing your ceramic PCB for, you may need a conformal coating.

This is similar to a thick paint but can either be opaque or transparent.

It helps you seal the components and the circuits of the ceramic PCB. It also helps in preventing dust, chemicals, and even moisture from attacking the ceramic PCB.

Step 9:  Final Inspection and Functional Test

After the steps above, you then proceed to inspect the ceramic PCB for functionality. This is what is known as a functional test.

The test analyzes the ceramic PCB, simulating the expected conditions under which it will operate.

Run power and simulated signals through the board, then monitor the ceramic board’s electrical properties.

Unaccepted fluctuations in terms of voltage, current and signal output show failure of the ceramic board to meet the expected standards.

You have the options of either reworking such a board or scrapping it all together depending on the severity.

Step 10:  Washing and Drying

The manufacturing process can be mucky. When you solder the components, soldering paste is likely to leave behind a considerable amount of flux. The surface of the board can also be contaminated by human handling the boards.

These residues can be removed using a stainless-steel high-pressure washing apparatus. This should have deionized water, which is the best when removing residue from the PCB. This water poses no threat to the device.

After the washing, you will need to perform a quick drying cycle.

Step 11:  Packing and Shipping

After the assembly, you can proceed to package your ceramic PCBs. Your ceramic board is ready for shipment.

Packing PCB

To make sure that your ceramic PCB is of quality, testing is mandatory.

The assembly processes that a ceramic printed circuit board goes through is complex. This brings the possibility of defects ranging from improper loading of components to failure in the SMT equipment.

As such, you need to carry out tests throughout the production process. This assists you in detecting defects early and addressing them appropriately.

There are quite a number of testing methods, which I have already mentioned in the previous sections.

Testing PCB

Visual Inspection of Solder Paste

As we already discussed, this is one of the best methods for detecting and correcting problems early enough.

Benefits of Visual Inspection of Solder Paste

• It helps you reduce the costs and the time involved in reworking the ceramic board.
• It also minimizes wastage.

This method of inspection starts with the application of solder.

You will have to check out the correct deposition of solder paste on the pads. This will help you ensure that the components reflowed appropriately.

• In essence, this kind of test will help you prevent passing boards with solder bridges.
• It will also help you detect open circuits and fragile joints that are susceptible to failure.

Pre and Post Reflow Inspection

These two tests are equally essential elements in the inspection of your ceramic PCB for quality control.

Pre-reflow inspection allows you to detect placement errors when you can still easily correct them. This helps you avoid repetitive mistakes early enough in the process.

Components of ceramic circuit boards and the boards themselves are very sensitive to heat. Detection of flaws in them at this stage will help you avoid damage and destruction.

Alternatively, you can conduct post-reflow inspection using AOI.   The first step in this involves performing an inspection on all the SMT feeders.

You need to ensure that there are no worn vacuum nozzles and the alignment of the vision system is right.

There are many notable differences between ceramic PCB and FR4 boards. And specifically, ceramic PCBs present certain advantages when compared to the FR4 boards.

These advantages come handy in some applications.

There are different substrates that are used in the manufacture of ceramic circuit boards. As we already saw, they include aluminum oxide, aluminum nitride, and beryllium oxide.

FR4 vs Ceramic PCB

You can also include silicon carbide and boron nitride in this list. These two are also effective ceramic materials.

The first quality that sets the difference between the FR4 and the ceramic materials is thermal conductivity.

FR4 has a very low thermal conductivity compared to ceramic materials. FR4 conductivity is 20 times lower compared to aluminum oxide.

On the other end, aluminum nitride and silicon carbide boast 100 times better thermal conductivity compared to FR4.

The other alternative, Beryllium oxide, has even higher thermal conductivity capabilities.

However, Boron has the best thermal conductivity.

In FR4 circuit boards, which have high thermal demands, the low thermal conductivity is compensated. This is made possible through the metal structures which transport heat.

A number of strategies are used to drive heat away from both the inner and surface layers.

For the layers on the inner side, thermal vias and thermal planes are created. For the surface layer, cooling elements such as fans and thermal landings are used.

