Hong Kong high-price recycling of circuit board (PCB) panels, collection of returned Hong Kong circuit boards, nationwide return of circuit boards

Timeline of PCB (Printed Circuit Board) Technology Development

1.The embryonic stage and the exploration period

· Early 20th century - 1903： German inventor Albert Hansen proposed the basic concept of laying metal foil lines on an insulating board and achieving inter-layer connections through drilling， which was regarded as the earliest prototype of PCB.

· 1920s-1930s: American inventors such as Charles Ducasse proposed the method of printing (electroplating) conductive lines on an insulating substrate and first used the term "printed circuit". This period was mostly experimental, such as in radios.

2. Practicalization and War-Driven Period

· 1940s (during World War II)： PCB technology was first applied on a large scale. The United States used it in proximity fuses and other military equipment， using vacuum tube components and connecting them through manual soldering. This established the value of PCB in the miniaturization and reliability of electronic devices.

3. Industrialization and Standardization Period

· 1947： The United States National Bureau of Standards developed the "immersion soldering method"， laying the foundation for automated production.

· 1950s： Single-sided boards became mainstream.

· Dr. Paul Eisler's patent technology (copper foil etching method) was widely recognized and commercialized， hailed as the "father of printed circuit boards".

· The commercialization of transistors replaced vacuum tubes， making electronic devices smaller and further driving the demand for PCBs.

· 1960s： Double-sided and early multilayer boards emerged.

· With the invention of integrated circuits， the density of components increased， and double-sided wiring became necessary.

· Through-hole metallization technology matured， achieving reliable electrical connections on both sides of the double-sided board.

· Wave soldering technology was popularized， achieving automated soldering.

4. High Density and Complexity Period

· 1970s-1980s： Multi-layer board technology developed rapidly.

· Personal computers， aerospace， and complex industrial equipment required higher integration， with 4-layer， 6-layer， and even more layers of PCB becoming the norm.

· Surface Mount Technology (SMT) began to sprout， preparing for further miniaturization.

· 1980s-1990s： SMT Revolution.

· SMT fully matured and replaced through-hole assembly technology as the mainstream. Component sizes shrank dramatically， and PCB design moved towards high density.

· Design for Manufacturability and computer-aided design software began to be widely used.

5. Modern High Density Interconnection and Advanced Packaging Period

· Since the 1990s： High-density interconnection technology has become the main player.

· Micro holes， blind holes， and buried holes technologies emerged.

· Layered method is widely used to manufacture high-numbered， high-density motherboards (such as mobile phone and computer CPU motherboards).

· Early 21st century： Lead-freeization.

· Driven by environmental regulations (such as the EU RoHS)， lead-free solder and welding processes became global standards.

· 2000s-2010s： Continuous innovation in materials and processes.

· High-frequency materials (such as polytetrafluoroethylene) are used in 5G， radar.

· Any-layer HDI， buried component technology emerged.

· 2010s to present： Integration with advanced packaging.

· Class load boards (between standard PCB and IC load boards) are used in high-end mobile phone processors.

· Flex-rigid combined boards are popular in wearable devices and foldable phones.

· Fan-out panel-level packaging and other technologies blur the boundaries between PCB and chip packaging.

6. Current Trends and Future Prospects

· Higher Density and Integration： Line width/spacing continues to shrink， moving towards 20µm and below.

· New Materials： Application of lower-loss high-speed materials， heat-conductive metal substrates， etc.

· New Processes： Additive/semi-additive processes are more precisely used to manufacture ultra-fine lines.

· Electronic and Structural Integration: "Functionally Integrated" PCB, integrating antennas, sensors, power management, and even optical components.

· Intelligent Manufacturing and Simulation: AI-assisted design, industrial internet for intelligent manufacturing, simulation software predicts signal integrity and thermal performance in advance.

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