4. Other auxiliary materials
1) pure adhesive: this adhesive film is a kind of thermosetting acrylic ester adhesive film, which is composed of protective paper/release film and a layer of adhesive, mainly used for lamination board, soft and hard bonding board, and fr-4 / steel sheet reinforcing board to play an adhesive role.
2) electromagnetic protection film: paste on the board to play a shielding role.
3) pure copper foil: composed only of copper foil, mainly used for hollow plate production.
5. Types of FPC
There are six types of FPC:
A. Single panel: only one side has the circuit.
B. Double panel: there are lines on both sides.
C. Hollow plate: also known as window plate (window opening on finger side).
D. Layering board: two sides of circuit (separate).
E. Multi-layer board: more than two layers of lines.
F. Hard and soft board: products combining soft board and hard board.
I. introduction to FPC
FPC: isn’t it common to say that Flexible Printed Circuit means Flexible and Printed Circuit board? It is a conductor circuit pattern made by light imaging pattern transfer and etching process method on a flexible substrate surface. The surface and inner layer of double-sided and multilayer circuit board are electrically connected through metallized holes. The circuit graph surface is protected and insulated by PI and rubber layer.
It is mainly divided into single panel, hollow board, double panel, multilayer board and hard and soft combination board.
Printed Circuit Board: Printed Circuit Board, Printed Circuit Board, Printed Circuit Board
Second, the development trend
Soft board industry first emerged in Japan, the time is about 2002. The soft board industry outside Japan began to sprout in 2003, expanded rapidly in 2005, and declined in 2006. In mid-2007, the soft board industry hit the bottom, and began to recover in 2008.
In 2005, the soft board industry low threshold, high profit, attracted a large number of enterprises into.
In 2006, the competition became increasingly fierce, and the phenomenon of oversupply was very serious. In order to survive, many enterprises had to lower their prices again and again, or even operate at a loss. At the same time, the softboard industry’s downstream customers, such as large EMS manufacturers, add softboard departments, no longer outsourcing softboard business, resulting in the softboard industry.
2007 was a year of ups and downs for the soft board industry. The first is the sharp decline in profits. In fiscal year 2007, the net profit of m-flex was only 3 million dollars, while in fiscal year 2006, the net profit reached 40.4 million dollars, with a 93% decline. Giti, which is listed in Hong Kong, lost $29.8m in fiscal 2007, compared with a profit of $12.4m in fiscal 2006. The second is the decline in sales. Jialanyi, Taiwan’s largest flexible board manufacturer, had sales of nt $7.79 billion in 2004 and then declined for three consecutive years, with sales of nt $6.541 billion in 2007.
Once again, the gross profit margin fell. In 2004, the gross profit margin was 29%, and in 2007, the gross profit margin fell to 12%. Young Poong, South Korea’s biggest soft-board firm, is spinning off its soft-board business from listed companies to avoid investors looking too glum. Even if the big factory is like this, the small factory will go out of business directly.
A large number of small factory closures to the soft board industry brought opportunities, soft board industry since the beginning of 2008 began to recover. But the soft board industry is facing a new problem, which is the economic downturn. At the beginning of 2008, the global economy showed a downward trend, with soaring oil prices, the subprime mortgage crisis and soaring food prices. The global economy is on a downward trajectory, especially in emerging economies. The decline in demand for soft panels was driven by consumer electronics. When the economy is in a downturn, the first to suffer is the demand for these non-rigid consumer electronics: including mobile phones, laptops, flat-screen televisions, liquid crystal displays, digital cameras, DV and other products.
The characteristics of flexible circuit board
A. short: short assembly time
All lines are configured, eliminating redundant wiring.
2. B. smaller than PCB (hard board)
Can effectively reduce the volume of products, increase the convenience of carrying;
3. Light: lighter in weight than PCB
Can reduce the weight of the final product;
4. Thinner: thinner than PCB (hard board)
It can improve the softness and strengthen the assembly in the 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 rigid printed circuit board does not have:
1. It can bend, wind and fold freely, and can be arranged in accordance with the requirements of spatial layout, and move and expand in three-dimensional space arbitrarily, so as to achieve the integration of components assembly and wire connection;
2. FPC can greatly reduce the size and weight of electronic products, which is suitable for the development of electronic products in the direction of high density, miniaturization and high reliability. Therefore, FPC has been widely used in aerospace, military, mobile communications, laptop computers, computer peripherals, PDA, digital camera and other fields or products.
3. FPC also has the advantages of good heat dissipation and weldability, easy assembly and low comprehensive cost. The soft and hard combination design also makes up for the slight deficiency of flexible substrate in the bearing capacity of components to some extent.
Disadvantages of flexible circuit boards
1. High one-time initial cost: since flexible PCB is designed and manufactured for special applications, the initial cost of circuit design, wiring and photographic substrate is relatively high. Unless there is a special need to apply soft PCB, usually a small number of applications, it is best not to use;
2. It is difficult to change and repair the soft PCB: once the flexible PCB is made, the change must start from the base drawing or the light drawing program, so it is not easy to change. Its surface is covered with a protective film, which should be removed before repair and restored after repair, which is a difficult job.
3. Size limitation: soft PCB is usually manufactured by batch process when it is not widely used. Therefore, it is limited by the size of production equipment and cannot be made very long or wide.
4. Improper operation is easy to damage: improper operation of assembly personnel is easy to cause damage of soft circuit, and its tin welding and rework need trained personnel to operate.
Iv. Main raw materials of FPC
Its main raw materials right: 1, substrate, 2, cover film, 3, reinforcing, 4, other auxiliary materials.
1, base material
1.1 adhesive substrate
There are three main components of adhesive substrate: copper foil, adhesive, and PI. There are two categories of single-sided substrate and double-sided substrate. The material with only one copper foil is single-sided substrate, and the material with two copper foils is double-sided substrate.
1.2 non-adhesive substrate
Without glue of base material is a no sub base material, it is compared with the ordinary rubber base material, the less the middle of the sub, only copper foil and PI in two parts, is better than have a rubber base material with thinner, the size stability, higher heat resistance, higher resistance to bending, better chemical resistance and other advantages, is widely used now.
Copper foil: at present, the commonly used thickness of copper foil has the following specifications: 1OZ, 1/2oz, 1/3oz. Now, the thinner copper foil with the thickness of 1/4 oz is introduced. However, at present, this material is already used in China to make ultra-fine lines (line width and line spacing of 0.05mm and below). With the increasing requirements of customers, materials of this specification will be widely used in the future.
2. Covering film
There are mainly three parts: release paper, glue, and PI, which are finally retained on the product with only glue, glue and PI. Release paper will be removed in the production process and will not be used again (its function is to protect foreign matters on glue).
For FPC specific use of materials, in a specific part of the product to increase the strength of support, make up for FPC’s “soft” characteristics.
Currently, commonly used reinforcing materials are as follows:
1) FR4 reinforcement: the main components are glass fiber cloth and epoxy resin adhesive, the same as FR4 used in PCB;
2) steel sheet reinforcement: it is composed of steel with strong hardness and supporting strength;
3) PI reinforcement: the same as the covering film, it is composed of PI and rubber release paper, but its PI layer is thicker, which can be produced from 2MIL to 9MIL.