Archive for the ‘PCB Technology’ Category

Why ENEPIG More Suitable for Ceramic PCB Wire Bonding?

Thursday, October 20th, 2022

There are many surface treatment choices that can be used on Ceramic PCB, but why ENEPIG is one of options we always recommend to our customers whom have wire bonding demands?

In the application of Ceramic PCB, COB or wire bonding was widely used for the packaging technology in thin, short, high speed of electronic products. The Chip On Board (COB) technology refers to a technology in which bare chips are directly attached to the PCB board and then connected electronically through metal wires, namely “Wire Bonding”. Due to gold wire has an excellent electrical conductivity, thermal conductivity, corrosion and oxidation resistance, gold wire is often used as a main bonding material in microelectronics packaging.

What is ENEPIG?

ENEPIG, is a type of surface treatment on Printed Circuit Boards and ceramic PCB, the full name of it is Electroless Nickel – Electroless Palladium – Immersion Gold, now it is widely used in wire bonding field.

How does it work and what’s the standard thickness of each layer?

  • Electroless Nickel: Nickel acts as a barrier layer, preventing copper from interacting with the other metals involved in this plating technology, particularly gold. The layer is deposited on the catalytic copper surface using an oxidation-reduction reaction. The result is a layer that is between 2.0 to 5.0 microns thick.
  • Electroless Palladium: Palladium is a relatively stable metal at room temperature, and it is difficult to be oxidized within 400℃. The chemically deposited palladium layer has a neat lattice arrangement, uniform grain size and compact structure. Adding palladium layer between nickel layer and gold layer can effectively prevent the diffusion of nickel layer to gold layer. The Palladium is a layer with a thickness between 0.03 to 0.10 microns, it also depends on the final applications.
  • Immersion Gold: The main function of the gold layer is to bond with the gold wire. If there is no palladium layer as a diffusion barrier between the nickel layer and the gold layer, the gold layer can also bond with the gold wire after reflow, as long as the gold layer reaches a certain thickness. For example, when the thickness of the electroplated nickel gold reaches 0.3um, it can bond with the gold wire. In addition, gold itself has a good bonding ability with gold wire, and in ENEPIG process, due to the palladium layer protects the gold layer from the pollution of nickel, only a thin gold layer (0.03um~0.05umm) is needed to have a good bonding property. This’s why there’s cost advantage of ENEPIG than that of thicker ENIG.
(ENEPIG product)

Why choose ENEPIG?

ENIPIG has a good wiring bonding ability, solder joint reliability, multiple reflow soldering and excellent storage time, can correspond to and meet the requirements of a variety of different assemblies.  Below is a comparison about performance of different surface treatments:

(Comparison-about-performance-of-different-surface-treatments)

Advantages  of ENEPIG

  • “Black Nickel” free — The palladium layer separates the Nickel layer from the gold layer, it can prevents the mutual migration of gold and nickel, so no black nickel will appear
  • Excellent gold wire bondability — the gold plating/coating is very thin, can be used for gold wire bonding as well aluminum wire bonding
  • Palladium acts as an additional barrier layer to further reduce copper diffusion to surface, thus ensuring good solderability
  • Cost-effective than ENIG
  • Lead-free nickel
  • Good compatibility between coating and solder paste
  • Very suitable for packaging components such as SSOP, TSOP, QFP, TQFP, PBGA

Best Technology is a 16+ years PCB manufacturer and we made many ENEPIG PCBs and ceramic PCBs for our customers, welcome to contact us if you have demands on ENEPIG PCB.

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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 Machine

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.

PCB’s Image Under 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.

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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-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 DP190–Translucent

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.

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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.

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.

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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%.

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 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.

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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.

Anti-static Clothes and Hats

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.

Static Elimination Instrument

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

Air Shower Door

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.
Solder Paste
  • 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.
Oven
  • 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.
Dryer
  • 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.
Stencils

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 PCBA 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.

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Via Tented, Via Filled & Via Plugged

Monday, December 20th, 2021

Via Tented, Via Filled (filled with solder mask) & Via Plugged (Via In Pad – 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.

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A Brief introduction for different layers on Multilayer PCB

Friday, October 29th, 2021

When it comes to multilayer PCB, we know the multilayer PCB are consisted by many different layers. Do you know what’s the purpose for these layers?

Here I would like to give you a brief introduction for the functions of each layer on a Multilayer PCB design.

Mechanical layer: There may be one or several mechanical layers in a PCB depending on the design. There should be at least one mechanical layer as it shows the physical dimensions of the board. Generally, it used GM1, GM2 to name the file on the Gerber.

Solder paste layer: This is a material applied onto the PCB layers where components are mounted, mostly through soldering. It helps with the bonding of the solder with the component pin and improves the solder flow. PCB Assembly supplier will make stencil according to the solder paste layer on the Gerber.

