When the length of the single-sided double-contact FPC electrode is greater than 3.0mm and the width is less than 0.3mm, it is easy to cause deformation, distortion and fracture of the electrode in the process (etching, removing film, surface cleaning, and sticking protective film), which seriously affects the yield of the product. If our company took such an order before, according to the normal process production, the yield is very low, only about 50%, even the goods can not be delivered. After the process improvement, the yield increased to 85~93%. Here is how to improve the process:
1. Starting point of process improvement:
We assume that part B is the part that needs to be hollowed out in the process (pressing the top protective film after etching). When this part is hollowed out, there is no strengthening part to support the hollowed out electrode, which is easy to cause distortion, deformation and fracture of the electrode under the action of external forces (such as the spray pressure of the horizontal machine, rewinding and transportation). So the key to improving the process is to give the fragile electrode a support.
2. Selection of supports:
Since the support is used from before etching to the upper protective film, it is especially necessary to perform hot pressing. Therefore, we must choose substances that can withstand high temperatures. Here you can choose high temperature tape (such as KAPTON tape KA00), the tape requires the glue will not transfer, can withstand the high temperature of the press (fast press).
3. Process description:
3.1 The line is done with wet film, screen printing B side first, after baking, screen printing A side, and then baking. Then exposure, development, the point of attention in this step is that the B-side does not need to be exposed, if exposure will cause subsequent film removal difficulties;
3.2 After development, tape side B (paste on the surface of the wet film), as shown in Figure 2. Here, it should be noted that the high temperature tape should be pasted flat, and when there is a reinforcement alignment mark, the tape should try not to exceed the mark line, because there will be a little trace in the high temperature tape position after pressing, if there is reinforcement, it can just cover the indentation;
3.3 Etching, development and surface cleaning shall be carried out according to normal steps;
3.4 Pressing of the upper protective film (pressing with a fast press). At this time, it is necessary to optimize the pressing parameters, and the optimization principle is to use the least time, the least pressure and the lower temperature. Because of high temperature, long time and large pressure, it is easy to cause the transfer of high temperature glue and the difficulty of removing the wet film covered by high temperature glue.
3.5 Tear off the high-temperature tape, remove the film (careful operation), and grind the plate to remove the ash copper at the electrode;
3.6 Bake and solidify the protective film;
3.7 The following operations are as usual.
This method is a soil method, the process is also slightly troublesome, and additional high-temperature tape auxiliary materials are required. However, I think it is still very suitable for the manufacture of single-sided double-contact FPC with electrode length greater than 3.0mm and width less than 0.3mm, which is sure to improve the yield.
You can try if you are interested, and weigh the pros and cons yourself.
5 Influence of IPD technology on PCB technology development
With the progress of technology, PCB printed circuit boards are developing in the direction of higher precision and higher density, and gradually and highly integrated in the field of IC packaging, passive component integration is in line with the development trend of today's electronic systems, IPD technology has become an important way to achieve system-level packaging (SiP).
IPD integrated passive component technology has the advantages of high wiring density, small volume and light weight. High integration, can be embedded resistance, inductance, capacitance and other passive devices and active chips; Good high-frequency characteristics, can be used in microwave and millimeter wave fields and other advantages. The application of thin film IPD integrated passive component technology to PCB processing, to save packaging area, improve signal transmission performance, reduce costs, improve reliability and other purposes, through the integration advantages of IPD technology, bridge the gap between packaging technology and PCB technology, can effectively reduce the volume and weight of electronic machine and system. It has broad market prospects.
PCB processing for IPD integrated passive components can be used as a substrate with high thermal conductivity of metal, diamond, ceramic or aluminum-carbonized silicon composite materials, etc., to manufacture high-density and high-power multi-layer circuit board, and should strengthen the process improvement of IPD passive integrated PCB substrate. Improved material properties and low cost, as well as accelerated applications in microwave communications, high density integration and high power.
Thin-film IPD integrated passive component technology can integrate a variety of electronic functions, has the advantages of miniaturization and improved system performance, and can replace the large volume of discrete passive components. At the same time, PCB processing can introduce IPD technology, through the integrated advantages of IPD technology, can bridge the widening gap between packaging technology and PCB technology.
The rapid development of thin film IPD integrated passive component technology, so that passive integration technology has entered the practical and industrialization stage, a new generation of passive components and related integration technology, will be widely used in aerospace, military, medical, industrial control and communications and other fields of the electronic industry, so the development of IPD technology, Whether it is for the development of the enterprise itself or to enhance the competitiveness of the domestic industry is of great significance.