X-ray inspection is a technology used to inspect the hidden features of the target objects or products. As for PCB inspection, X-ray is commonly used in the inspection of PCB assembly in order to test the quality and find the hidden defects, which is one of the most important steps for quality-oriented PCB manufacturers.
X-Ray Machine
X-Ray Inspectionâs Working Principle
Generally, there are three elements in the X-ray devices.
X-ray tubeâto generate the X-ray photons.
Operation platformâto move along with the sample so that the sample can be inspected from different angles and magnification.
Detectorâit can capture the X-ray through the samples and then transfer it into the image so that we can find out whether there are defects on the printed circuit board.
The Hidden Defects that can be Identified by X-Ray
Since PCB has the higher density with the solder joints hidden and holes buried or blind, X-ray enable us to inspect the quality of the PCB and identify various hidden defects. And there are three common hidden defects that can be inspected by X-ray.
PCB’s Image Under X-Ray
Solder bridgesâit is a common issue that will occur when the solder joints are so close that they create a connection which is not allowed. And usually, the solder bridges will be covered by some components on the PCB. But they can be easily found with the help of the X-ray device.
Solder voidsâwhen gas or flux is entrained during welding, solder voids will be produced, which will lower the thermal conductivity at the solder joint and may cause physical defects. And X-ray can help to identify the solder voids
Pin-hole fillsâpin-hole fills issue is a common problem occurring in the plug-in components on the printed circuit boards. The X-ray device can be used to identify these errors, and can even quantify the missing filling amount.
Our X-Ray Inspection Device
The maximum size of the board that can be put on the deviceâs operation platform is 510*430 mm, while the maximum inspection size of the device is 435*385 mm. So here is the manifestation of the operation platformâs function. When the size of PCB is over 435*385 mm, the operation platform will move along with the board so that the board can be inspected thoroughly.
And here is an video about the operation of our X-ray inspection device.
So, this is the end of this article. In case if you have any questions, you are welcome to contact us via email at sales@bestpcbs.com. We are fully equipped to handle your PCB manufacturing requirements.
With hexagonal wurtzite structure and no other homomorphic isomers, AlN, aluminum nitride, is a structurally stable covalent bond compound, whose crystal structure is AlN4 tetrahedron formed by the dismutation of aluminum atom and adjacent nitrogen atom. And its space group is P63mc, belonging to hexagonal system.
The Features of AlN Ceramic
High thermal conductivity, which is 5 to 10 times than that of aluminum oxide ceramic.
Coefficient of thermal expansion (4.3*10-6/â) matches the semiconductor silicon material (3.5-4.0*10-6/â).
Great mechanical properties.
Excellent electrical performance, with high insulation resistance and low dielectric loss.
Multi-layer wiring can be carried out to achieve high density and miniaturization of packaging.
Non-toxic, conducive to environmental protection.
Ceramic PCB
Factors Impacting on the Thermal Conductivity of AlN Ceramic
At 300K, the theoretical thermal conductivity of AlN single crystal material is as high as 319 W/(m·K). But in the actual production process, its thermal conductivity will still be affected, which is often lower than the theoretical value due to the influence of various factors such as the purity and internal defects (dislocations, pores, impurities, lattice distortion) of material, grain orientation and sintering process.
Effect of Microstructure on Thermal Conductivity
The heat conduction mechanism of single crystal AlN is phonon heat transfer, hence the thermal conductivity of AlN may be mainly influenced by the scattering control of grain boundary, interface, second phase, defect, electron and phonon itself. In accordance with the solid lattice vibration theory, the relation between phonon scattering and thermal conductivity âλâ is as follows: λ= L / 3CV.
In the formula, C is the heat capacity; V represents the average velocity of phonons; and L stands for the mean free path. And it can be seen from the equation that the thermal conductivity (λ) of AlN has direct ratio with the mean free path (L), for which the larger âLâ is, the higher the thermal conductivity is. From the perspective of microstructure, the scattering can be caused by the interaction between phonons and phonons, phonons and impurities, and phonons and grain boundary. It will affect the mean free path of phonons, and thus impact on the thermal conductivity.
It can be learnt from above that the microstructure of AlN has a great influence on its thermal conductivity. Therefore, it is necessary to make AlN crystals with fewer defects and impurities in order to obtain AlN ceramics with high thermal conductivity.
Effect of Oxygen Impurities Content on Thermal Conductivity
There are studies show that AlN has a strong affinity with oxygen so that it is easy to be oxidized, leading to the formation of aluminum oxide film on its surface. Owing to the dissolution of oxygen atoms in Al2O3, the nitrogen in AlN is replaced, resulting in aluminum void and oxygen defect. In this way, it will bring about the increase phonon scattering and decrease of mean free path hence the thermal conductivity will be reduced.
