[PCB manufacturing] PCB development trend: new technology, new materials, new challenges
In this paper, Patrick Riechel and Shane Noel of ESI discuss how to combine new laser technology with control functions to increase productivity and meet the challenges posed by new materials.
The popularity of mobile devices and the growing popularity of other wearable/portable electronics have created a number of challenges for manufacturers of flexible panels.Phones, tablets, and other personal devices can help people communicate, manage their time, and connect us to the Internet to provide information when and where we need it.Relying on sensors and technology in an increasing number of "smart" cars to ensure safe travel;Use iot devices to monitor and automate the world around us.Whatever the technology, the market is increasingly demanding that devices be smaller and more powerful, that they perform more functions, last longer, use less electricity, are more portable than their predecessors, and all on a lower cost basis.
Demand is being passed down the value chain, forcing manufacturers to rethink their processing capabilities, re-evaluate the processing technologies they use, and re-optimize the manufacturing processes they implement in production.Although there is no similar Moore's law in the field of flexible plate manufacturing, it is clear that manufacturers of flexible and rigid PCB need to attach great importance to innovation in order to keep up with the pace of development.They need to keep innovating and evolving, or they will lose out to their competitive peers.They need to focus on developing high yield and high yield processing capabilities for new materials, and on processing these materials on a smaller scale and with greater precision.
Technical overview of the last 5 years
Just five years ago, apple introduced the first apple watch.Meanwhile, amazon's Echo device is bringing voice-assisted technology to millions of homes.Google's Google glass and Oculus Rift bring virtual reality to the masses.These devices show significant advances in connectivity and the use of seamless data transfer in our daily lives.These and other subsequent devices depend heavily on the use of flexible plates.They provide the functionality that the market needs and satisfy the appearance of wearable and portable devices.
Around the same time, apple unveiled its latest flagship smartphone, the iPhone 6, with an LCD display, a single-lens camera and a 4G connection.At that time, the most common FPC material used in consumer electronics products was two-sided copper-coated flexible laminates. There were 12 light-meter copper foil and 25 light-meter polyimide dielectric films. More than 80% of the flexible circuits in common devices adopted this material structure.
Today, apple's iPhone 11 features an OLED display, face recognition technology, multiple cameras, wireless charging and a limited 5G antenna.The use of flexible drilling in consumer electronics has expanded, adding a wider range of structures and more challenging materials.This expansion of the material mix allows PCB board manufacturer to produce FPC with significantly smaller wire runs and through holes for tighter circuit design.It also implements new features that require a thicker conducting layer, such as high-current wireless charging.A lot has changed in the past five years.
With the portable equipment market demand for smaller and larger function continues to dominate, flexible plate design is becoming more and more complex, flexible plate manufacturers need to cope with the challenge of more and more, they need more and more attention with the process, can they use processing of materials as well as adopted by the technical innovation.They need to put more functions into a smaller space, which means that the design of flexible plates is bound to become more complex.The design with more conducting holes and smaller conducting holes has more restrictions on the smaller volume and space, and the stacking of thin materials has become the norm.
The continued move to smaller, denser devices has put pressure on PCB board manufacturer. Maintaining high yield in this environment requires the adoption of more sophisticated and advanced processing techniques and control methods, as well as the realization of maximum yield and minimum cost.
5G: case studies of material processing challenges
The application of 5G technology is a good example of how feature-rich new devices pose new challenges for PCB board manufacturer, especially when it comes to new, complex material combinations.Previous generations of portable devices made use of existing methods and techniques for handling tiny coaxial cables and relatively easy to handle dielectric materials such as polyimide.Today, much of the material needed for 5G capabilities and smaller packages on one of the most advanced smartphones is very different.
When balancing LCP against other low-k dielectrics (such as PTFE and modified or fluorinated polyimides), it is found that many ways of reducing its "K" value can also lead to unexpected problems in the production of the material, especially in mass production.For example, the thermal properties of many new types of dielectrics present unique processing challenges.When the heat exerted by the laser interacts excessively with the dielectric, the output is limited.The thermal impact can be minimized by implementing thermal mitigation techniques such as increasing the laser beam speed, making the laser pulses spaced longer, or by adding additional steps to the process so that the material has a sufficient cooling time.However, the impact of these mitigation techniques on total production needs to be considered.
Rising production costs
Another challenge for PCB board manufacturers is rising costs as new production facilities are added and existing facilities are expanded. The cost of putting in new equipment to support capacity growth has risen sharply in the past few years. Factors such as tighter environmental regulation have made expansion more expensive and time-consuming.While labor costs have been rising for some time in the United States and Europe, land and labor costs are also starting to rise sharply in countries that are now considered cheaper, such as China.
These trends have led many PCB board manufacturer to focus on optimizing existing facilities rather than adding new ones.This requires them to maintain or increase production while minimizing plant footprint and seeking higher productivity from existing systems.
