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X-ray Inspection in PCB Assembly

Wednesday, June 15th, 2022

X-Ray Inspection’s Definition

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, X-ray inspection is one of the most important steps for quality-oriented PCB manufacturers.

X-Ray Inspection’s Working Principle

Generally, there are three elements in the X-ray devices.

X-ray tube—to generate the X-ray photons.
Operation platform—to move along with the sample so that the sample can be inspected from different angles and magnification.
Detector—it 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.

Solder bridges—it 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 voids—when 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 fills—pin-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 in the device’s 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 platform’s 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 a video about 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.

Types of Vias

Friday, May 20th, 2022

What is via?

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.

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.

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.

Why is the MCPCB Widely Used in the LED Products?

Saturday, April 30th, 2022

MCPCB refers to metal core printed circuit board. It has a good performance in heat dissipation, so it is often used in LED products.

The advantages of MCPCB

Prevent overheating:

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 material’s 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 product’s 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.

Why is the MCPCB widely used in the 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.

3M Epoxy Adhesive DP190-Gray & 3M Epoxy Adhesive DP190-Translucent

Friday, April 22nd, 2022

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-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.

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.

Thermal Conductivity—Aluminum PCB vs Ceramic PCB Series 2

Tuesday, April 19th, 2022

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.

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.

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.

Electrostatic’ s Power-Trivia Series 2

Monday, April 18th, 2022

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.

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.

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.

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.

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.

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.

Electrostatic’ s Power─Trivia Series 1

Wednesday, March 23rd, 2022

The Introduction to Electrostatic

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 “static electricity”.

As is known, we cannot touch PCB directly with our hands because of the electrostatic. But most of people have thought lowly of electrostatic’ 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%.

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 electrostatic’ 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.

What Should be Prepared Before Starting the SMT Process?

Tuesday, February 15th, 2022

SMT, whose full name is Surface Mounted Technology, is the most popular technology in electronic assembly industry. It refers to process on PCB (Printed Circuit Board), putting various electronic components on PCB, such as resistors, capacitors, inductors, and so forth. Also, there are some dos and don’ts in the whole process of PCBA.

As noted previously, there are all sorts of electronic components that will be used in the assembly process of Printed Circuit Board. Therefore, it is extremely important to take some measures to keep a check on static. Here are three steps before entering the SMT workshop.

First, put on anti-static clothes and hats. It is to prevent static existing in clothes and hair from influencing the board, for static has a potential and tremendous destructive power.

Second, 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.

Third, across the air shower door. In this way, dust that is invisible on our body can be blown off in about 5 seconds.

Only finishing the three steps above can we enter the PCB assembly workshop. And after entering the workshop, there are also something needed to be prepared.

Solder paste. The storage temperature of solder paste is 2-10 degrees Celcius, hence it has a period of regaining temperature, which conducts in the rewarming machine for 4 hours. Then the solder paste should be rabbled in a blender for 5 mins in order to help three ingredients in it to be fully integrated, which can help to achieve a better printing and back-flow soldering effect.

Oven. This machine is used to get rid of the moisture from materials or boards, ensuring that PCB will not be defective due to moisture during the subsequent assembly process. Moreover, different boards have different requirements. But generally, the baking parameter is 105 degrees Celcius, lasting 1.5 hours.

Dryer. It is used to maintain a set temperature and humility of materials and boards that needs to be processed that day, which is also to avoid that moisture does harm to materials and boards after removing the moisture by oven.

Tension test of stencils. Before manufacturing, the stencils’ uniformity should be tested by tensiometer, which mainly tests the four corners and the center part of the stencil, guaranteeing the solder paste printing quality. And the parameter should be between 30 and 45.

To sum up, although there are lots of preparations should be done before starting the formal assembly process, each of them is significant, for they will probably influence the quality of boards directly. Besides, only a good preparation can make a certain that the follow-up process can keep going. Thus, it is a must to prepare well in advance.

And Best Technology is an experienced electronic company. It not only can provide PCB A service, but can provide other services, such as FPC, FR4 PCB, Rigid-flex PCB and so on. And if you have any questions about SMT, or any other questions about assembly, you are welcome to contact us.

Advantages of LED PCB Compared with Common Standard PCB

Wednesday, December 22nd, 2021

With the development of electronic products, the requirements of circuit boards applied in electronic products are becoming higher and higher. The volume of printed circuit boards is also shrinking exponentially, the assembly density is increasing, and the internal wiring of the line layer is becoming more and more intensive. Compared with PCB, LED PCB with metal core can achieve better heat dissipation effect.

LED PCB material:

First of all, LED PCB space utilization is higher, it takes up relatively small space, but can withstand relatively high-power output.

It is well known that when the power of the circuit board is high, high heat will be generated. If the heat cannot be dispersed in time, it may lead to the shortening of the working life of LED products, and the more serious consequence is the safety problem of the circuit board due to overheating.