Oxygen Content in AlN (wt%)
Thermal Conductivity (W/m·K)
0.31
130
0.24
146
0.19
165
0.13
171
0.12
185
So, it can be concluded that the types of defects in AlN lattice are related to the concentration of oxygen atoms.
When the oxygen concentration is lower than 0.75%, oxygen atoms evenly distributed in the AlN lattice, replacing the position of nitrogen atoms. And then the aluminum void is accompanied by it.
When the oxygen concentration is not less than 0.75%, the position of Al in aluminum nitride lattice will have a change. Then the aluminum void will disappear, causing octahedral defects.
When the oxygen concentration is higher, the lattice will produce extension defects such as polytype, inversion domain and oxygen-containing stacking fault. Moreover, based on thermodynamics, it is found that the amount of oxygen in AlN lattice is under the influence of Gibbs free energy (ÎG°). The larger the ÎG° is, the less oxygen is in the lattice, hence there will be a higher thermal conductivity.
Therefore, the thermal conductivity of aluminum nitride is seriously affected by the existence of oxygen impurities, which is a key point resulting in the decrease of thermal conductivity.
Thermal Conductivity can be Enhanced by Suitable Sintering Aids
In order to improve the thermal conductivity of AlN, the required sintering aids need to be added to lower sintering temperature and remove oxygen in lattice.
As matters stand, the addition of multiple composite sintering additives is followed with more interests. And the experiment shows that relatively dense AlN samples with less oxygen impurities and the secondary phase can be obtained by adding the composite sintering aids, Y2O3-Li2O, Y2O3-CaC2, Y2O3-CaF2, Y2O3-Dy2O3, to aluminum nitride.
In a word, selecting appropriate composite sintering additives can help to get lower sintering temperature and effectively purify the grain boundary, so as to obtain AlN with high thermal conductivity.
In case if you have any other questions about ceramic PCB or MCPCB, you are welcome to contact us via email at sales@bestpcbs.com. We are fully equipped to handle your PCB or MCPCB manufacturing requirements.
Ceramic PCB is used in various fields because of its high-quality thermal and mechanical advantages. The boardâs unique features and high thermal conductivity have enabled it to be used in devices big and small. But meanwhile, it is not flawless. There are also some disadvantages.
Ceramic PCB
Pros of ceramic PCB
It is supposed that you are familiar with the features below that the ceramic PCB has.
Excellent thermal conductivity.
Good insulation.
High temperature resistance.
Great mechanical properties.
Compatible with CTE (Coefficient of Thermal Expansion) of components.
High-density assembly possible.
Non-toxic, conducive to environmental protection.
Cons of ceramic PCB
There are also a few disadvantages that can be found in ceramic PCB. Some of the disadvantages are stated below.
Handling—Since ceramic is fragile, it entails careful handling. As ceramic PCB is made for tight spaces, it is very small and this makes it even harder to handle.
Availability—It is not as widely available.
Everything has two sides. And ceramic PCB has no exception. But if considering all the advantages and disadvantages, ceramic PCB still takes the win amongst all other boards.
So, this is the end of the article about the advantages and disadvantages of the ceramic PCB. In case if you have any other questions about ceramic PCB or MCPCB, you are welcome to contact us via email at sales@bestpcbs.com. We are fully equipped to handle your PCB or MCPCB manufacturing requirements.
A via plays an important role in multi-layer PCBs. It is used to make an electrical connection between the layers of a multi-layer PCB. Generally speaking, every hole in the printed circuit boards can be called as via.
A via is constructed by placing copper pads on each layer of the PCB and drilling a hole through them. And the hole is plated with copper that forms electrical connection through the insulation that separates the copper layers.
PCB Vias
Types of Vias
There are three main types of vias used in PCB: through-hole via, blind via and buried via.
Through-Hole Via
Through-hole via goes right through the printed circuit board from top to bottom and can be used to connect all the layers of a PCB. It is the most common via and is easiest to construct.
Blind Via
Blind via connects the outermost layer of a PCB to the next layer. Namely, it cannot be seen on the other side of the board and is therefore called blind via.
Buried Via
Buried via is used to connect internal layers of a PCB. And it cannot be seen on the surface of the board.
Via Types
In addition, it is always better to use multiple smaller vias rather than one large via since smaller vias can reduce the inductance and also provide an additional path to the current flow in case any of the vias fail.
So, this is the end of this article. In case if you have any questions, you are welcome to contact us via email at sales@bestpcbs.com. We are fully equipped to handle your PCB manufacturing requirements.