Laser technology development
The first commercial UV laser is a lamp pump structure, which is characterized by a low repetition frequency of 1kHz to 5 kHz and a low average power of 1 W to 3 W.Although this performance curve met the application demand, these lasers were generally considered to be of low reliability and life.These lasers are no longer suitable for today's FPC material production environment of 7 days a week / 24 hours a day continuous operation and high yield of processing challenges.
Today, advances in laser technology have enabled the latest and most advanced diode-pumped solid state (DPSS) lasers and fiber optic UV lasers to operate at a repetition rate well above 100 kHz and at an average power of tens of watts, often lasting tens of thousands of hours.These new high performance lasers provide the basis for mass production of flexible circuits.However, they must be matched with similar high-performance beam transmission and control capabilities to achieve the high productivity, yield, quality and flexibility required to handle a wide range of materials and applications, typically used in consumer electronics.
Laser systems that meet today's challenges and technologies
Applying new laser technology to specific applications requires more than just the right laser.It also needs a suitable set of beam transmission and control technology to optimize the characteristics of the laser and its effect on the material.Not only are the machining challenges now increased, but the challenges associated with higher repetition rates and higher average power on today's most advanced lasers have also increased.
Optimization of a wide range of materials and high power lasers
Machining thick and thin material structures with a range of thermal properties and a high capture layer thickness with a high yield laser has been a challenge.At the same time, integrating high repetition rate, high average power lasers also maximizes productivity, making it more difficult to meet this challenge.The ideal laser system provides an improved method to reduce heat accumulation and laser energy variation in the workpiece (figure 1).
Combining high repetition rate laser technology with faster beam control, such as ESI's AcceleDrill™ technology, enables better thermal management and minimizes the impact of heat on materials.This degree of control of the beam allows the fabrication of new materials that are more prone to thermal problems (such as layering, dielectric, or adhesive etching) because increasing the beam speed enables sufficient pulse spacing to avoid excessive heat accumulation (figures 2 and 3).
Natural laser energy fluctuations must be reduced during laser processing to ensure optimum quality and yield.This is especially important in sensitive depth control applications, such as blind hole machining where the bottom pad is thin, prone to damage or layering.This is also important in applications where you can easily process extremely thin dielectric (such as 15 livm or thinner), because this type of dielectric allows only a very small margin of error, otherwise it will damage the underlying copper.The best way to avoid this energy fluctuation involves real-time monitoring and compensation of laser energy during processing, using ESI Precision Pulse ™ technology.
Solve the problem of rising production cost
As the premium for factory floor space and the cost of adding capacity rise, productivity becomes a priority.Systems that dramatically increase production can delay the need to add more systems, enabling PCB board manufacturers to avoid the costs associated with expansion, such as acquiring new land, plant space, licenses, and resources.The new system can reach the capacity of the previous generation with fewer units.Reducing the number of machines required also reduces overhead costs in terms of resource consumption and personnel requirements.
As mentioned earlier, increasing the productivity of a laser system can be achieved not only by the efficient use of a high-power laser, but also by reducing the unproductive time spent moving a laser beam between the two features.In addition, the preparation to start laser processing, such as alignment of features on the workpiece, maintenance of the system, will also add additional processing time.
Enhanced beam positioning, such as ESI's Third Dynamics ™ technology, reduces the time required to move a laser beam between features to be processed on the workpiece and is a way to minimize unproductive movement time.Another recent development in beam control can greatly improve the moving time of the laser beam in machining requiring multiple effective spot sizes, such as blind hole machining.
The ability to instantaneously shift the laser focus to change the size of the effective laser spot, such as ESI's DynaClean ™ capability, eliminates the need to pass a beam of light through each artifact's features twice -- once in focus and once out of focus.The effective result was a 50% reduction in movement time.
The advanced proportional compensation algorithm, coupled with the most advanced visual capabilities, can reduce the number of necessary points to meet a given process accuracy goal.In extreme cases, this ability can reduce machining time by several minutes, especially for work pieces with curved shapes.
Finally, the combination of robust system design and robust process development can significantly reduce maintenance time and downtime, thereby improving the overall productivity of the system.Precision mechanical, optical and systems engineering by reputable and experienced laser system manufacturers can significantly reduce the amount of maintenance required for laser systems, especially the high-power UV laser systems that dominate the flexible laser processing industry.Also, effective laser and optical protection mechanisms are critical for such UV laser systems.These measures extend the service life of the laser and optical elements while reducing the preventive maintenance downtime associated with cleaning and replacing the laser and optical elements.
conclusion
As the global demand for technology products continues to grow and the pace of change continues to accelerate, it is difficult for PCB board manufacturer to see the future clearly and understand what challenges they will face next.However, the only clear strategic tool for effectively responding to and profiting from new needs will be the ability to innovate.With the advent of the next generation of technology, mastering the latest technologies and processes is the best way to stay competitive in a competitive market -- to adapt to change without change.