Generally, it used GPS, GBS to name the file on the Gerber.

Solder mask layer: This layer is a mask or a protective coating applied onto the board to prevent damage and contamination. It is typically green in color; however, you can also choose other colors such as blue, black, white depending upon your requirements. Generally, it used GBS, GTS to name the file on the Gerber.

Ground planes and power planes: These are layers for copper, the ground and the power planes are connected to an onboard voltage point. Generally, it used GND, PWR to name the file on the Gerber.

Split planes: This is a modified version of power and ground planes; they are split in a manner that they can be connected to multiple voltage points or potentials.

Keep out layer: This layer is crucial as it defines the working boundary and keeps it separate from the outer mechanical layer. Generally, it used GKO to name the file on the Gerber.

Silkscreen layer: This is typically the text displayed on the boards through which you can identify components with their names. It is typically white in color when solder mask color is green, black, blue and red. But you can also choose other colors such depending upon your requirements. Generally it used GTO, GBO to name the file on the Gerber.

Routing layer: These layers help to interconnect the components. They can also be present on the top and bottom layers of the board.

Drilling Layer: This is the layer to show the drilling information of the PCB. Usually, it names DRL on the Gerber.

Once we understand the purpose of each layer for PCB, then understanding the construction of PCB becomes easy, no matter how complicated the board structure.

With over 15 years of PCB manufacturing experience, BEST Technology can meet different requests from customers no matter it is prototype or high-volume PCB.

Send us your request, let us to make the high-quality printed circuit boards for you.

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About the “heat” problem in PCB & MCPCB

Monday, October 18th, 2021

For high-power products, the concept of “heat” is often mentioned, which is especially important in high-power products. It not only determines the service life of the product, but also relates to whether the product can work properly.

We will explain the “heat” problem in circuit board design from three aspects: the generation of heat, the impact of heat on the product and the “heat” in the system layout.

1. Heat generation:

Heat generation in a system takes several paths:

1) Power consumption of the component itself

2) Efficiency of power conversion devices

3) High frequency signal conversion heating

4) Power consumption of contact resistance and wire resistance during signal transmission

2. Impact of fever on products

The operating temperature of components is generally below 80 degree, and the operating temperature of commonly used capacitors and resistors is generally controlled below 50 degree. If the temperature of the system is not controlled, the following conditions may occur:

1) The temperature rise will cause the working parameters of components to change, resulting in the unstable working performance of the whole system.

2) Temperature rise will accelerate the aging of components, affecting the accuracy and life of components.

3) Temperature rise will cause circuit board deformation and poor connection of components.

General heat dissipation components arrangement

3. “Hot” considerations in system layout

1) Selection and layout of the chassis: choose materials with good thermal conductivity, such as aluminum alloy

2) Black heat absorbing material is coated inside the shell to enhance the function of radiation heat absorption

3) The shell is closely combined with the components with high calorific value to conduct heat dissipation

4) A large number of heating components should be placed at the edge of the plate to shorten the heat transfer path. Heat-resistant components should be kept away from light sources.

5) In the design process, the appropriate wire width and copper thickness should be selected, and the influence of wiring density on the current-carrying capacity should also be considered. Copper foil should be filled in the gap of the board surface as far as possible for heat conduction. The heat conduction hole can help effectively heat dissipation and reduce local temperature.

In the design of circuit board, how to effectively control the temperature of the system is a problem that must be considered.

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The function of solder mask layer on the PCB Board.

Monday, September 20th, 2021

At last time, we shared a blog talking about Why most of the PCB boards are green?. Believe you’ve known the reasons for why most of solder mask colors are green.

Today, let’s share something about the function of solder mask on the Printed Circuits Boards.

The solder mask layer is designed mainly to prevent the PCB copper foil from being directly exposed to the air and play a role in protecting the PCB surface, which is also to prevent the area that should not be soldered from being soldered.

PCB Solder mask

As we know that almost all the PCB need to do the assembly, which need to go through the reflow soldering while the assembly, and solder mask plays an important role during control of the reflow soldering process.

Here is a summary for what solder mask roles played on the board:

(1) Prevent physical disconnection of conductor circuits on the circuits board;

(2) In the welding process, solder mask can prevent short circuit caused by bridging;

(3) solder mask can reduce copper pollution to the soldering trough;

(4) Print solder mask on the PCB can prevent insulation deterioration and corrosion caused by external environmental factors such as dust and moisture;

(5) Solder mask are with high insulation; it is possible to increase the density of the circuit.

Red solder mask

In terms of solder mask material, it must be used through liquid wet process or dry film lamination.

Dry film solder mask materials are supplied in a thickness of 0.07-0.1mm (0.03-0.04″), which can be suitable for some surface mount products, but this material is not suitable for PCBs with tighter pitches.

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