The knowledge of printed circuit board via

                                     via

                                  The basic definition of via

As is known to all, via is one of the important parts of multilayer PCB. The cost of drilling usually makes up 30%~40% of the cost of PCB manufacture.

Simply speaking, every hole on PCB may be called via.

Functionally, via can be divided into two types: firstly, used for electro-connection among layers; secondly, used for fixing components.

Technically, it may also be divided into three types: blind via, buried via and though hole. Blind via is located on the top and bottom surfaces of the PCB, deep and used for connection of top traces with the inner layer traces below.

Buried via is the connecting hole which is located in the inner layer of the PCB and won’t extent to the surface.

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.

2010 Spring Festival Notice

In the past 2009, although the word have went through economical crisis, we still have great achievement. We should take this opportunity to thank our friends, customers, suppliers, colleague, and everyone supporting us in 2009.

Now it’s time to back home to enjoy the merriness of get-together with family, friends, the one you loved and beloved. Here are our Lunar New Year (Spring Festival) holiday arrangement:

Feb 7th~Feb 21st, 2010: Closed

Feb 22nd, 2010: Re-open

You can contact our sales representative to discuss everything, but samples, or manufacturing will stop. Our guys is anxious to back home every hour. ^_^, we think you should understand that. ^_^

Thanks everyone and wish business in 2010 will be much more prosperous.

Enjoy the happiness of everyday!

Yours Sincerely,

Best Technology Staff

www.bestfpc.com

The basic knowledge of PCB(3)

Today we will continue expanding some basic knowledge of PCB:

3. Components encapsulation technology

(1) Through hole technology

It means we mount components on one side, and solder the pins on the other. The disadvantage of it is space consuming. In fact, theirs pins take up space of both sides. While the advantage of it is good construction, which can bear pressure.

(2) Surface mounted technology
it means pins are soldered on the same side as components. We don’t have to drill holes  on PCB and don’t have to solder every pin. The advantage of SMT is that the components are more compact and cheaper than those in THT.

                                                smt2 

4. Gerber files:

Usually it comprises the layout plan of signal, ground, power, solder mask, silk screen, and drilling layout plan, etc.

                                          gerber file

5. Manufacture steps
choose base material, then use subtractive transfer to show the artwork on metal conductor.

The above explanation is only the most basic   information, if you want to know more, please to go our website: http://bestpcbs.com/products or contact me at Iris@bestfpc.com.

We are happy to help you clear all your questions!!!

The basic knowledge of PCB (2)

2. The classification of PCB

 (1) Single sided PCB

Single sided board means the conductor pattern appears only on one side. Because single sided PCB has many strict limits. On trace design, only circuit at early stage use this kind of boards.

(2) Double sided PCB 

Double sided board means the conductor patterns appear on both sides of the board. However if we use the conductor patterns on both sides, there should be proper circuit to connect two sides. The bridge between the circuits is called via. Those vias are plated with metal, such as tin, copper, gold, etc. Because the area of double sided PCB is two fold of the area of single sided, and the conductor pattern can cross with each other, so it suits to be used on more complex circuits.

(3) Multi-layer boards

In order to enlarge the area of conductor pattern, multilayer PCB uses more single or double boards. It uses several piece of double sided boards, and a dielectric layer is put between every layer of boards. The layers of one PCB represent the layer of conductor patterns. The amount of the layers is always even number. Technically we can make PCBs up to 100 layers.

 For via, if we use it on double sided PCB, the whole boards will be drilled. While on multilayer PCB, if you just want to connect some traces, via may will waste trace space of some layers. Then we use buried vias and blind vias to solve this problem, because they are only drilled through several layers.

a. Buried vias only connect inner PCBs, so we can’t see them from the surface.

b. Blind vias connects several layers PCB with surface PCB.

In multilayer PCB, the whole board directly connects the ground line and power (used for preventing affection of the transmission signals on the signal). So we divide layers into signal, power, or ground. If the components on PCB need different power supply, this kind of PCB would have more than two layers of power and wire layers.

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The basic knowledge of PCB

I saw some basic knowledge about PCB, today I summarized it and I want to share with you now.

1. Definitions:

For standard PCB, it is the combination of bare board and components on it. While for bare board PCB, it is called printed wiring board. We usually call it PWB.

(1) Traces:

The base material of PCB is comprised of dielectric, heat insulation, uneasy to bend materials. On its surface, we can see thin traces, its material is copper. Originally the copper covered the whole PCB. Parts of it were etched during the process of production. Those parts left become net-like thin traces, which are called conductor pattern, and are used to provide circuit connection for components on PCB.

(2) Name of two side:

On most common single sided PCB, components are on one side, conductor pattern is on the other side. Then we would need to drill holes on the board, so that pins can put through the board to the other side. Therefore, the both sides of PCB are called component side and solder side.

(3) Gold finger:

Gold finger is functioned to connect two PCBs. We usually insert the gold finger of one PCB to the proper slot of the other PCB. 

(4) Solder mask and silk screen:

The green or white oil on PCB is called solder mask, which is functioned as dielectric protective layer, can protects copper traces and also can prevent components to be soldered at incorrect place.

