CN204272492U - A single-sided flexible circuit board - Google Patents

Abstract

The utility model discloses a single-sided flexible circuit board. An ink layer is provided on one side of the copper foil that has been punched out, and a PET film is provided on the other side of the copper foil. A thermosetting adhesive layer is provided between the PET film and the copper foil. , the PET film is bonded to the copper foil through a thermosetting adhesive layer. The utility model has a structure of 4 layers, and through the cooperation of the PET film and the thermosetting adhesive layer, the defect that the PET film is easy to shrink and warp when used alone is solved.

Description

A single-sided flexible circuit board

technical field

The utility model relates to the technical field of circuit boards, in particular to a single-sided flexible circuit board.

Background technique

Flexible Printed Circuit Board (Flexible Printed Circuit Board) referred to as "soft board", commonly known as FPC in the industry, is a printed circuit board made of flexible insulating substrates (mainly polyimide or polyester film), with many rigid printing Advantages that circuit boards do not have. For example, it can be bent, rolled, and folded freely. The use of FPC can greatly reduce the volume 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 cameras and other fields or products.

Flexible circuit boards are divided into single-layer boards, double-layer boards, multi-layer boards, and double-sided boards according to the number of layers of conductive copper foil. The existing flexible circuit board is provided with PI films on the front and back sides of the metal foil respectively, and the PI film and the metal foil are bonded together by epoxy glue, and then a layer of ink is coated on the PI film, that is, there are 7 layers. structure, the cost is relatively high. And due to the properties of PI film and epoxy glue, the prepared traditional flexible LED substrate can only be stored at low temperature and has a short lifespan. In addition, most flexible circuit boards use etching technology, and more or less lines will have uneven edges.

Application No. 201010232537.2 of the Chinese patent "Method for Making Single-Sided Circuit Board Using Juxtaposed Wires" discloses a method of manufacturing single-sided circuit boards using juxtaposed flat wires, directly using the cover film with the pad window and After the juxtaposed flat wires are thermocompressed and bonded, the position where the flat wires need to be disconnected is cut off, and then pressed together on the adhesive circuit board substrate, and the bridge connection is connected by printing conductive ink or soldering conductors. It can be seen that the patent heat-presses the covering film after a plurality of flat wires are arranged in parallel, and two adjacent parallel lines can only be connected by connecting bridges, so it cannot be used for complex circuit designs, especially when there are many turning connections. It is difficult to ensure the long-term stability of the solder joints, and it is easy to affect the use due to false soldering. In addition, the patented process is complicated, and the flat wires need to be disconnected after hot pressing. Position, then press-fit to the circuit board base material, and then solder the connection bridge, once the process is complicated, the production capacity will be low, and this method can only be applied to the case of simple circuit, not suitable for complex circuit design, and cannot be widely used Promote apps.

The Chinese patent "circuit board with die-cut circuit" with the application number of 201020559880.3 discloses a circuit board with die-cut circuit. A circuit board cuts off part of the unnecessary metal of the circuit by die-cutting, but retains the metal connection The supporting position, and then use a thermosetting adhesive film, or use a cover film with a window, or use a transfer adhesive film, or use an insulating substrate with adhesive to stick it on the side that has been punched and removed part of the metal, Or use the window-opened cover film and the insulating base material with glue to bond at the same time to the two sides that have been punched and removed part of the metal, and use a mold to cut off the remaining metal connection support to make it with a die-cut circuit. circuit board. This patent uses a die-cutting method for multiple punching of the circuit board. The structure is provided with a connection support position, and finally the connection support position is cut off. The overall structure is that both the thermosetting adhesive film and the insulating insulation substrate have punching cuts. , and the whole preparation process is multiple punching, there is a defect of misalignment.

To sum up, due to the different preparation methods used, the structures of the prepared flexible circuit boards are not the same. For example, the etched flexible circuit board circuit can be simple or complex, but the edges of the circuit will inevitably have irregularities, such as the application number The flat wire hot-pressing cover film used in the Chinese patent "Method of Making Single-sided Circuit Board Using Juxtaposed Wires" in 201010232537.2, from the structural point of view, there are cuts on the front and back of the circuit board, and the middle layer is a strip of flat wires. There are some soldered connecting bridges between the flat wires, which are not beautiful except that the circuit is simple; such as the die-cutting technology adopted in the Chinese patent "circuit board with die-cut circuit" with application number 201020559880.3, the same circuit board circuit is simple , There are cuts on the front and back sides, and the copper foil layers are spliced in parallel one by one. The curved lines can only be bridged by welding through two parallel straight lines, which is not beautiful. In addition, the alignment is not accurate due to multiple punching.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a single-sided flexible circuit board with simple structure, neat circuit edges, neat alignment and long service life.

