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Multilayer PCB Production Process

Posted by on May 12, 2010 No comments

If you want to know more details of the PCB production process, now please see the below form of our multilayer pcb production process for you study.


CMD Circuits has a very strict quality control system to ensure to make high quality products.

Why to use high Tg PCB Material?

Posted by on April 20, 2010 No comments

First of all, talk about the high Tg refers to the high heat resistance. With the rapid development of electronic industry, especially on behalf of computer electronic products toward the high function, high-rise development, require higher PCB material heat resistance as an important guarantee. With SMT, CMT represented by the emergence of high-density mounting technology and development, and the PCB in the small hole size, fine lines, thinner, the more inseparable from the support substrate with high heat resistance.

PCB materials under high temperature, not only produce softening, deformation, melting and other phenomena, but also in the mechanical, electrical characteristics of the sharp decline (I think we do not want to see their products occurred).

So the general high-Tg FR-4 and the difference between the FR-4: In the thermal state, especially in the heat after absorption, its materials, mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition , thermal expansion differences in various situations, high Tg products significantly better than the common PCB materials. This is why to use the high Tg PCB material.

the whole thickness of FPCs

Posted by on March 13, 2010 No comments

Now I want to introduce the wholes thickness of FPCs. As is known to all, there are four kinds of FPCs(flexible circuits): single-sided FPC, double-sided FPC, dual access FPC and multiayer FPC. Let’s see the thickness of single-sided and double-sided FPC as examples:

(!) single-sided FPC

The constructure of single layer FPC is as follows:

25um+20um+35um+20um+25um=125um≈0.12mm

Note: the thickness of adhesive changes according to the thickness of Cu. For 1/2, 1/3 OZ Cu, we usually use 12um adhesive. But for 1OZ Cu, we have to use 20um adhesive.

That’s according to the common material. If we want the board to be thinner, we also can use the adhesiveless material to make the board about 0.60mm thick.

(2) double-sided FPC

Double sided FPC means there are two layer of traces in the FPC.

The constructure of double sided FPC is as follows:

25+12+35+12+25+12+35+12+25=193um≈0.20mm

Now you have an idea about the whole thickness of the FPCs, if you need more information, please contact us anytime.

Copper foil features of flexible circuits

Posted by on January 12, 2010 No comments

Here, let’s to know the more details of copper foil is used in the flexible circuits. The cooper foil is very improtant part of flexible circuits.

1. There are two kinds of copper foil:
1>. rolled annealed copper foil(RA-copper)
2>. electrodeposited cooper foil(ED-copper)

2. The thickness:
1>. normally use 1/3oz, 1/2oz,1oz and 2oz four kinds;
2>. RA-copper: 1oz, 1/2oz, 1/3 oz or less thickness, but higher cost.

3. flexibility:
Rolled annealed copper foil is of high strength and can stand bending, two times for electrodeposited cooper.

Now, I think you know the Copper foil features of circuit boards more details. Ok, if you need more information, please do feel free to contact us.

Printed Circuit Board Technology

Posted by on November 11, 2009 No comments

Semiconductor continually refined reduction techniques, many of the original packages need to use more discrete components in order to constitute the circuit, but now live can use a highly integrated chips to replace, so some people gradually bearish printed circuit board technology. Theory is true, but the actual development is at odds with the theory of … …

Some people believe that printed circuit board (known as the Mainland of China: printed circuit) technology will become increasingly important, mainly because there is a 2:1, with the semiconductor process technology continues to improve, which requires multiple chips can be achieved effectiveness of, and now stars as long as the 1,2-integrated chip can be completed, as in the past need chipset (Chipsets) circuit can be achieved, but now available SoC (System-on-a-Chip; SoC) to achieve, so so that the number of wiring between chips declining.

Another reason is to speed up data transfer between chips, past parallel-type transmission interface is constantly being replaced by serial transmission interface, today’s high-speed serial multi-frequency approach includes mining can enjoy quickly transfer data, and the than those without parallel transmission crosstalk (Crosstalk) problem. For example, ATA into SATA, PCI into PCIExpress, SCSI into SAS, RapidI / O parallel version of the serial version of the conversion … so are examples.

So we should consider the printed citcuit board technology is also very impotant, we can’t leave it in our life.

Flexible Circuits Applications

Posted by on August 10, 2009 No comments

Flexible circuits can be used in many applications as the benefits of flexible circuits in many industries.

Highly automated fabrication methods, these ways can reduce workers handling of the flex circuits, reducing both cost and probability of error. Applications like cameras, printers, disk drives, and automotive panels.

High accuracy circuits is to handle ultra-fine lines and tight tolerances in an age of miniaturization. Such as used in aerospace and medical applications. Flexible circuits applications are most used in many industries including:

·Personal and mainframe computers, disk drives, and printers
·Automotive radios, cassette players, electronic control systems and on-board computers
·Telecommunications equipment, telephone handsets, and switching systems
·Consumer electronics like calculators, stereos, cameras, and compact disk players
·Heart pacemakers, hearing aids, and other medical applications.
·Jet engines, navigational and flight control systems
·Industrial controls, machine tool controls, and robotics

What are the benefits of using flexible circuits?

