Archive for the ‘PCB Technology’ Category

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℃, and the operating temperature of commonly used capacitors and resistors is generally controlled below 50℃.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 contact 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.

You may also like

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.

You may also like

Why most of PCB boards are green?

Tuesday, August 24th, 2021

You may have found such a situation, most of the PCB boards are with green colors, while other colors are relatively rare to see, do you know why?

As we know that the Printed Circuits Board consists of Solder Mask Layer, Silk screen layer, solder PAD, Copper traces, surface finishing and other parts, etc.

Among them, the solder mask refers to the part of the PCB that is covered by oil. Since most PCB boards use green oil, the part of the green oil that can be seen on the board surface is the solder mask, which play an important role during the reflow soldering process.  

green solder mask

Then why are most of the PCB boards green? The main reasons are as follows:

  1. Green is less irritating to the eyes. We all know that green is good for the eyes and can resists fatigue. So when the PCB board with green solder mask, relative production and maintenance personnel are not prone to eye fatigue when staring at the PCB board for a long time, and it is less harmful to the eyes.

2. Cost for Green oil is lower. Since green is the mainstream in the production process, the purchase of natural green oil will be larger, and the purchase cost of green solder mask will be lower than other colors. At the same time, using the same color oil in mass production can also reduce the replacement cost.

  • When the board works on the SMT soldering process,  it needs to go through the process from Tinning, post soldering and final AOI inspection. These processes all need to be optically positioned and calibrated. The green background color is better for the recognition of the instrument.
PCBA AOI testing

Okay, now, do you understand why most of PCB boards are with green colors?

Though we know green is the most common one, but other colors such as red, yellow, blue, purple, black or some other colors are okay for us to make.

solder mask colors

If you have PCB board with a special color want to make, please contact us and we will try best effort to meet your request.  

You may also like

What kind of test for Coil Printed Circuit Board?

Wednesday, August 11th, 2021

In year 2019, one of our US customers asked us, Marina can Best Technology make a Coil PCB (Printed Circuit Board) with FR4 material? Yes, of course, we can make different kinds of PCB for our customer, included for the Coils PCB, which currently is widely used for wireless charging and antenna products. Please see the following Coils board from Best Technology.

The manufacturing process is same as other PCB manufacturing process, and just make sure the etching process and pay attention for the etching tolerance of the coils trace. And when coils PCB board finished, do you know what kind of test need to do to check the functional of Coils boards?

Today I would like to share how Best Technology test Coil PCB board. Everyone knows that we check the quality of PCB board with Flying probe tester, as the production efficiency is extremely low and the inductance and capacitance cannot be accurately measured. In this way, we need to use LCR meter to make verify the inductance and capacitance. See the LCT meter as following.

Best Technology chooses the digital meter LCR Meter to test the impedance characteristics of the coil. From the LCR tester you know see two numbers, one for inductance and another for resistance.

After test each coils printed circuit board, we will make record at our paper to make sure every measurement data will meet for customer requirement.

Currently, LCR Meter only provides a single-channel test function, and can only test the impedance characteristics of a set of coils at a time. But this is the effective test method for Coil printed Circuit Board. But we believe we will buy more LCR meters to let the test coil board become quicker.

If you have any comments on the testing for Coil printed circuit board, you are welcome to send us query and we are happy to discuss with you. You can visit www.bestpcbs.com to know more about us. Thank you

You may also like

What is E-Tester for Printed Circuit Board?

Sunday, July 11th, 2021

When the bare Printed Circuit Board qty become volume fabrication, the PCB manufacture will not use the Probe flying tester to test the PCB circuit board. Best Tech will make new PCB test fixture to test the bare PCB, The electrical Test (E-test), which is the final electrical test to verify net continuity and the absence of shorts on the bare printed circuit boards (PCBs). In Best Tech PCB factory, we perform 100% electrical testing on all bare PCBs its facilities as per IPC-6012 class 2 standard. And from the following photo in computer, you can see it will show PASS for PCB.

in test

in test

To test the PCB boards, we require the NETLIST file. Normally we create a reference netlist file from the customer’s original Gerber files during PCB fabrication.

