Polyester film or polyimide as the basis for the production of Polyester PCBs is a flexible excellent, highly reliable printed circuit boards, also known as the industry's flexible circuit boards, flexible circuit boards, because of its thin thickness, lightweight, but also free to bend and fold, so that the electronics industry highly favors it.
Blind Hole Plating for Flexible Circuit Boards
With the rapid development of the domestic new energy automobile industry, making the design of the automotive circuit board density, and precision requirements increasingly high, continuing use of the traditional manual testing FPC method, it has been difficult to meet the current new energy automobile production needs, but also to make FPC defects automated inspection system has become a new energy automotive industry, an inevitable trend in the future development of the industry. The circuit design is embedded in a bendable and undamaged thin plastic sheet, so that it is in a limited narrow space, can maximize the stacked embedded electronic precision components, and the formation of flexible circuits can be bent, this type of electronic components circuit folding weight is relatively light, can be bent at will, but also has the advantages of easy installation, good heat dissipation, small size, etc., can be composed of the main conductor, insulating film, bonding agent, etc., the flexible circuit board together. Structure.
Can take the form of multiple circuit layers stacked on top of each other to better meet the new energy vehicles on the flexible circuit board complex lines of high-density interconnection needs, microvia metallization as the current stage of multi-circuit layer electrical interconnection technology as the main application of the program, according to the actual interconnection of different models of circuits on the circuit needs, the first in the circuit layers between the preparation of the appropriate amount of blind holes, buried holes, holes, and then plating method of the implementation of the micro-porous copper-plating technology to allow the deposition of the copper layer in the holes, so that the copper layer is deposited in the holes. The thickness of the copper layer deposited in the holes can meet the interconnectivity between the electrical. Because the flexible circuit boards used in new energy vehicles need to have the requirements of bending and deformation without damaging the circuit performance, its structure is fragile, therefore, in the use of blind hole plating technology, we must ensure that the copper layer deposited on the surface of the circuit board is ultra-thin thickness.
Types of additives used in blind hole plating technology for flexible circuit boards
The use of chloride ions, sulfuric acid, copper sulfate plating solution can be made in the electric field force, the plating solution of copper ions to move to the negatively charged cathode, and in the cathode around the surface of the copper singlet reduction of electrons, and ultimately the formation of cathodic electrodeposition. The whole process relies on additives to promote or hinder the effect of copper deposition, by changing the rate of nucleation of copper atoms, to enhance the quality of the copper layer of deposited copper. At present, the more common copper plating additives on the market are accelerators, chloride ions, leveling agents, and inhibitor four.
Accelerators are mostly sulfur-containing organic matter and can accelerate the cathodic deposition rate of copper ions, but also allow the deposited copper surface to be more bright, and detailed, also known as a brightener. The relevant research shows that the accelerator only in the electroplating solution under the condition of chloride ions, to play its effective role in accelerating the deposition of copper ions, on the contrary, there are no chloride ions in the electroplating solution, then, adsorbed in the cathode surface around the accelerator has become an obstacle to prevent the flow of copper ions to the cathode surface of the obstruction layer, to play a role in inhibiting the reverse role of the copper ions deposited.
Chloride ions for inorganic additives, not only can prevent the motor passivation reflection, but also promote the effective dissolution and deposition of the electrode, so that adsorbed in the surface of the copper layer of chloride ions built into the chlorine bridge, to accelerate the rapid transfer of electrons, but also with the plating solution exists between the formation of synergistic effects between other additives to strengthen the chloride ions on the inhibitor to inhibit the strength of the circuit of the over-potential, thus increasing the density of the nucleation of the blind hole electroplating This will ultimately achieve the goal of improving the quality of copper plating.
Leveling agent with nitrogen-containing heterocyclic compounds or positively charged quaternary ammonium compounds, such as Kenna green, diazine black, blind hole plating, the leveling agent will first adsorb copper ions around the cathode surface in the area of the lower point, or the current density of the larger area of the copper ions, to achieve the effect of slowing down the rate of copper ion deposition in the region [2]. After many previous tests, it is known that the potential of the protruding tip part of the cathode surface is the most negative state, so the adsorption concentration of the leveling agent in this area is the highest, to play a full role in inhibiting the deposition rate of copper ions in this area, so that the cathode copper deposition rate becomes more uniform, and then improve the leveling of the coating of the blind hole plating. It can be seen that chloride ions still play a synergistic leveling function in the leveling agent plating process, playing the role of bridging the leveling agent and copper deposition rate.
Inhibitors are mostly fatty alcohol polyoxyethylene ether, polyethylene glycol, and other polyether-based organic substances, and chloride ions have a synergistic effect with the formation of a layer of high-density adsorption layer on the cathode surface, play a role in hindering the adsorption of copper ions to the cathode, the role of diffusion, thus enhancing the deposition of copper ions over-potential, to play a role in inhibiting the deposition rate of copper ions, to enhance the tightness of the interlayer copper plating.
Flexible circuit board blind hole plating mechanism of action
In Polyester PCB blind hole plating technology without the use of additives, it is difficult to make the plating solution on the blind holes to achieve the role of non-void super-filling, must be rationed additives in order to effectively play out the synergistic deposition of the plating solution, through the copper ions in the region of the deposition rate is effectively regulated in a way that improves the super-filling of blind holes in the plating process technology. Because the blind hole plating process is more complex, it is difficult to use a single chemical, or physical behavior to explain, the naked eye is not directly discernible, which allows people to blind hole plating technology for flexible circuit boards using additives in the role of the mechanism is more fuzzy, a serious impediment to the development of additives in the application of flexible bandwidth to work in the speed of the development of blind hole plating technology.