The above-mentioned purpose of the utility model is achieved through the following technical solutions:

A single-sided flexible circuit board, one side of the punched copper foil is provided with an ink layer, the other side of the copper foil is provided with a PET film, a thermosetting adhesive layer is provided between the PET film and the copper foil, and the PET film Adhesive to copper foil through thermosetting adhesive layer. The structure of the utility model is 4 layers. In order to overcome the defect that the PET film is easy to shrink and warp at high temperature, the utility model is provided with a thermosetting adhesive layer on the PET film on the one hand. Adhere to the PET film to reduce the tendency of the PET film to shrink when heated, thereby reducing the possibility of the PET film shrinking and warping. The stretching ratio reduces the ratio of heat shrinkage of the high temperature resistant PET film in the later stage. In addition, the circuit on the copper foil of the utility model is to use a cutting knife to cut the copper foil. The specific process is to set the cutting edge of the cutting knife into a shape corresponding to the circuit, and then punch it. Only one punching is required, so the The bits are neat and the line edges are neat.

The thermosetting adhesive layer is a polyester adhesive layer. The thickness of the thermosetting adhesive layer is 20-30 μm. Traditionally, PI film and epoxy glue are used. Due to the properties of PI film and epoxy glue, the traditional flexible circuit board prepared can only be stored at low temperature and has a short life. This problem can be overcome by using PET film and polyester adhesive layer instead.

The PET film is also provided with punching cuts corresponding to the lines on the copper foil. The thickness of the ink layer is 10-20 μm. The ink layer has the function of solder resisting, and also has the property of surface heat dissipation.

Compared with the prior art, the beneficial effects of the utility model are as follows:

(1) The structure of the utility model is 4 layers, through the cooperation of the PET film and the thermosetting adhesive layer, it solves the defect that the PET film is easy to shrink and warp when used alone;

(2) PET film and polyester adhesive layer are used instead of PI film and epoxy adhesive layer, which can be stored at room temperature and have a long service life.

Description of drawings

Fig. 1 is the structural representation of the present utility model; Wherein, 1, ink layer; 2, copper foil; 3, thermosetting adhesive layer; 4, PET film.

Detailed ways

The utility model will be further elaborated below in conjunction with the accompanying drawings and specific embodiments, but the embodiments do not limit the utility model in any form.

Example 1

A single-sided flexible circuit board, an ink layer 1 is provided on one side of a copper foil 2 that has been punched out, and a PET film 4 is provided on the other side of the copper foil 2, and a thermosetting film 4 is provided between the PET film 4 and the copper foil 2. The adhesive layer 3, the PET film 4 is bonded to the copper foil 2 through the thermosetting adhesive layer 3. The PET film 4 is also provided with punching cuts corresponding to the lines on the copper foil 2 .

Further, the thermosetting adhesive layer 3 is a polyester adhesive layer. The thickness of the ink layer 1 is 15 μm. The thickness of the thermosetting adhesive layer 3 is 25 μm.

Claims (5)

1. a single-sided flexible circuit board, is characterized in that, the Copper Foil one side of die-cut good circuit is provided with ink layer, and Copper Foil another side is provided with PET film, is provided with thermosetting glue-line between described PET film and Copper Foil, and described PET film is bonded by thermosetting glue-line and Copper Foil.

2. single-sided flexible circuit board according to claim 1, is characterized in that, described thermosetting glue-line is polyester glue-line.

3. single-sided flexible circuit board according to claim 1, is characterized in that, described PET film is also provided with the die-cut mouth corresponding with the circuit on Copper Foil.

4. single-sided flexible circuit board according to claim 1, is characterized in that, described ink film thickness is 10 ~ 20 μm.

5. single-sided flexible circuit board according to claim 1, is characterized in that, described hot-setting adhesive layer thickness is 20 ~ 30 μm.