We always prefer to receive the CAD file based on the netlist for comparison. Since a CAD based netlist is generated before PCB routing, it provides another layer of checking (against the Gerber files). This allows us to catch any PCB faults introducing in the event of an error in the Gerber files. For full turnkey PCB assembly (PCBA service) projects, this helps to ensure that the PCB boards are 100% correct before any components are populated.

tester 2

tester2

Here are Best Tech E-tester Capabilities

Minimum Continuity Resistance0.1 Ohms
Maximum Test Voltage1000 Volts
Max Isolated Resistance25 M Ohm – 2 G Ohm
Electrical Test Pitch (Fixture)20mil(0.5mm)
Electrical Test Pitch (Flying Probe)4mil
Debug /check for missing pins: (Test fixture)10 minutes
Test time per board:40 seconds
Setup time:30 minutes

All points are tested simultaneously. However, this process involves set-up to create the fixture itself and additional costs associated with the cost of materials.

The electrical test fixture has a limited shelf life and repeat using times. For every PCB it will need a fixture and its custom-made for a customer only. Many other factories only store 2 years shelf life for electrical test fixtures, but Best Tech will store at least 3 years for customer.

In order to ensure the quality of fixtures and spare enough space to store fixtures, Best Tech leaves one floor to keep the fixture. See attached fixture photo.

tester 1

tester1

During the 3 years’ time, customer no need to pay the fixture charge again if the update is no update. The flexible test fixture shelf-life policy, it will help customer save the cost.

At the end of the PCB production process, we use electrical test to check the interconnectivity of the PCB is correct against the original board data.

Best Tech did the E-Tester to test the PCB 100% before delivery to customer, this makes Best Tech get highly comments from our customer on the world with good printed circuit board quality and best service. See the customer highly comments of Best Tech.

customer highly comments on our service

customer highly comments on our service

You are warm welcomed to contact Best Tech to discuss about the Printed Circuit Board (PCB).

You may also like

What is IPC standard for PCB?

Monday, June 28th, 2021

Do you know what is IPC standard for PCB?

IPC, it is a trade association whose goal is to standardize the assembly and production requirements of electronic devices and components.  It was established in 1957 as the Institute of Printed Circuits.  IPC has developed thousands of standards and specifications to regulate the electronics manufacturing industry

IPC standards are related to PCB design, production technology, electronic assembly, etc., in order to achieve high reliability, high quality, high performance, and meet user specifications.

For PCB manufacturing, do you know which IPC standards are commonly used?

multilayer pcb

Here I would like to share you some standards which we mainly use:

  1. 1. IPC-6011: General Performance Specification for Printed Boards
  2. 2. IPC-6012: Appraisal performance and specifications for Rigid printed boards
  3. 3. IPC-6013: Appraisal performance and specifications for Flexible printed boards
  4. 4. IPC-6016: Fixed performance and specification of HDI or printed circuit board of high density interconnection layer
  5. 5. IPC-SM-840: Appraisal and performance of permanent performance
  6. 6. IPC-HM-860: Multilayer Hybrid Circuit Specification
  7. 7. J-STD-003: Solderable test for printed boards
  8. 8. IPC-A-600F: Acceptance conditions for printed boards
  9. 9. IPC-A-61: Acceptability of electronic components
  10. IPC-4761: Design Guide for Protection of Printed Board Via Structures

One of the most widely used industry standards in the manufacturing of printed circuit boards is IPC-A-610—Acceptability of Electronic Assemblies. … IPC-A-600—Acceptability of Printed Boards. This standard is used primarily for the incoming inspection of bare boards from a PCB fabricator.

In the IPC-A-610C document, electronic products are divided into level 1, level 2, and level 3. The higher the level, the stricter the quality inspection conditions. Here are how 3 levels divided:

Level 1 products: called general-purpose electronic products. Including consumer electronic products, certain computers and their peripherals, and products whose main purpose is to use functions.

Level 2 products: called dedicated service electronic products. Including communication equipment, complex industrial and commercial equipment and high-performance, long-life measuring instruments. Under normal use environment, this kind of product should not malfunction.

Level 3 products: called high-performance electronic products. Including high-reliability, long-life military and civilian equipment that can continue to operate. This kind of product must not allow any interruption failure during use, and at the same time, it is necessary to ensure the reliable startup and operation of the equipment in a harsh environment. Such as medical life-saving equipment and all military equipment systems.

resin filled production bpm20599

It is no problem for us to manufacture the PCB following the standard in IPC 6012 /6013 Class 2 and Class 3, as well as following to the standard listed above/

These acceptance conditions are the basis for the inspection of our company’s products, as well as the working standards of the employees at the production site, and also become an important part of the training of the employees for PCB production and assembly in our company.