The metal cores of the thermal PCB can be aluminum, copper and steel alloys. Apart from being cheaper than copper, aluminum is known for its good heat transferring and dissipation abilities, which is the most common used. However, copper is considered to be a better performer. So, why does the aluminum become the first choice for the material of the MCPCB?
Aluminum base—The aluminum PCB offers good heat dissipation and heat transferring ability. Since they are also light in weight, the aluminum core PCBs are widely used in LED products.
Aluminum Core PCB
Copper base—The copper core board features a better performance than aluminum. But customers will usually choose the aluminum instead of copper, for it is relatively expensive. Also, compared with the aluminum, the copper is heavier and involves a tough machining process.
Copper Core PCB
Various base metals and their properties
Metal Base Material
Thermal Conductivity (W/m-K)
Coefficient of Thermal Expansion (”m/m-°C)
Aluminum
88-251
25
Copper
386
17
Based on the table, it can be known that although the thermal conductivity of the copper is better than that of the aluminum, its ability of thermal expansion does not perform better than the aluminum.
Therefore, there are some reasons why the aluminum is the first choice for the material of the MCPCB, including the lower cost compared to copper, light weight, excellent durability and its heat transferring capabilities.
And these are also the reasons that the MCPCB is widely used in the LED products as we mentioned in the last article.
So, this is the end of this article. In case if you have any questions, you are welcome to contact us via email at sales@bestpcbs.com. We are fully equipped to handle your PCB or MCPCB manufacturing requirements.
LEDs tend to get overheated very quickly. If a metal core printed circuit board is used, it solves overheating by transferring the energy from one side to another.
Improve the materialâs reliability:
The MCPCB plays a key role in the elements that heats up overly at times. It helps to divert the heat from one side to another where the heat has vanished, which improves the productâs life, making it much more durable.
Adapt to a high temperature:
Unlike the FR4 technology, the metal core printed circuit board can adapt to products with a high temperature, hence it proves to be very useful for LED products.
Since it is well-known that the LED products will emit a lot of heat. Based on the advantages, the metal core PCB can transfer heat quickly and prevent overheating. And Aluminum PCB is mostly used in metal core PCBs, for they can operate longer than other metals and longer shelf life.
Moreover, metal core PCB has a high conductive ability, hence there remains ample space for maximum LEDs, which allows producing sufficient light and achieving high performance.
Therefore, based on the advantages of the MCPCB, it is the prior option of the material for the LED products.
So, this is the end of the article. In case if you have any questions, you are welcome to contact us via email at  sales@bestpcbs.com. We are fully equipped to handle your PCB or MCPCB manufacturing requirements.
Both 3M Epoxy Adhesive DP190-Gray and 3M Epoxy Adhesive DP190-Translucent are a two-part epoxy adhesive that delivers exceptional performance with high shear and peel strength.
They can bond to a wide range of materials, such as metals, ceramics, wood, fiberboard, glass, rubber and many plastics. So, PCB is no exception. But what are the similarities and differences between them?
Similarities
Provide tough, strong bonds through high shear and peel strength.
Capable of bonding to a wide variety of different materials.
Deliver extended work-life, providing additional time for adjustment.
Exhibit good environmental aging properties, delivering long-term durability.
Differences
3M Epoxy Adhesive DP190-Gray has a moderately high modulus. With a 90-minute work-life, it reaches handling strength in approximately 10 hours and full cure in 7 days at room temperature.
Additionally, this epoxy adhesive has medium viscosity and self-leveling with a 1:1 mix ratio by volume. But its flexibility and elongation are moderate.
(3M Epoxy Adhesive DP190-Gray)
3M Epoxy Adhesive DP190-Translucent has a moderately low modulus. With an 80-minute work-life, it reaches handling strength in approximately 10 hours and full cure in 14 days at room temperature.
It has low viscosity and self-leveling with a 1:1 mix ratio by volume. Additionally, it features high flexibility and elongation.
3M Epoxy Adhesive DP190âTranslucent
This is all about the similarities and differences between the 3M Epoxy Adhesive DP190-Gray and 3M Epoxy Adhesive DP190-Translucent. It is supposed that you have known about them.
But if you still have any questions about them or PCB, please feel free to contact us. Because at Best Technology, we are fully equipped to handle your PCB manufacturing requirements.
Last time we have talked about the structure difference between the aluminum PCB and ceramic PCB. So, based on the different structures, whose thermal conductivity is better?
We have known that a single layer aluminum PCB is made up of copper layer, dielectric layer and aluminum layer. Meanwhile, the dielectric layer is the decisive factor affecting the thermal conductivity.
Generally, its thermal conductivity ranges from 0.8 to 3.0 W/m-K, but can up to 8.0 W/m-K. So, in terms of heat dissipation, the aluminum substrate does much better than FR-4 substrate. And it is a good choice for LED lighting products with high power.
