train-《Flexible circuit boardintroduce》

Welfare has arrived！Introduction Training Text for Flexible Circuit Boards

 

1FPC Introduction

FPC：Complete English spellingFlexible Printed Circuit, which means flexible printed circuit board in Chinese, abbreviated as' soft board '. It is made by using optical imaging pattern transfer and etching processes on a flexible substrate surface to create conductor circuit patterns. The surface and inner layers of double-sided and multi-layer circuit boards are electrically connected through metalized holes, and the surface of the circuit pattern is protected and insulated with PI and adhesive layers.

 

It is mainly divided into single panel, hollow board, double-sided board, multi-layer board, and soft hard combination board.

PCB：Complete English spellingPrinted Circuit Board, which means rigid printed circuit board in Chinese, abbreviated as hardboard.

 

2、 Development Trends

The soft board industry first emerged in Japan, around the time ofIn 2002. The soft board industry outside of Japan began to sprout in 2003, rapidly expanded in 2005, experienced a decline in 2006, hit rock bottom in mid-2007, and began to recover in 2008.

stayIn 2005, the soft board industry had low entry barriers and high profits, attracting a large number of enterprises to enter.

get intoIn 2006, competition became increasingly fierce, and the phenomenon of oversupply was very serious. Many companies had to lower prices repeatedly in order to survive, and even operated at a loss. At the same time, downstream customers in the soft board industry, such as large EMS manufacturers, have added soft board departments and no longer outsource soft board business, which has made the soft board industry even worse.

2007 was a turbulent year for the soft board industry. Firstly, there has been a significant decline in profits. M-FLEX, a major soft board manufacturer, had a net profit of only $3 million in the 2007 fiscal year, compared to $40.4 million in the 2006 fiscal year, a 93% decrease in net profit. Jiatong Technology, listed in Hong Kong, incurred a loss of $29.8 million in fiscal year 2007, while it made a profit of $12.4 million in fiscal year 2006. Next is the decline in sales revenue. Taiwan's largest soft board manufacturer, Jia Lian Yi, had sales of NT $7.79 billion in 2004, but continued to decline for three consecutive years. In 2007, its sales revenue was NT $6.541 billion.

Once again, the gross profit margin has declined, JialianyiThe gross profit margin was 29% in 2004 and decreased to 12% in 2007. Young Poong, the largest soft board company in South Korea, will divest its soft board business from its listed company to avoid a negative reaction from investors. Even if big factories are like this, small factories will simply go bankrupt.

The large-scale closure of small factories has brought opportunities to the soft board industry, and the soft board industry hasThe recovery began in early 2008. But the soft board industry is facing a new challenge, which is the economic downturn. At the beginning of 2008, the global economy showed a downward trend, with soaring oil prices, subprime mortgage crisis, and skyrocketing food prices. The global economy has entered a downward trend, especially in emerging countries. The decline in demand for soft boards is due to consumer electronics products. When the economy is in a downward trend, the first to be hit is the demand for these non rigid consumer electronic products, including mobile phones, laptops, flat screen TVs, LCD displays, digital cameras, DVs, and other products.

3、 Characteristics of flexible circuit boards

1. Short: Short assembly time

All lines have been configured, eliminating the need for extra wiring connections;

2. Small: smaller in size than PCB (hard board)

It can effectively reduce the size of the product and increase the convenience of carrying it;

3. Lightweight: lighter in weight than PCB (hard board)

Can reduce the weight of the final product;

4. Thin: thinner than PCB (hard board)

It can improve flexibility and strengthen the assembly of three-dimensional space within a limited space.

Advantages of flexible circuit boards

Flexible printed circuit board is a printed circuit made of flexible insulating substrate, which has many advantages that hard printed circuit boards do not have:

1. It can be freely bent, wound, and folded, arranged according to spatial layout requirements, and can move and expand freely in three-dimensional space, thus achieving the integration of component assembly and wire connection;

2. The use of FPC can greatly reduce the volume and weight of electronic products, meeting the needs of electronic product development towards high density, miniaturization, and high reliability. Therefore, FPC has been widely used in fields or products such as aerospace, military, mobile communication, laptops, computer peripherals, PDAs, digital cameras, etc;

3. FPC also has good heat dissipation and solderability, as well as advantages such as easy installation and low overall cost. The soft hard combination design also partially compensates for the slight deficiency of flexible substrates in component load-bearing capacity.

