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.

 mpcb-22ss-web missionstatement  

 

mcpcb-1ss-web

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.

The structure, technique and design of FPC (1)

As more and more clamshell phones come into market, the FPCs are more and more used.

 According to the combination ways of the base material and the copper, the FPCs can be divided into two kinds: adhesive FPC and adhesiveless FPC.

 The price of adhesiveless FPC is much higher than the adhesive FPC. However it is superior to FPC in the aspects of flexibility, boning force of copper and the base material, and the flatness of soldering pad. Therefore generally it only is used in the occasion of high demand, such as COF (chip on flex, to mount exposed chips on FPC has high requirement of the soldering pad flatness).

 Due to adhesiveless FPC’s high price, at present most of the FPCs applied at the market are adhesive.

 Because the FPC is mainly used at the occasion of bending, if the design or technique is not proper, defaults such as micro-crack, snap of the welding point will be easy to arise. I will introduce the structure of FPC and its special requirements on design and technique.

FPC for LCD Module

FPC for LCD module also named  LCD Module FPC. This kind of FPC is flex printed circuit used in connected with LCD, in most case. So its someone named it as “LCD module FPC” or “FPC for LCD Module”.

LCD Mould FPC top view

LCD Mould FPC top view

One end of FPC will be inserted into the connection area of LCD and the others will be connected with other input or output machines. The major function is to transfer data smoothly and safetly.

LCD Mould FPC bottom view

LCD Mould FPC bottom view

As quantiyt of LCD is related big, so the quantyt for this kind of FPC will also have a certain quantity. So people should be very careful in designing and manufacturing, because normally the L/S and L/W is small, about 3~4 mil. Without suitable manufacturing artwork and technology, the yield will be very low.

We have much experience on making LCD flex circuits, knowing what’s the keystone, what kind of problems maybe happened owing to its own charactericstic, how to avoid it and how to make FPC in great condition.

Please contact Best Technology now for more informaiton about  FPC for LCD moduleLCD Module FPC.

LED Flexible Circuits (Article2)

Last time, we have dicussed the feature of LED flex circuit, and this time, we will mention the way to make that Flexible circuit

1) The whole Flex circuit is the repeated of several section of FPC.

led flex circuit solder togetherSo we can populate LEDs, as well as ICs, etc, on FPC. And then solder each sections together, strip-by-strip, to make a long flex circuit boards. 

led-flex-circuit-solder-together

led-flex-circuit-solder-together on a roll

After several strip of FPC is connected by soldering, or using connector, we will do testing and then packing them in a roll, normally 3 meter, or 5 meter. It should be packing in vacuum packing. 

  2) Just make the enough length single FPC one time, without the soldering connecting.

 This is used in some special end-products which obvious soldering is prohibitted and more strength is needed. Of course, this kind of FPC is more difficult to make, becuase of manufacuturing artwork & equipment limited.  

Long Led Flex Circuits

Long Led Flex Circuits

Right now, we can make, maximum 3 meter (118 inch) one. Of course, the cost is more expensive than method 1. Popular length is 0.8meter(31.5inch), 1.0 meter (39.37inch), 1.2 meter (47.25 inch), or 1.8 meter (70.87 inch).
 
More long, more expensive, as the manufacturing will become more and more complex, and need high technology to control whole process, from developing, etching, coverlay lamination, outling punching.
 

 

Cuttable flex circuit

Cuttable flex circuit

Sometimes, poeple like to cut the customized lenght at his side according to different requirement. 

 

 so during design process, engineer will consider cuttable length such as 30mm, 50mm. This will give customer great convenience. 

 How’s your opinion about them? Do you have any questions or problem when used this kind of FPC? Or want to try ours?

Please don’t hesitate to contact BEST FPC CO., LTD. for more information about Flexible Circuits with LED (LED Flexible circuit boards). We are always to be your best parter of FPC in Asia.
 

LED Flexible Circuits

Recently, more and more people pay attention on the Flexible circuit with LED (or said LED Flexible circuit). Along with the FPC industry growing, as well as the LED application spread out, there’s continue request of precision lighting & luminescnce in some special circumstance.

LED FPC

LED FPC

In fact, this Flexible circuit with LED is a special single sided fpc or two layers FPC, with adhesive tape at the bottom side, easy peel off and installation. The outstanding characteristic is its length. Theoretically, the length of this Flexible circuit can be made according to clients’ request.

