Category Archives: PCB - Page 3

PCB outline processing technology

Posted by on July 20, 2010 No comments

People Who engaged in printed circuit board processing, will be understanding: PCB outline processing is one of the difficulties of the whole PCB processing , most PCBS ARE a rectangle outline, but also a considerable number of PCB with special outline.

Please see the below four PCB outline processing methods:

1. Milling outline: PCB outline processing by CNC milling machine, we should be provides the data of outline and the corresponding hole, and it will be input by programmer. As not so much distance between PCB puzzle, usually about 3mm, so mills generally 3mm in diameter, or 2.4mm. First milling drill hole on the plate, then fixed the PCB and plate, last milling outline.

2. Punching outline: Need to setup mold, then punching outline, correspond the PCB positioning pin and the positioning hole, generally choosing 3.0mm hole as positioning hole.

3. Open “V” groove: Using “V” groove cutting machine along the PCB design “V” slot cut into the PCB parts connected to each other;

4. Drill outline: Using drill machine to drill holes through outline. Normally open “V” groove and drill only for processing assistance.

CMD Circuit specilizing in making high quality printed circuit boards and flexible circuits. Please contact us to know more.

Exposed copper of HASL analysis and treatment

Posted by on June 21, 2010 No comments

As you know, the HASL is the most popular PCB surface treatment,exposed copper maybe be coursed by this method.

HASL is that input the PCB in molten solder (63SN/37PB), then use hot air to blows off the excess solder in the surface and metal-based inner hole of printed circuit board to get a smooth, uniform and also bright solder plated layer. After HASL surface treatment of printed circuit board the plated layer should be bright and uniform integrity, good weldability, without nodules and half-wetting,plated layer is complete no exposed copper.

After HASL, pad surface and the metal-based inner hole are exposed copper is an important test of finished product defects, also is the one of main reasons of HASL rework. please see the below several reasons for exposed copper:

1. Pad surface dirty, contaminated with residual solder pad.
2. Pre-treatment is not enough, coarsening bad.
3. Flux activity is not enough.

We should control the technology of exposed copper of HASL surface treatment, reduce the Rework and poor circuir boards, ensure the quality of products.

PCB to prevent warping

Posted by on June 19, 2010 No comments

How to prevent the PCB warping? This is the most improtant in the PCB manufacturing preocess.

1. Why is flat circuit board requirement

In the automation plug line, if PCB isn’t flat will cause mispositioning, components can not plug in to the board of the hole and surface mount pad, and even crashing automatically installed machine. After components installed on board, component pins are difficult to cut neatly. Board can not be fitted to the chassis or the machine’s outlet, so, board assembly factory is also very troubled.

2. Warpage standards and test methods

According to the U.S. IPC-6012 (1996 Edition) <<Rigid Printed Boards and performance specifications>> for the maximum allowable surface mount PCB warpage and distortion of 0.75%, other 1.5% of various board permitted. Compare to IPC-RB-276 (1992 Edition) to improve on the requirements of surface mount PCB. Currently, the electronic assembly factory agree with, regardless of double or multi, 1.6mm thickness, is usually 0.70 to 0.75%, and for SMT, BGA’s board, demand is 0.5%.
 
3. Warping board processing:

As in our factory, PCB in the final test will be 100% flatness inspection. Failure of the board who will be singled out, into the oven at 150 degrees and bake under the weight of 3 to 6 hours, and under the weight of natural cooling. And relieving the board out, check in for smoothness, this would save parts of the board, some boards need to bake for two to three times the pressure to leveling.

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.

PCB surface treatments

Posted by on April 14, 2010 No comments

Bare copper itself is very good solderability, but is easily exposed to air oxidation, and susceptible to contamination. This is also the PCB surface treatment must be the reason.

1. HASL
Hot-air solder leveling. The most common PCB surface treatment menthod. Lead and lead-free should be considered.

2. OSP
Organic solderability protective coating (OSP, Organic solderability preservative) is an organic coating to prevent oxidation of copper in the welding before, that is to protect PCB(printed circuit board) pad solderability from destruction.

3. ENIG
Nickel Immersion Gold. The copper surface is plated of Ni/Au. The deposition thickness of the inner Ni layer is generally 3~6um, the deposition thickness of the outer Au thin, usually 0.05 ~ 0.1um. Ni as the barrier layer between Cu and soldering tin. Welding, outside Au in the solder which melts rapidly with soldering tin and then turn into Ni/Sn intermetallic compounds with inner Ni. The gold-plated to prevent Ni oxidation during storage or passive, it should be enough gold plating density, the thickness can not be too thin.

4. Immersion Silver
Immersion silver process through the thin (about 0.1~0.4um) and dense to provide a layer of silver deposited organic protective film, the surface of the silver with the greatly extended life. Immersion Silver surface is very flat and very good with weldability.

5. Immersion Tin
Only used for two reasons for immersion tin process: first, the surface is very flat, coplanarity good; the other is lead-free. But in the immersion tine process easy to be with Cu/Sn intermetallic compound, Cu / Sn intermetallic is with poor solderability.

These are five main PCB surface treatments, since each have their own unique surface treatment technology, application is not quite the same.

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.

The knowledge of via in PCB

Posted by on November 4, 2007 No comments

As is known to all, via in PCB is full of pad, and connect the traces of two sided. via is the most improtant part of mulitylayer PCB.

Simply speaking, every hole on printed circuit board(PCB)  may be called via.

We can divide vis into two types in function: firstly, used for electro-connection among layers; secondly, used for fixing components. We also divide it into three types in technology: buried via, blind via and though hole.

Buried via is connecting holes which are located in the inner layers of the PCB and won’t extent to the surface. Blind via is connecting the inner layer traces with the top and bottom surfaces of the PCB. Through hole goes through the whole PCB, which is used to realize inter-connection or used as components mounting position hole. Due to the simple technique and low cost, most of PCBs use it rather than the other two via.

Now you can know the via in PCB well, for further information, please don’t hesitate 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.

Pages: Prev 1 2 3 4 Next