On the dielectric layer, a layer of silk screen will be printed. Some words will be printed to show the position of those components. It is also called legend.

FPC Application Market Analysis

The market of FPCs applied on hard disk still can secure a place, although its growth rate is lower. The speed of NAND replacing the hard disk won’t be so fast. At present in the times of information explosion, the quantity of storage increases rapidly. The hard disk can corresponds very well. However NAND doesn’t work. Although NAND’price reduces quickly too, it can’t match the increasing speed of mainstream storage density. There are only 6 manufacturers of hard disks, and the quantity will reduce; while the number of FPC manufacturers is much larger. They have little space to discuss the price. Meanwhile, the patterns of FPCs needed for hard disk are so unitary. All of those determine that the growth of FPC in hard disk market is strong.

The situation in optical drive industry is similar to that in  hard disk industry, thanks to the increase of Blue Ray. The market of FPC in printer is also relatively stable. The electronics of automobiles is obvious too. On the occasion of using ECU, FPCs are always needed. They are of high reliability and space superiority.

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FPC Application Market Analysis

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flx24       As the development of high technology products, FPC becomes more and more popular. Its application becomes wider and wider. Therefore, let us analyze its market prospects.

 Industry research institute Shuiqingmuhua published “global and China circuit board industry research report of 2009”. The FPC industry emerged in 2002, developed very quickly in 2003 and 2004, and went into the stage of price struggle. In 2006 and 2007 the FPC industry has been in downturn, however in 2008 it began to recover. Even the economy crisis didn’t get in the way of the recovery of FPC industry. On one hand, the price reduction stimulates the demand of FPC; on the other hand, the demand for lighter, thinner, shorter, smaller and high reliability products also creates the room of using FPC. At the same time, the FPC manufacturers which went through price struggle and survived had all faced great pressure. They have already been familiar with the cost control and dealing with stress, and won’t be afraid of the arrival of economy crisis. Cell phone is the critical motive for FPC market enlargement, especially intelligent cell phone and high-end cell phone. The growth of consumer electronics field is also favorable. In consumer electronics such as notebooks, PND, digital camera, DV, LCD TV, plasma TV, media player, frequency of using FPC will increase as its performance and its strive for ultra-thin volume. Notebook and flat panel TV use LED backlights a lot. FPC is the most common used way in which LED connects to the main circuit. Even in 2008 and 2009 it still has great potential to grow. The swing joint between notebook screen and motherboard has great probability of using FPC. (Continued)

How to calculate the thickness of FPCs

As is known to all, the FPCs are divided into single layer, double layers, dual access, multiayer and flex rigid.

Now I want to introduce the basic method of calculating the thickness of FPCs.

(!) single sided FPC

The constructure of single layer FPC is as follows:the board thickness for single sided FPC

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 0.8mm 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:

the board thickness for double sided FPC25+12+35+12+25+12+35+12+25=193um≈0.20mm

The advantages and disadvantages of FPC

A: Disadvantages:

1. Original cost is high

Because the FPC is designed and made for special application, the cost of circuit design, wiring and photographic plate is high. Except special need, we’d better not use them.

2. The modification and correction is difficult

Once FPCs are made, if we want to modify, we have to begin from the base drawing or gerber program. Therefore it’s difficult to change. On its surface there is a coverlay. Before the modification, we have to remove it, after the modification, we have to recover it, which is difficult.

3. Dimension limitation

Since FPC is not popular, we usually use intermittent method to make them. Then we can’t make too long or wide FPC with the limit of manufacture instruments dimensions.

4. Easier to be damaged if improper operation

It is easier to cause the damage of FPC circuits because of improper operation. Special trained workers are needed in tin plating and rework

 B: Advantages

FPC is the printed circuit board which is made of flexible insulating base material. It has many advantages many rigid PCBs don’t have.

1. It can be bent, rolled, folded freely, can be arranged randomly according to the space, can be moved and stretched in 3-D space, then integrate the components assembly and wiring connection.

2. It can satisfy the need of electronic products to develop in the direction of high density, smaller size, higher reliability, since FPC can greatly reduce the volume and weight of electronic products. Therefore FPC is widely applied in fields or products of aerospace, military, mobile communication, laptop, computer exterior design, PDA, and digital camera.

3. FPC also has the advantages of good thermal diffusivity and solderability, easy to assembly, low combined cost. The design of rigid-flex boards also make up the disadvantage of components carrying ability of flexible base material.

FPC Application

At present, the most important consumer electronic product promoting the development of FPC is mobile phone. There is a large quantity of FPCs used in cell phones, such as the cell phone keyboard, battery, display screen, display components, and motherboards.

 The second most important is LCD. LCD is divided into categories such as TN, STN and TFT. TN type LCD is applied in black and white display products, such as calculators and electronic watches; STN is mainly applied in colorful display products; TFT is mainly applied in medium-big flat panel display, such as notebooks, LCD Monitor, LCD TV. Due to the stable growth of those consumer products in recent years, FPC also grows stably. Its market and manufacture is mainly distributed in Japan. The combined growth rate of the IC substrate market in 2001~2006 promotes the corresponding growth of FPC.