The popular maximum length currently used, however, is about 8-10 meter (2.5-3.0 ft), because of power and thermolysis limited.  (Please browse our site for more: http://www.bestfpc.com/products/single-sided-fpc.htm, http://www.bestfpc.com/products/double-sided-fpc.htm).

Here we’d like to talk about some features of Flexible Circuits with LED & LED Flexible Circuits

1) Separable SMD/SMT LED strip on Flexible circuit boards can be bended to the tour of any products with self adhesive tape back, easy installation! They are mounted on self-adhesive tape and can be conveniently field-cut. For adhesive tape, normally we use 3M 467/946/966, or as per request.

2) As long as the clients request (strip-to-strip soldered connecting). You can also choose our extreme long FPC which is 9.8 feet (3m) without soldering.

3) This flex circuit modules, after LED SMT/SMD were done, are ideal for edge lighting transparent and diffuse material. They provide an optimal solution for precise backlighting of complex contours. They can also be used of lifesaving/rescue sign lights and commercial signs and for making contours like escape routes, borders and stairs.

4) Customer design LED location, quantity, color (red, green, blue, true green, white (phosphor on blue), yellow, etc), according to the request of luminous intensity & color.

5) Flexible circuit boards (FPC) surface in white finish, with classic looking, or as per request

6). With IC constant current circuits, guarantee stable working current and even light output for the whole reel of lights.

In next article, we will discuss the way/method to make this type of LED Flexible circuit)

Related article: Led Flexible Circuit (Article 2)

Definition of FPC

When we talk about the FPC in our industry, most of us know it stands for Flexible Printed Circuit, the update products of PCB. Also for the Flexible Circuits, the most broadly accepted defi nition is the one that is found in the industry standard IPC-T-50 Terms and Defi nitions for Printed Boards. In that document, flexible circuits are defi ned as “A patterned arrangement of printed wiring utilizing fl exible base material with or without fl exible coverlayers.” 

Each person in circuit industry will know its definition (meaning), but do you FPC also stands for other meanings?

 You can search FPC via Google, when you will find the top sites whom appear in the first page of searching results have little relation to Flexible Printed Circuit. For more, click here for FPC searching result.

Is it funny? In fact, it’s a popular phenomenon in our daily life. Things maybeÂare different from what we thought. We have to dig it. The follows are some definition of so called ‘FPC’ in different language(from wiki):

German:

  • Free Pascal ist ein Open Source-Projekt, das sich zum Ziel gesetzt hat, einen freien, 100%ig kompatiblen Turbo Pascal-Klon zu programmieren. Das Projekt ist weit fortgeschritten.Es steht auch die Option der Nutzung unter der LGPL zur Verfügung, so dass auch ein kommerziellerEinsatz möglich ist, siehe hierzu die Lizenzbedingungen.
    de.wikipedia.org/wiki/Fpc

French:

Formation Professionnelle Continue www.knowup.com/pages/ressources/lexique.cfm/ 

English:

Florida Parole Commission is responsible for making decisions on the granting and revoking of parole. FPC also reports to the Board of Executive Clemency the circumstances, the criminal records, and the social, physical, mental, and psychiatric conditions and histories of persons under consideration by the board for pardon, commutation of sentence, or remission of fine, penalty, or forfeiture. … www.fcc.state.fl.us/fcc/reports/final98/98gloss.html

  • Predecessor of FERC
    www.saludahydrorelicense.com/glossary.htm
  • Front Page Challenge (aired 1957 – 1995) was a Canadian current events-cum-history program disguised as a game show, in which notable journalists attempted to guess what past news story the hidden guest was linked with. Upon conclusion of he challenge, the journalists served as a panel of interviewers as they conversed with the guest about the story in question.
    en.wikipedia.org/wiki/FPC

Dutch: 

Portuguese:

Federa o Portuguesa de Campismo. Organismo reconhecido pelo estado Portugus, com a tutela, atravs da sua actual Escola Nacional de Montanhismo, de coordenar a pr¡tica montanhismo e escalada em Portugal.
luis-avelar.planetaclix.pt/dicionario/dicio_f.ht

At the end of this artile, remind the reader again, if you want know the real meaning of FPC in the circuit industry, please visit our homepage where you will find out what a real Flexible Printed Circuit is!