Send us your PCB drawing, let’s help to make your PCB design into a real board.

You may also like

What is flying probe test printed circuit boards?

Wednesday, June 16th, 2021

Before leaving PCB manufacturing line, bare PCBs (Printed Circuit Boards) have to pass electrical tests so that it guarantee that boards go for high performance and high reliability after finish the SMT(Surface Mount Technology). Electrical tests are implemented to find out electrical and circuitry issues such as shorts, opens, resistance, capacitance etc. all of which indicate whether bare boards or assembled board are correctly fabricated.

shorts circuit

When test probes work, it moves quickly from test points to other test points as per instructions instructed by the computer set up program.  

probe flying test

Probe test is no need fixture, so it is very popular in the printed circuit boards manufacturing. The most significant reason is their cost. it is highly cost-effective for prototypes and low to mid-volume production. And the most important factor, the test reports can be provided for each board after finish tested and it is very easy to export from the computer, you can send to your customer very quickly for the test results of PCB.

Advantages of Flying Probe Test:

Low test cost (Eliminates fixturing costs and time)

Short test development time

Fast computer program development, easy integration of design changes

Rapid feedback provided to PCB design engineers at prototyping period

Process flexibility

Circuit access, even in the absence of test points

Controlled probe contact, programmable for any type of board

Different test solutions and approaches integrated in a single test system

Intrinsic positioning and measurement precision

Disadvantages of Flying Probe Test

Everything has two sides. Apart from obvious advantages, flying probe test have some disadvantages.

Since flying probes have direct physical contact with vias and test pads and small pits are easily caused on board surface, when flying probe tester is working on components without test pad, it’s possible that probes have contact with component leads so that loose leads or leads with badly-performed soldering may be missed.

In spite of the disadvantages mentioned, flying probe test is still regarded as a significant test method for PCB fabrication. Flying Probes have enhanced the competitive variable as lost time due to retooling has been removed. Prototype and Quick Turn product is the perfect match for Flying Probes as they carry out in low quantity orders and are quick to change jobs, unlike the long setup times with fixture testers.

By the way, to test circuit shorts, opens, Best Technology also do AOI checking to make sure there is no issue for PCB manufacturing.

AOI test

Contact Best Technology right now, to discuss more for printed circuit boards.

You may also like

Aluminum vs Copper Core PCB

Wednesday, May 19th, 2021

In Best Technology, currently the most common metal used for Metal Core PCB manufacturer are Aluminum, Copper. Today let’s talk about the main differences between aluminum substrate and copper substrate, hoping to help you choose the right substrate in future design projects.

Although they both share similar properties and functions, there are still a few variations between the two kinds of metals. Some of the key differences between aluminium and copper core PCBs are explained in the points below.

1. Thermal Conductivity

The thermal conductivity of copper substrate is up to about 400(W/mK) and the thermal conductivity of aluminum substrate is generally about 200W(W/mK). The thermal conductivity is higher, the transfer efficiency will be better, and the heat dissipation will be better, then the working life will be longer.

 Thermal Conductivity

2. Electrical Conductivity

Both aluminum and copper, being metals, are electrical conductors of electricity, although the exact degree of this varies between the two metals. When it comes to electrical conductivity, copper has a clear advantage over aluminum. In other words, in applications where there is a need for efficient electrical conductivity, copper makes for an ideal pick.

 Electrical Conductivity

3. Electrical Resistance

Resistance is very important when it comes to PCB design, as it can have an effect on the overall function and stability of the component. Given that copper has a higher density than aluminum, it tends to have a lower resistance than aluminum, so copper is an better choice where there’s a requirement for thinner circuits and faster electricity transfer.

Electrical Resistance

4. Weight

Since copper has the higher density for per unit area, the weight of copper PCB is much heavier than aluminum PCB for the same design.

In applications where light-weight construction is required more than anything else, aluminum is the preferred material of choice. On the other hand, applications where weight is not much of an issue, tends to be the ones where copper is widely used.

Weight

5. Application

Copper core PCB is the best heat dissipation among all MCPCB, so it’s mostly used in automobile headlights, taillights and some high-tech electronic products (unmanned aircraft, mining machine) high-power lighting equipment. The aluminum core PCB is mostly used in indoor lighting, energy saving lighting, street lighting and other energy-saving lighting electronic products.