When using ceramic boards, you will not have to acquire these elements unless you are dealing with extreme cases.

This is because heat can be transported easily to a thermal landing. Active cooling and the device packaging for ceramics also come in handy.

Thermally conductive materials are the best electrical conductors. This is evident in ceramic PCBs.

The conductivity of these ceramic boards can be attuned through doping. This is the same method that you will use to set the resistance of the intended ceramic resistors.

Multilayer Ceramic Boards

There are many advantages inherent in ceramic multilayer boards. The guaranteed high thermal conductivity helps avoid hot spots formation.

This is prevented in both the surface and the inner layers of the circuit. You can attribute this to the fact that heat is transported in a uniformed manner throughout the board.

In FR4, you will realize that there is reliance on metal structures. If not so, then there is dependence on active cooling.

Also, this is supposed to transport heat away from different locations on board layers. This translates into hot spots formation in FR4 printed circuit board.

In cases of thermal cycling, there is the likelihood that FR4 boards will be exposed to fracture. This is because they use vias as access to the inner layers.

Mismatches are the main reasons for susceptibility to fracture. This is because these mismatches are inherent in thermal expansion coefficient that exists between FR4 and copper.

As a result, stress is built along the via barrel and butt joints on the in-pad vias. Such points become weakened, leading to susceptibility to fracture.

The designers have to be keen enough to rule out this failure.

Higher thermal conductivity, which spreads across the whole ceramic board, will ensure that the expansion is consistent.

As a result, the vias are safe from the exertion of high stresses in any particular section of the board.

With their outstanding mechanical strength, ceramic PCBs can endure high mechanical loads and high vibrations and shocks.

Ceramic boards are less likely to deform compared to FR4 under the same force.

There are many qualities to look out for when finding a PCB manufacturer in China.

Ceramic PCB manufacturer

• Experience and professionalism-Longer periods in the industry inform expertise in manufacturing ceramic PCBs.
• The turnaround time must fit well within your work plan.
• Cost-The cost should also be relatively fair in comparison to the other manufacturers. You can ascertain this by checking out the profiles of other manufacturers.
• Prototyping-It will also be important to go for a manufacturer that makes both the prototype and the actual PCB itself. This will be less tedious compared to where you have to make the prototype elsewhere.
• Proper Packaging-The manufacturer must observe the prescribed packaging standards to ensure the safety of the boards. The PCBs are fragile, and packaging must take that into account.
• Shipment-The manufacturer must be able to assure of product safety during shipment. Shipment must also be within acceptable timelines.

Ceramic printed circuit boards are popular owing to their many strengths that we already mentioned. Just to remind you, we said that they have:

• High thermal conductivity capabilities
• Low CTE and can resist chemical erosion
• Low dielectric constant.

Because of these strengths, ceramic PCBs have many applications, including:

Memory modules -Photo courtesy: CPU World

·Memory Module

Ceramic PCBs have the capability of high-density assembly. As a result, it can contain up to 4 IC chips.

This makes it one of the most reliable PCB for manufacturing memory module.

Memory modules in telecommunication products can be used in extreme environments. They are also more resistant to vibrations and shock.

·Receiving/Transmission Module

Receiving and transmission modules for radars in the communication industry are also made from ceramic circuits.

This is because aluminum nitride has higher thermal conductivity and low CTE. This makes the module effective and reliable in receiving and transmission.

·Multi-layer Interconnect Board

Ceramic PCBs are also used in the manufacture of multilayer interconnect board. This is because ceramic circuit boards are in a position to hold more components on the same board area.

This guarantees the making of more sophisticated devices in smaller packages, unlike when you use FR4 boards.

Ceramic PCBs have many benefits over other circuit boards, especially as a result of the strengths of the base material used. This informs some differences in the manufacturing process.

Because of these benefits, they usually have stronger capabilities and better efficiency.

It is always essential to choose the right substrate and to contract the best suppliers and manufacturers. This is because the boards are unique and require skillful handling.

When accurately fabricated and assembled, these boards work awesomely.