 

Disadvantages of flexible circuit boards

1. High one-time initial cost: Due to the fact that flexible PCBs are designed and manufactured for special applications, the initial cost of circuit design, wiring, and photographic substrates is relatively high. Unless there is a special need to use flexible PCBs, it is usually best not to use them in small quantities;

2. It is difficult to modify and repair flexible PCBs: Once a flexible PCB is made, changes must start from the base map or the developed light drawing program, so it is not easy to make changes. It is covered with a protective film on its surface, which needs to be removed before repair and restored after repair, which is a relatively difficult task;

3. Size limitations: Soft PCBs are usually manufactured using intermittent processes when they are not yet widely available, so they cannot be made very long or wide due to the size limitations of production equipment;

4. Improper operation can easily cause damage: Improper operation by installation personnel can lead to damage to flexible circuits, and soldering and rework require trained personnel to operate.

4Main raw materials for FPC

Its main raw materials are:1. Substrate, 2. Cover film, 3. Reinforcement, 4. Other auxiliary materials.

1. Base material

1.1 Adhesive substrate

The adhesive substrate mainly consists of three parts: copper foil, adhesive, andPI has two categories: single-sided substrate and double-sided substrate. Materials with only one copper foil are single-sided substrates, while materials with two copper foils are double-sided substrates.

1.2 Non adhesive substrate

Non adhesive substrate refers to a substrate without an adhesive layer. Compared to ordinary adhesive substrates, it lacks an intermediate adhesive layer and only has copper foil andPI is composed of two parts and has advantages such as thinner, better dimensional stability, higher heat resistance, higher bending resistance, and better chemical resistance compared to adhesive substrates. It is now widely used.

Copper foil: Currently, commonly used copper foil thicknesses have the following specifications:,1OZ, 1/2OZ, 1/3OZ. We are now introducing thinner copper foils with a thickness of 1/4OZ, but this material is already being used in China to produce ultra-fine (line width and spacing of 0.05mm or less) products. With the increasing demands of customers, this specification of material will be widely used in the future.

 

2. Cover film

It mainly consists of three parts: release paper, adhesive, andPI, only the adhesive and PI parts remain on the product, and the release paper will be torn off during the production process and no longer used (its function is to protect foreign objects on the adhesive).

 

3. Strengthening

byFPC is a specific material used in a specific part of the product to increase support strength and compensate for its softer characteristics.

There are currently several commonly used reinforcement materials:

1) FR4 reinforcement: The main components are glass fiber cloth and epoxy resin adhesive, which are the same as the FR4 material used in PCB;

2) Steel sheet reinforcement: composed of steel, with strong hardness and support strength;

3) PI reinforcement: Similar to the cover film, it consists of three parts: PI and release paper, except that its PI layer is thicker, and can be produced in ratios ranging from 2MIL to 9MIL.

 

4. Other auxiliary materials

1) Pure adhesive: This adhesive film is a thermosetting acrylic adhesive film composed of protective paper/release film and a layer of adhesive. It is mainly used for laminated boards, soft hard bonding boards, and FR-4/steel reinforcement boards, playing a bonding role.

2) Electromagnetic protective film: pasted on the board surface to provide shielding effect.

3) Pure copper foil: composed only of copper foil, mainly used in the production of hollow boards.

5Types of FPC

There are six types of FPC distinctions:

A. Single panel: Only one side has wiring.

B. Double sided board: There are lines on both sides.

C. Hollow board: also known as window board (finger face opening window).

D. Layered board: Two sided circuit (separated).

E. Multilayer board: Two or more layers of circuits.

F. Soft hard combination board: a product that combines soft and hard boards.

VIFPC process flow

 

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