Application
Application

In conclusion, due to the above different parameters and performance, the cost of copper is generally more expensive than aluminum. If you have other questions about MCPCB, welcome to contact us .

You may also like

How to Test for an Open Short Circuit on a PCB?

Tuesday, May 18th, 2021

Every printed circuit board need to do full test before ship to our customer. but you may have doubt, the PCB was made according to the original Gerber file, why finish the PCB production process, why the short Circuit will occur on a FR4 circuit board?

A short circuit may also occur during reflow soldering. the solder paste may accidentally connect two pins that are very close to each other. In some cases, errors can occur during the PCB design process because the wiring between different networks accidentally connects.

We believe every PCB manufacture have their own test method to do short circuit, but today I would like share how Best Technology to Check for Short Circuits in a Printed circuit board.

Here are some important steps:

Step 1 Visual inspection

The first step for locating short circuits on PCB is to carefully look at the entire surface of the PCB. Best Technology QC guys use a magnifying glass or low magnification microscope during the circuit board examination. We check the whole board surface to see if there are some traces break off. Any cracks or blobs of solder should get careful attention. Check all your vias. If you specified unplated vias, make sure that’s the case on the board. Poorly plated vias can create a short circuit between layers and leave you with everything tied to ground, VCC, or both.

visual inspection

All the testing work will carry out according to IPC 6012 class 2.

Step 2 Use a Digital Multimeter to find out where is the problem

To test a circuit board for a short circuit, you need to check the resistance between different points in the circuit. If visual inspection doesn’t reveal any clues as to the location or cause of the short circuit, grab a multimeter and try to track down the physical location on the printed circuit board. The multimeter approach gets mixed reviews in most electronics forums, but tracing your test points can help you figure out what isn’t the problem.

Step 3 use Probe flying Tester &E-tester

As long as you are in Printed Circuit board field, you are definitely known Probe flying test and E-Teter.

Flying probe test systems require no test fixture, it can serve both prototype and small production, providing maximum flexibility for PCB manufacturers and this job can complete in a short time.

probe flying test
probe flying test-1

But when your circuit board become to volume, you will need to open a test tooling/test fixture to test the Printed Circuit board to test the open short circuit.

E-tester

In my next blog in June, I will introduce Probe flying test to you in more detail.

If you have any question about printed circuit board, you are welcome to contact Best Technology.

It is our great pleasure to communicate with you for any issue for printed circuit boards.

You may also like

What’s fiducial marks on the PCB?

Saturday, April 24th, 2021

You may ever be recommended by some PCB manufacturers to add the fiducial holes on the board edge. Do you know what is fiducial marks and what’s the purpose for this kind of holes in a PCB?

Now, let me to show you something for what is the fiducial holes.

Fiducial holes, we also call it fiducials mark, while we assemble a PCB, it will need to locate the positions for each component, and it is positioned based on the fiducial mark as the reference point.

There are 3 types fiducial marks, first type is fiducial marks on a single board, second type is the fiducial marks on a PCB panel, third one is the fiducial marks for some single component on the board.

Here are the pictures for you to understand the types of the fiducials.

Fiducial holes types
Fiducial holes

Fiducial mark on a single board is designed for positioned all circuits features on a single board. It is necessary to have a fiducial mark on a single board.

And fiducial marks on a PCB panel is used to assist positioning the circuits. 

For the fiducial mark of a single component, it is designed to position the fiducial mark of a single component, which can improve the placement progress (For QFP, CSP, BGA and other important components must have the fiducial marks).

So, it is important to add the fiducial holes on a PCB board.

Also, while we make the panel for the PCB board, on the diagonal of the four corners, it is required to have 2 fiducial points at least on 2 diagonal corners.  you can also place 4 marks on the four corners, but generally, assembly plant will only need 2 marks for recognize.

See below a PCB panel for reference:

PCB panel drawing Best Technology
Fiducial holes on a panel

In the other hand, while you design the PCB, please try not to put the silk screens, pads, traces etc. within 2mm of the optical fiducial marks. Otherwise, the SMT machine will not be able to recognize the optical fiducial on the PCB boards.

And if you add the fiducial holes on the area which without any circuits, to avoid the holes being etching while the process, so generally we suggest to add a metal circles around the fiducial holes, to make it more obviously on the boards.

If you have any new PCB design which you also want to add the fiducial marks.

You are welcome to contact Best Technology for a help and we will show our best help for you.  

You may also like