Therefore, in order to make the LED lighting system longer life, it is generally used to print the circuit board with metal core, and the characteristics of the metal core is relatively large density, strong thermal conductivity, conducive to heat dissipation effect.

LED PCB board design:

The LED PCB is also unique in that its components are located on the surface, rather than through holes, because the metal core at the bottom dissipates heat more quickly.

Some LED printed circuit boards have through-holes, especially multilayer metal core printed circuit PCB. Because the number of layers of the circuit board increases, the circuit layout is more complex, heat is more difficult to emit, and the existence of the through hole is to achieve faster heat dissipation. The drilling holes on the LED board are mounting holes, which are usually larger than the standard PCB through holes.

LED PCB solder mask color:

In addition, LED printed circuit board solder resistance layer color is also its characteristics.

The color of solder resistance layer on the LED printed circuit board is usually white, while the PCB board has a series of colors such as black, green and red and so on. This is also determined by the characteristics of LED boards in practical applications. Since LEDPCB board is usually used as backlight board, photosensitive solar ink is usually coated on the surface of the circuit board. White Taiyo Solder mask can achieve high temperature resistance, not easy to change color, high reflectivity, so as to achieve the reflection effect of lighting and better lighting effect.

Via Tented, Via Filled & Via Plugged

Monday, December 20th, 2021

Via Tented, Via Filled (filled with solder mask) & Via Plugged (Via In Pad â€“ Conductive material or Non-Conductive material)

One of the most confused idea during our PCB design is the difference between Via Tenting, Via Filling and Via Plugging. Designers often get mixed up between them and fail to take full advantage of the process.

Today, let us discuss them, so that you can be confident in specifying your design requirements clearly when submitting PCB files to Best Technology before final manufacturing.

Via Tented

What is via?

A plated through hole (PTH) in a Printed Circuit Board that is used to provide electrical connection between a trace on one layer of the Printed Circuit Board to a trace on another layer. Since it is not used to mount component leads, it is generally a small hole and pad diameter.

A. Three methods and definitions of via processing

There are three methods for via processing: via hole opening & via hole cover oil & via hole plug oil

1. Through hole opening window: it is the tin on the solder ring of the via (the tin is exposed like a plug-in pad). The window is usually used to debug the measurement signal. The disadvantage is that it is easy to cause a short circuit.

2. Through hole cover oil: it is the welding ring of the through hole (via) covered with solder mask ink

3. Through hole plugging oil: refers to plugging the hole with ink.

Secondly, the inspection standards for a processing method

1. Through-hole opening window is like a plug-in pad, and the window is sprayed with tin. Inspection standard: tin can be tinned, and tin can be easily tinned.

2. The inspection standard of the via hole cover oil: it is not easy to tin in the patch.

3. Inspection criteria for via plug oil: First, it must be opaque, and it must be covered and blocked by ink.

Finally, we are talk for comparison and distinction between via hole cover oil and via hole plug oil:

1. Via plug oil This process is an important supplement to via plug oil, so generally high-quality boards will require via plug oil. And often many engineers who are just entering the industry are stupid and unclear. So how do you distinguish between the two?

2. The requirement of via hole cover oil is that the ring of the via hole must be covered with ink. The emphasis is to ensure the thickness and coverage of the ink on the edge of the hole. The key control is that the ring does not accept false copper exposure and orifice oil. Thin

3. Through hole plugging oil is the production of plug holes with ink inside the holes of the through holes. The emphasis is on the quality and density of the plug holes. After the holes are plugged, no light can be transmitted.

4. The method of plugging the via hole is to first fill the via hole with ink to block the via hole, so that the ink on the solder mask will not flow into the via hole, so as to achieve the situation that the via hole does not appear yellow. (If you have strict requirements and place an order for via hole cover oil, the cover oil is usually not full or yellowish, you can change it to via hole plug oil later). In addition, the smaller the vias are, the easier it is to plug them. The vias of the fortress oil are not easy to be too large (the circuit board proofing plugging oil is directly plugged with ink, and the printing tape is plugged. It is recommended that the vias that need to be plugged are designed to be <0.5mm. This is also free; no additional money is required).

If you have more question Via Tented, Via Filled& Via Plugged, warmly welcomed to contact Best Tech for more FR4 design service.

PCB & MCPCB – Best Technology

Archive for the ‘bestpcb’ Category

X-ray Inspection in PCB Assembly

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Types of Vias

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Why is the MCPCB Widely Used in the LED Products?

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3M Epoxy Adhesive DP190-Gray & 3M Epoxy Adhesive DP190-Translucent

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Thermal Conductivity—Aluminum PCB vs Ceramic PCB Series 2

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Electrostatic’ s Power-Trivia Series 2

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Electrostatic’ s Power─Trivia Series 1

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What Should be Prepared Before Starting the SMT Process?

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Advantages of LED PCB Compared with Common Standard PCB

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Via Tented, Via Filled & Via Plugged

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