At present, the more commonly used chemical test method to indirectly study the behavior of additives, has also become a common method to analyze its mechanism of action. After years of joint research by many scholars, the role of blind hole plating on flexible circuit boards gradually revealed the mechanism. First of all, through the inhibitor will be far from the cathode of the plating solution transfer to the blind hole mouth and hole, this process is affected by the natural diffusion, so that the inhibitor flow rate to the bottom of the hole is relatively slow, not to supplement the role of blind holes, resulting in the bottom of the hole inhibitor adsorption concentration is much lower than the concentration of the mouth, to further promote the copper ions from the bottom up for the deposition of holes, and ultimately to realize the effect of plating filling of the blind holes without cavities. Secondly, using the curvature-enhanced accelerator model for plating tests, it was found that when the inner diameter of the blind holes in the plating process, the copper ions on the surface of its cathode in the deposition of copper ions, but also the corresponding contraction behavior, in order to increase the curvature accelerator on the adsorption of copper ions adsorption rate, but in terms of the leveling agent, inhibitor, this model of the electroplating process, there is an obvious defect. Finally, using the convection-dependent adsorption model for plating tests, it was found that the leveling agent and chloride ions in the process of transfer will be controlled by convection, and then in the area of higher adsorption concentration of the leveling agent, and chloride ions and inhibitors can form a relatively dense barrier layer between the inhibitor, to achieve the role of inhibiting the intensity of copper ion deposition.
In addition, the overall quality and effectiveness of the flexible circuit board blind hole plating process, but also with the following factors:
(1) FPC plating process for thin-thickness plating, its stainless steel stacking rate is directly associated with the strength of the power plant and the electric field strength will be transformed with the circuit board roadmap type of motor position, style relationship, according to experience can be known, sizing line spacing the thinner, the circuit board terminals at the terminal position of the terminals will be the sharper, and the closer the distance from the electric level, the electric field strength here will be the more the position The plating coating will be thicker.
(2) A flexible circuit board in the completion of the map cover processing process is exposed in the external surface layer of the copper wire if the printing oil or adhesive is not only the surrounding environment, but also the new energy vehicles in the late production and use, due to the rise in ambient temperature and color loss, air oxidation and other issues, so the new energy vehicles in the manufacture of flexible circuit boards in the blind plating process, to ensure that the close coating of the Excellent adhesion, must be removed from the circuit board electrical conductors on the surface layer of the reflective layer, to complete the surface cleaning process.
(3) flexible circuit board blind hole plating process processing, there may be a variety of solutions in the depression hoarding or saturation problems, the parts here will occur color loss reaction, in order to effectively avoid the occurrence of such events, can be carried out in the plating process sufficient drying to solve the problem, at the same time do not open the bleeder to the fullest, the process link according to high-temperature heat aging test, to detect whether the bleeder is sufficient problem. This process is based on the high-temperature thermal aging test to detect whether the drift is sufficient.
(4) wire lap (welding) electroplating process than the melting electrode welding plating of lead and tin process is more stringent operating specifications, in the operation of the technicians need to be strictly by the position specification of the relative release of pressure processing to ensure that the process of the processing effect.
Group Profile
ZHUHE Group is a comprehensive service provider of electronic technology and electronic products for more than 10 years. Starting from a small company, we have continued to expand the field of electronic applications and provide customers with advanced intelligent control solutions, and have grown to have 11 subsidiaries of our own. We can provide professional OEM/ODM service to our customers. The company has standardized management and insists on providing customers with high-quality products and services.
ZHUHE Group R & D and manufacturing of the rapid development of digitalization is the development of a major trend, ZHUHE Group was named "national speciality, speciality, and new" enterprises, ZHUHE Group has been focusing on the following four aspects of the enterprise's long-term competitiveness:
- globalization resource control (including human resources, and upstream supply resources);
- technological product and service research and development (through technological means to carry out product research and development, to enhance competitive advantage);
- Digital precision manufacturing power (through intelligent manufacturing system to achieve high efficiency, high reliability of product production);
- Internationalization market development power (Jieh has been facing the global market layout, such as Japan Jieh, sales of all products within the group).
The company to R & D as the core driving force, through its own strong R & D strength, relying on stable, high-quality manufacturing capacity, for customers to complete the design, procurement, manufacturing and other real sense of the "one-stop" service, to build a complete PCBA ecological chain, and ultimately realize the company's overall product competitive advantage.
Q: What are the advantages of Polyester PCB?
A: Flexible PCBs are lightweight, can withstand high temperatures, and can be folded without damage. They save space and can fit into tiny or irregularly shaped spaces. They also reduce the need for wires and connectors, which helps reduce overall system failure rates.
Q: What are the applications for flexible PCB manufacturing?
A: They are typically used in devices where space is limited or where the board needs to flex during installation or undergo frequent flexing during operation. Applications include smartphones, wearable devices, LCD monitors, implantable medical devices, and automotive electronics.
Q: What are the challenges of flexible PCB manufacturing?
A: Challenges include controlling board flexibility, handling and aligning thin, flexible substrates during manufacturing, and ensuring board reliability, especially at folds.
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