Imaging Technology through Laser Direct Method and its Benefits Elucidated
In the realm of Printed Circuit Board (PCB) manufacturing, a significant shift is underway. Traditional methods, which have long relied on photolithography, are being replaced by a newer, more efficient technique: Laser Direct Imaging (LDI).
For years, photolithography has been the cornerstone of PCB production. This process involves the use of photographic masks called phototools and ultraviolet (UV) light to harden a photoresist layer on the board. However, LDI marks a new era, eliminating the need for physical masks by using a computer-controlled laser to directly write circuit patterns onto the photoresist [1][3][4].
The LDI process includes several steps, such as scrubbing, lamination photoresist, loading CAM files, laser printing, etching, photoresist strip, and drying. Compared to photolithography, LDI offers superior registration accuracy, particularly for multi-layer PCBs, achieving sub-micron alignment tolerances [3]. It also facilitates faster production by removing mask fabrication and manual alignment, streamlining the process and reducing turnaround times [3].
LDI's laser-based approach handles fine features better, supporting line widths down to 25 micrometers or less, which is more challenging with conventional photolithography [4]. Moreover, LDI provides sharper images with enhanced resolution, precision, and consistent imaging compared to photolithography, unaffected by fluctuations in temperature and humidity [2].
In traditional photolithography, UV light causes a change in the photoresist material, either hardening it or making it more soluble, depending on whether it is a negative photoresist or a positive photoresist respectively. In contrast, LDI requires a fast-acting photoresist, which is a significant advantage in terms of speed and efficiency [5].
The Automatic Optical Inspection (AOI) process in conventional PCB photolithography involves checking the existing circuit board against the circuit patterns that are present in the system. However, LDI's precision and consistency eliminate the need for such post-production checks, further streamlining the manufacturing process.
In conventional PCB photolithography, the photo-sensitive film called photoresist is placed on core surfaces at 75-80 °C to bind it to the core surface. After the imaging process, the photo-sensitive material is removed in the photoresist strip process. Subsequently, etching is a process where unwanted copper on the board is removed. Finally, drying the core/CCL after removal of the photo material is necessary.
Photolithography also involves the use of films in photo tools, with registration taking place through tooling holes. In contrast, LDI layer registration uses colliding laser beams from the top and bottom sides of the board, ensuring zero-zero registration, with variations up to 5-microns depending on the flatness of the board [6]. In photolithography registration, there are 15-20-micron variations, while in LDI registration, there is a 5-micron variation depending upon the flatness of the board.
The use of LDI in PCB manufacture is increasing and showing no signs of slowing down. Its digitally controlled, faster, and more precise imaging method without the physical limitations and error sources of traditional photolithography makes it particularly suitable for complex, high-density multilayer PCB designs [3][4][2]. As technology continues to advance, it's clear that LDI will play an increasingly important role in the future of PCB manufacturing.
[1] "Laser Direct Imaging in PCB Manufacturing." Nano Dimension. N.p., n.d. Web. 22 Mar. 2023.
[2] "Laser Direct Imaging for High-Resolution PCB Fabrication." Printed Circuit Design & Fabrication. N.p., n.d. Web. 22 Mar. 2023.
[3] "The Advantages of Laser Direct Imaging for PCB Manufacturing." PCB Solutions. N.p., n.d. Web. 22 Mar. 2023.
[4] "Laser Direct Imaging (LDI) Technology in Printed Circuit Board Manufacturing." Electronic Design. N.p., n.d. Web. 22 Mar. 2023.
[5] "Laser Direct Imaging for PCB Manufacturing: A Comprehensive Guide." I-Connect007. N.p., n.d. Web. 22 Mar. 2023.
[6] "Laser Direct Imaging vs Traditional Photolithography in PCB Manufacturing." Circuits Assembly. N.p., n.d. Web. 22 Mar. 2023.
Data-and-cloud-computing technology plays a crucial role in the innovative realm of Laser Direct Imaging (LDI) in PCB manufacturing. The LDI process relies on computer-controlled systems for laser printing, loading CAM files, and ensuring registration accuracy, demonstrating the effectiveness of advanced technologies.
The streamlined process of Laser Direct Imaging (LDI) significantly reduces turnaround times and eliminates the need for post-production checks, showcasing the potential benefits of cloud computing and data processing in the PCB industry's future.
