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Connect the Dots: Evolution of PCB Manufacturing—Lamination

When I wrote The Printed Circuit Designer's Guide to...™ Designing for Reality, it was not a one-and-done effort. Technology is advancing rapidly. Designing for the reality of PCB manufacturing will continue to evolve. That’s why I encourage designers to stay on top of the tools and processes used during production, to ensure their designs capitalize on the capabilities of their manufacturing partner.

Specifications keep calling for smaller, more durable, and increasingly complex multilayer boards. The lamination process is a key production component for complex multilayer PCBs where multiple layers are needed to achieve desired functionality with a small footprint in tight spaces, often at high temperatures.

I believe designers benefit from a clear understanding of the materials and processes used during all aspects of production. When designing multilayer boards for manufacturability, understanding the manufacturing process downstream from your design will prevent headaches and costly delays. The lamination process also allows designers to improve the durability and functionality of the manufactured board, as well as potentially reducing materials cost and streamlining production.

The Evolving Lamination Process
Methods of fusing multilayer boards have come a long way. If you go back far enough, it involved the use of Masonite, rivets, and cardboard. The development of flame-retardant (FR-4) epoxy-glass materials led to better thermal management, reduced signal loss, and improved manufacturability. Polyimide paved the way for widespread flex and rigid-flex PCB design and manufacturing.

Advancements such as these (along with consistent incremental change) led designers to learn new tricks and techniques to ensure their designs are ready for modern manufacturing. We have seen the average multilayer PCB design transform significantly in recent years, driven by the increasing demand for boards that power compact and feature-rich electronic devices.

However, more layers equate to more materials, intricacy, and cost. Designers can’t simply pile one on top of another to reach the desired level of functionality. Additional layers create increased complexity and additional considerations, including signal integrity, heat, increased materials cost, and overall manufacturability. I encourage designers to carefully consider the optimum number for their design and focus on key design elements that can ensure an effective lamination process, control costs, and produce a reliable board:

• Avoid designs with excessive layers that increase costs without improving performance
• Design a symmetrical layer stack, paying attention to copper distribution and the thickness of non-conductive (dielectric) materials
• Accurately align the drill holes to the copper pads across multiple layers of the board, ensuring the through-holes align and connect the intended paths without creating an unreliable connection or short-circuits
• Stop me if you’ve heard me talk about this before: Design traces with consistent widths and spacing to maintain impedance control
• Another one you might be familiar with, if you regularly read my articles: Avoid unnecessary blind or buried vias that can create problems during production and increase cost
• Collaborate with your manufacturing partner about your stackup and material properties to prevent costly reworks

Designing for the Reality of UHDI PCBs
These design strategies will become more important as electronic devices increasingly rely on the most advanced boards. You can find ultra high density interconnect (UHDI) PCBs inside your phone, wearable, and PC. They enable more advanced products like medical devices and driver-assist systems in automobiles.

Cutting-edge UHDI technology pushes the limits of fabrication capabilities for PCBs and challenges designers to reduce both the footprint and thickness of their board designs. UHDI’s advanced miniaturization and integration pack a transformative amount of functionality in a small footprint. Though not new technology, the proliferation of UHDI into a broader array of devices represents a quantum leap for our industry. It is changing the fundamental method of manufacturing boards and creating the need for new manufacturing methods, equipment, chemistry, materials, and inspection capabilities.

Designing for the reality of manufacturing UHDI PCBs represents a new challenge for many of us. There will be a wide range of design considerations related to new, more advanced fabrication techniques, higher-performance materials, 3D integration methodologies, leading-edge thermal management solutions, and ultramodern simulation tools.

To learn more about how UHDI is shaking up PCB design and manufacturing, check out this recent Design007 feature article. For a deeper dive into this topic, listen to this episode of On the Line with…  where we also discuss the complexities of sequential lamination for high-density PCB designs.

A Quick Refresher on Lamination
This stage of manufacturing is where we fuse multiple layers of a PCB into a single board. The sequential lamination process used for multilayer boards involves layering copper and substrate materials, then applying heat and pressure to bind them together. Engineers laminate individual subsets of layers separately, then bond them together in subsequent cycles. The result is an electrically connected PCB. 

Read Matt’s book, The Printed Circuit Designer’s Guide to… Designing for Reality, or listen to his podcast here.

This column originally appeared in the September 2025 issue of Design007 Magazine.