Aluminum PCB
However, the heat-conducting property of ceramic PCB is superior to that of the aluminum PCB.
Since ceramic itself is an insulating material with a great heat-conducting property, it does not need a dielectric layer. Therefore, the heat can be dissipated directly through the ceramic.
Because of its excellent performance in heat dissipation, it is particularly suitable for the lighting product with ultra high power and those products which have a high demand of heat dissipation.
Ceramic PCB
To summarize, clearly, we can know from the table below that ceramic PCB does better than aluminum PCB in terms of thermal conductivity and heat dissipation. And this is mainly because of the dielectric layer, which is related to the functions of bonding, insulation and heat conduction.
The better the heat conduction performance of the insulating layer, the more conducive it is to the diffusion of heat generated during the operation to the device, hence it will be more conducive to lower the operating temperature of the device. That is to say, aluminum PCB will be subject to the dielectric layer, while ceramic PCB will not be restricted.
And, this is the end of the comparison of the thermal conductivity between aluminum PCB and ceramic PCB. If you still have any questions about them, please feel free to contact us.
Last time we have known that electrostatic discharge (ESD) account for the highest proportion of causes leading to the failure of high electrostatic sensitive devices and the generation of it. Therefore, today we are going to talk about what kind of damage the static will cause to the Printed Circuit Board and how to avoid it.
The Influence of Electrostatic
Under different circumstances, the electrostatic voltage carried by the human body ranges from hundreds of volts to thousands of volts. And when people touch the electronic components, there will be ESD, resulting in the damage to devices and the reduction of reliability. To make matters worse, ESD will break down the device and directly scrap the product.
PCBA
Besides, the ESD will lead to a large pulse current, which will generate a lot of heat in the chip and printed circuit board, making them burn out. Moreover, the integrated circuits (IC) are built with denser lithography lines than before so that their ability to withstand electrostatic discharge becomes weaker. Therefore, it is necessary to prevent it.
Elimination of Electrostatic
Since the static will has a great impact on the PCB and electronic components, it is extremely significant to take precautions against the electrostatic by taking some measures. And here are some measures carried for eliminating the electrostatic in our workshop.
Putting on anti-static clothes and hats. It is to prevent static existing in clothes and hair from influencing the board.
Anti-static Clothes and Hats
Wearing anti-static wrist straps. The principle is to discharge the static from the human body to the ground through the wrist strap and grounding wire.
Anti-Static Wrist Strap
Using static elimination instrument. What we have to do is to put just one hand on static elimination instrument, and do not leave our hand from it until the red light turns to green, which aims to eliminate the static existing in our body.
Static Elimination Instrument
Keeping a certain humidity in the workshop. Higher humidity is not prone to ESD. The higher the humidity is, the easier it is to conduct electricity. As a result, electrostatic cannot be stored in our body.
Using anti-static packaging. When packaging, we have different packaging ways, such as anti-static bags, anti-static bubble film and so forth. And what to be used in packaging is up to our clients.
Anti-static Bags
To sum up, electrostatic will cause damage to the Printed Circuit Board and electronic components so that it is necessary to take some measures to prevent it.
And this is the end of this trivia. If you would like to know more about PCB, you are welcome to contact us.
Static, the excess charge on an object, is a phenomenon caused by the unbalanced distribution of charge in the material system. When an object is charged, the charge will remain on the object unless it is removed by other objects, so it is called âstatic electricityâ.
As is known, we cannot touch PCB directly with our hands because of the electrostatic. But most of people have thought lowly of electrostaticâ s power, deeming that it is not strong enough to be harmful to some devices, especially electronic components.
On the contrary, electrostatic can be in some way devastating. According to the statistics, electrostatic discharge (ESD) account for the highest proportion in the ranking of causes leading to the failure of high electrostatic sensitive devices, which is 59%.
Pie Chart
The Generation of Electrostatic
There are various ways resulting in the generation of electrostatic. But, triboelectrification, namely indicating that electrostatic is generated by friction, is the most common one.
Where there is friction, there will be electrostatic. When walking, the shoes will rub with the floor, leading to the triboelectrification. Also, the frictions between our hair and clothes are so easier to generate the static that every movement in the PCB workshop will unintentionally cause the generation of static.
Then the static generated will have a great impact on the PCB and electronic components. But, how great the electrostaticâ s power is, or in other words, what kind of damage can it cause to the printed circuit boards or electronic components? And what can we do to eliminate the electrostatic?
We will talk about it next time, hence if you would like to know more, you are welcome to contact us, or you can continuously follow our blog site, on which we will keep sharing more information about PCB.
