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PCB silk screen plate making process

Posted by on September 25, 2010 No comments

Please see the below  PCB silk screen plate making process:

1.Stretching

Stretching steps: network clean – the level of calibration – the bottom of plastic coated – Pop – Tension Measurement – coated adhesive – the net, Edge – Storage.

2.Drying net

Wash Network – Drying – use of premium film method – using light-sensitive adhesive (net pulp) – the choice of mesh lines – Film’s choice – exposing – Pressurized water wash and dry – use blue oilto cover – inspection, repair network, write the date of completion and the corresponding number and record keeping, storage.

3.Storage

Storage has generally adopted a vertical storage, network framework can be made or purchased, should be stored in the same environment with the screen environment to prevent deformation, while the screen before the need to test the tension on the screen, and test by the photographic film .

Silk-screen production steps

Posted by on September 20, 2010 No comments

This time follow me to know the silk-screen production steps, how to mak e the silk-screen of printed circuits boards.

First, wash silk-screen

* Items required for washing silk-screen:
1, stripping water;
2, diluent;
3, detergent.

Second, coating

* Required coating materials: photoresist, scraper bucket, frame net sets.

Third, how to prepare light-sensitive adhesive.

Fourth, exposure.

Last, develop, wash csreen, drying and repair.

These are the silk-screen production steps, CMD Circuits has many years of experience of making printed circuit boards. Please contact us to know more.

PCB testing

Posted by on September 14, 2010 No comments

This time let’s to talk about the PCB testing. When the printed circuit boards are finisehd, we should test PCB for short or open circuit condition, we can use optical test or E-test way to test.

Optical test methods identify defects in each layer by scanning, the electronic testing is usual using Flying flying-probe to check all connections. E-test for short circuit or open circuit much more accurate, but the optical test can more easily detect incorrectgap problems between conductors.

CMD Circuits have the very strict quality control and testing machines, please don’t worry about the quality of our circuit boards.

The shortcomings of FPC characteristics

Posted by on September 7, 2010 No comments

As your know, Flexible circuits(FPC) provide major benefits over rigid circuit boards, but they also have the shortcomings. Please see below shortcomings of FPC Characteristics:

1. Small mechanical strength,easy to crack;
2. Difficulties in process design;
3. The possibility of re-processing is low;
4. The difficulties for checking;
5. Can’t Carrying heavy parts for single one;
6. Easy to break, beat, wound;
7. Higher cost of the product.

Althrough FPC have these shortcomings, but now more and more widespread use of Flex circuits, more and more advanced technology. We can develop the strong points and avoid the weak points and provide quality goods at competitive cost.

Flexible circuit substrate thickness

Posted by on September 3, 2010 No comments

This time let’s to see the several kinds of based flexible circuit substrate thickness, & then you can see which is the best suitable for you.

1. Coverlayer of flexible circuits:

1). 12.5um: PI:12.5um; adhesive:15um; total thickness: 27.5um
            PI:12.5um; adhesive:25um; total thickness: 37.5um
2). 25um:   PI: 25um;  adhesive:25um; total thickness: 50um

2. Substrate thickness of flex circuits

1).Single RA copper:

18/12.5UM: copper thickness:18um; PI:12.5um;adhesive:13um; total thickness 43.5um
35/25UM:  copper thickness:35um; PI:25um; adhesive: 20um; total thickness 80um

2).Double-sided RA copper:

18/12.5UM: copper thickness:18um; PI:12.5um; adhesive: 13um; total thickness: 74.5um
35/25UM: copper thickness:35um; PI:25um; adhesive: 20um; total thickness: 135um

I think we have all of your required thickness, we haven’t any problem to product it according to your requirements. OK, if you need further information of flexible circuits(flex pcb), please contact us feel free.

PCB substrate CCL

Posted by on July 27, 2010 No comments

This time let’s to know the PCB substrate CCL. CCL also known as the PCB substrate. The reinforcement material impregnated with resin, one or both sides covered with copper, made by hot pressing into a  plate material, as copper clad laminates.

It is to do the basic PCB material, often called the substrate CCL. When it is used for multilayer circuit board production, also called core board (CORE).

FR-4 —- Flame Resistant Laminates,our material is now commonly used FR-4, also the most popular used for substrate.

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.

Flexible Circuits Price

Posted by on July 3, 2010 No comments

Almost all the electronics factory purchasement staff have been confused about the changing price of flexible circuits, even if some have many years of experience in the purchasement of flexible circuits  staff has not totally understand the causes. In fact, the price of flexible circuit board by the following multi- factors:

1, flexible circuit boards of the multifarious price caused by different material;
2, flexible circuit boards used in the different production process caused by the multifarious price;
3, the difficulty of flexible circuit board itself caused the multifarious price;
4, customer different requirements will result in different prices;
5, different flexible circuit board manufacturers will course multifarious price;
6, different method of payment of price will course multifarious price;
7, different regional also will course multifarious price.

You can see the above main seven factors consist of flexible circuit boards price. If you have an inquiry about the flexible circuit boards, please don’t hesitate to contact us, we will offer you the very competitive price.

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.

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