some basic knowledge about PCB

some basic knowledge about PCB

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

1. Definitions:

For standard board, it is the combination of bare board and components on it. While for bare board PCB, it is called printed wiringboard. 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 onPCB.

(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.

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 onboth 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.

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.


4. Gerber files:

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


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




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Printed Circuit Board History | Printed Wiring Board

The history of printed circuit board, wiring board and PCB all describe a device that provides electrical interconnections and a surface for mounting electronic components. Although ” wiring board” is more technically correct, the term “printed circuit board” (PCB) is most commonly used.
The printed circuit board history begins with the first patents describing the “printed wire” were issued in 1903, PCBs as we know them came into use after World War II. Dr. Paul Eisler, an Austrian scientist working in England , is generally credited in history with making the first PCB. The concept was to replace radio tube wiring with something less bulky.
In the 1950s and ’60s, the history of PCBs evolved to circuitry on one side (single-sided) were the dominant variety. Still in use today, single sided boards are the simplest variety of PCB.
PCB’s history in the ’60s and early ’70s, lead to processes that were developed for plating copper on the walls of the drilled holes in circuit boards, permitting top and bottom circuitry to be electrically interconnected. These double-sided boards became the industry standard. Used today in consumer products and computer peripheral equipment, double-sided boards are slightly more expensive than single-sided boards.
As the densities and complexities of electronic components increased, the multi layer circuit board a process of sandwiching several circuitry layers together was developed. By  the mid 1980s, the history changed to multi layers accounting for the majority of Printed Circuit Boards produced in the U.S. Today’s computers, aerospace equipment, and instrumentation and telecommunications gear all contain multi-layer boards.
The history of the printed wiring board or now referred to as the printed circuit board has evolved over time to become the leading method of electronics in just about everything we use and buy.
Kingford is proud to be a part of PCB history and proud to be the preferred supplier of multi layer printed circuit boards and printed circuit boards for industry leading OEM’s and Electronic Contract Manufacturers serving the Industrial, Medical and Instrumentation markets since 1999.

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PCB Market Europe And The United States


Europe and the United States is weak, weak consumer demand for electronic products, the impact of the traditional PCB season, look forward to the second half of the year, Apple new models innovation, coupled with major brands to steal the end of the season, will continue to pour soft board, carrier board and HDI board needs ; Therefore, the overall PCB industry in the second half of the year, “eat soft do not eat hard”, soft board, load mills and revenue is expected to continue to grow up.

Hand-held intelligent products with strong demand for flat-panel computers, printed circuit board (PCB) manufacturers are exposed, especially HDI, soft board and other manufacturers in August reported better news. (2367) also has a history of the next high level, the performance is quite bright, legal person said that due to the end of the major companies will be the first to be ahead of the first quarter of the year, The introduction of new models to seize the business opportunities, and because of smart phones, tablet computers are widely used HDI, soft board and other products, the group is expected to remain bright in the second half of the results.

In the second quarter in the PCB manufacturers, the most outstanding performance of the soft board, revenue growth of about 15-20% over the previous quarter, as the carrier board is affected by the impact of the earthquake, the quarterly increase of about 6 to 7% (8046) benefited from the CPU carrier board to improve the yield, mobile phone customer orders increased, driven by the CPU carrier board and packaging board growth, but also drive the gross margin back to temperature; but the other side of the hard board factory Jian Ding (3044) by the PC, TV sales as expected, the impact of photovoltaic panels and other product lines, the overall performance of PCB hard board factory as soft board.

(6269) EPS to 2.79 yuan to win, a record high record, Jia Lianyi (6153) after-tax net profit of 591 million yuan to earn the most, while the Asahi Soft (3390) consolidated gross margin up to 30.56% ranking first, but the other side Yi Jia (2402) due to output efficiency and poor yield under the drag, the loss of the dilemma, the first half of the loss of 0.69 yuan per share after tax.

In fact, the soft board industry has been oversupply in the past, so there speculative competition, but since last year, thanks to smart phones and other commodity demand warming, performance gradually shine this year, become the PCB industry, the most watched ethnic groups, even the (8213) in order to expand the product line, also decided to enter the main ring (3267), as Taiwan Table Branch (6278) also continued to invest with the Thai.

Legal users said that not only Apple new products continue, the United States Intel (Intel) introduced Ultrabook laptop to become 3C market, is also the focus of the second half, Intel can sell and become a tool against the iPad, but also Taiwan’s soft board, HDI board In the next year’s performance focus.

Pcb Manufacturing Processing

1,Cut the material by cutting machine like this :


2,Drilling of pcb manufacturing—the first drilling to make all the plated through holes :


3,Planel plating ,make the holes drilled at step2 and the whole panel have copper


4,Place the dry film(photosensitive material) on the board by this kind of machine.

Then Use some software (protel99 , office ,ACD, photoshop ) print the circuit on the negative film ,put this film on the board ,put them in the exposure machine ,the transparency parts of the film will feel the light; then put board into the developing machine, the parts that felt the light of the films will be melted by developing machine .





5, Pattern plating(of course ,before plating , the board will be clean ): make copper cover the reveal parts according to requirement of copper thickness àTin plating : make tin cover the reveal parts to protect the circuit .


7,Etching of pcb processing: first of all ,clean the dry film by NaOH ,and copper uncovered by tin will be cleaned by CuCl2(Cu2++NH4OH+ NH4CL ) and left the circuit covered by tin ,second of all tin that was used to protect the circuit will be cleaned by HNo3 ,after that we will get the formed circuit covered by copper.

8,Middle Inspection step of pcb manufacturing processing: To check if some not good boards ,or some boards can be fixed

9,Solder mask and screen marks : solder mask to protect the circuit and make board looking good ,


screen marks marking the position and orientation of components to make assembly easy.

10,Surface treatment :purpose is to offer the soldering interface ,make pads and some holes with some conduct material ,such as HASL :the tin is the conduct covering the pads ,ENIG: nickel and gold is the conduct covering the pads .

11, Appearance shape: Punching à V-CUT àClean outà Inspection

Pcb is finished


12,TEST:Flying probe or E-test

13,OQC:FQC workers inspect all boards

14,Package and label