Posted by on December 17, 2008 No comments

What are the benefits of using flexible circuits? Flexible circuits provide below major benefits over rigid circuit boards.

1>. A solution to a package problem;
2>. Reduce assembly costs
3>. Replacement for a circuit board and wires;
4>. Reduce weight and space;
5>. Dynamic Flexing;
6>. Thermal management/high temperature applications;
7>. Aesthetics.

So most designers choice the flexible circuits for most applications.

The performances of flexible circuits

Posted by on August 6, 2008 No comments

This time let’s to know the performances of flexible circuits.

(1) Base material:
PI(Polyimide) is the most common used, which is a kind of macromolecule material of high temperature proof and high strength, invented by Dupont. The polyimide made by Dupont is called Kapton. Besides some polyimide made in Japan can also be found. Its price is much lower. Polyimide can bear 10 seconds of high temperature of 400 degree centigrade. Its tensile strength is 15,000~30,000 PSI. The base material with 25um thickness is the cheapest and the most popular one. If we need the circuit board to be more rigid, we should choose 50um. Otherwise, if we need the circuit boards to be more flexible, then choose 13um.

(2) Adhesive:
It is divided into epoxy resin and polyethylene, they are all thermosetting adhesive. The polyethylene’s strength is lower. If we hope the circuit boards to be more flexible, then choose polyethylene. The thicker the base material and the adhesiveon it is , the more rigid the circuit boards are. If the circuit boards have to be bent in a large area, we should choose thinner base material and adhesive so as to reduce the stress on the surface of the copper, then lower appearance of micro crack.

(3) Copper:
It is divided into rolled annealed copper foil and electrodeposited cooper foil. Rolled annealed copper foil is of high strength and can stand bending, but its price is higher. Electrodeposited copper foil is much cheaper, but of low strength, easier to be bent.

When we choose to use rolled annealed copper foil, we should pay attention to the direction of the copper. The direction of the copper has to be the same with the bending direction of the circuit boards.

(4) Coverlay with adhesive:
25um coverlay would make the circuit board more rigid, but it is cheaper. Therefore to the circuit board needing to be bent greatly, we’d better choose 13um coverlay.

The adhesive is also divided into epoxy resin and polyethylene. The FPC using epoxy is more rigid. After thermosetting, there are some adhesive squeezed out at the edge of the coverlay. If the soldering pads are larger than the hole on the coverlay, the adhesive squeeze out would reduce the size of the soldering pads and lead to irregular edge. Therefore, we’d better choose 13um adhesive.

These are more details about the performances of the flexible circuits. If you still need more information, please do fell to contact us.

Circuit boards Electrical testing methods

Posted by on July 3, 2007 No comments

This time let’s talk about the electrical testing methods of circuit boards, there are: Dedicated,Universal Grid,Flying Probe, non-contact electron beam, conductive cloth (plastic), Capacity and ATG-SCAN MAN), of which there are three most commonly methods:Dedicated,Universal Grid,Flying Probe.To better understand the functions of various equipmenst, the following will compare the characteristics of three major methods.

1. Dedicated test
The reason for the specific type, mainly because they use fixtures only applies to one material number, different number of board material can not be tested and can not be recycled. Test points, the single panel in the 10,240 points, 8,192 points within each two-sided test can be made, the density in the test, because the probe head and the thickness of the relationship between the pitch used for more than the board.
2. Universal Grid test
The basic principle is the Universal test circuit PCB layout is based on the grid (Grid) to design, generally refers to the so-called grid line density,while the Universal test is based on this principle. Therefore making the fixture simple and fast, and explore needle can be reused.Universal test points is usually more than 1 million points.
3,Flying Probe test
Flying Probe test principle is very simple, only needs two probes for x, y, z movement to each of the two end points of each line tested, so no additional production of expensive fixtures. However, as is the end-point test, so very slow speed, about 10 ~ 40 points/sec, more suited for samples and small circuit boards production.

If you need more information of flexible circuits and printed circuit boards, please don’t hesitate to contact us.

PCB board electrical testing Introduce

Posted by on March 2, 2007 No comments

PCB board(printed circuit board) in the production process, will inevitably cause defects on the electrical due to external factors, such as short circuit,open circuit and leakage power, coupled with continued in the high PCB density, thinner pitch and multi-layer evolution, if failed to be screen out defective boards, and allowed to flow into the manufacturing process,the cost will inevitably cause more waste, so in addition to improved process control, improve the testing technology for the PCB manufacturer can also provide reduce scrap and improve product yield solutions .

In the electronics manufacturing process, due to the cost of the damage caused by defects in various stages of varying degree, the easier it will lower the cost of remedy. “The Rule of 10’s” is a commonly used to assess the process at different stages of PCB was found to be defective when the cost to remedy. So PCB board E-testing is the most improtant.

In the PCB manufacturing process, there are three stages to be tested:
1, inner layer etching
2, after etching the outer line
3, finished

Each stage usually 2 to 3 times the 100% testing, screening out bad board for further re-processing. Therefore, the PCB board E-testing is also a question of process data collection point, the best source, by the results, get open circuit, short circuit and other insulation of the percentage for rework inspection, the use of quality control methods to find root of the problem to be solved.

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