Efficient Strategies for Economizing HDI Boards Use
In the world of electronics, the debate around High-Density Interconnect (HDI) PCBs and their worth in terms of cost is a hot topic. Atar Mittal and Steve Arobio, directors of PCB manufacturing and design respectively, have been examining the use of HDI designs that aim to avoid buried vias, despite the potential difficulties in manufacturing.
Application Requirements and Benefits
HDI PCBs offer significant advantages, enabling miniaturization and higher component density. This leads to smaller, lighter, and more powerful devices, which are crucial in industries like consumer electronics, medical devices, aerospace, telecommunications, and automotive where size, weight, and performance are paramount [1].
Manufacturing Complexity and Costs
While HDI PCBs offer numerous benefits, they also come with increased manufacturing complexity and costs. Advanced manufacturing techniques such as laser drilling for microvias, sequential lamination, and precise imaging are required [1][2][4]. Specialized materials like thin laminates and exotic surface finishes further raise expenses [1][2].
Design Complexity
HDI designs are intricate, necessitating experienced engineers due to complex via structures and tight tolerances. This complexity increases design time and the risk of errors, impacting overall cost and manufacturability [1][2][4].
Material Selection
Premium materials tailored for high-speed signals, thermal management, or environmental resilience may be essential for HDI PCBs in demanding applications (5G, aerospace), but significantly add to cost [2][4].
Layer Count and Via Structures
Increasing layer count and using stacked microvias or via-in-pad structures also multiply fabrication steps and cost. Each additional layer introduces lamination cycles and alignment challenges [2][4].
Order Volume and Production Scale
Small prototype runs are disproportionately expensive due to non-recurring engineering (NRE) costs and setup complexity. Larger production volumes can mitigate per-unit costs substantially [2][4].
Cost-Performance Trade-offs
Early design consultation with manufacturers can help optimize via structures, layer stacks, and panelization to keep costs manageable while meeting performance goals [2][4]. Avoiding over-specification of features reduces unnecessary expenses [2].
New Developments and Recommendations
Nelco is continually investigating resin formulations, glass, and fabric constructions that would improve the manufacture of HDI architectures. The firm recently introduced a new material, N4800-20 SI, which it recommends in place of N4000-13 SI for HDI PCB manufacture [5].
Steve Arobio advises designers to concentrate on yield from the beginning when developing a stackup [6]. For HDI fabrication, a material must be dimensionally stable, easily machinable, and able to survive multiple laminations [7].
If BGAs with a ball pitch of less than 0.5 mm are involved, it is recommended to consult with a board manufacturer before commencing the layout [8].
Comparing Materials
The three materials compared in the discussion are Isola FR408HR, Nelco N4000-13 SI, and Panasonic Megtron 6.
FR408HR has a higher dielectric constant and higher loss factor than both N4000-13 SI and Megtron 6, but it is cheaper in price [9]. Megtron 6 has a slightly higher average Dk value than Nelco 4000-13 SI, from 1GHz to 10GHz, but a much lower Df [10].
The Economy of Buried Vias
Steve Arobio and Atar Mittal have also discussed the economy of buried vias in HDI technology. In some cases, buried vias can offer cost savings by reducing the number of drilling operations and lamination cycles [11].
Yield and Cost Considerations
Yield is the paramount cost consideration in PCBs, and somebody pays for it. In prototype fabrication, a shop may have to absorb waste if it needs to make more boards than ordered to deliver the correct number [12].
In conclusion, choosing HDI PCBs is justified primarily when device miniaturization, high performance, and advanced functionality are critical and cannot be met by traditional PCB technology, despite the higher manufacturing and design costs. The decision should weigh these technical gains against cost, complexity, production volume, and material requirements to ensure value for the specific application [1][2][4].
[1] The Printed Circuit Designer's Guide to... High-Density Interconnect PCBs
[2] Understanding HDI PCB Design and Fabrication
[3] High-Density Interconnect (HDI) PCB Technology
[4] Designing High-Density Interconnect (HDI) PCBs
[5] Nelco Introduces New HDI Material N4800-20 SI
[6] Steve Arobio: Designing for Manufacturability
[7] HDI PCB Fabrication Challenges and Solutions
[8] Designing HDI PCBs for Fine-Pitch BGAs
[9] Comparing HDI PCB Materials: FR408HR vs N4000-13 SI vs Megtron 6
[10] Megtron 6 vs N4000-13 SI: A Comparative Analysis
[11] Buried Vias in HDI PCBs: Cost Savings and Challenges
[12] Managing Prototype Fabrication Costs
- In the realm of technology and general news, the financial implications of HDI PCBs in various industries, such as consumer electronics, medical devices, aerospace, telecommunications, and automotive, are being scrutinized due to their ability to minimize size, weight, and enhance performance.
- The controlled impedance of HDI designs in lifestyle products can lead to increased costs, given the need for advanced manufacturing techniques like laser drilling for microvias, sequential lamination, and precise imaging, as well as specialized materials like thin laminates and exotic surface finishes.
- The adoption of HDI designs in finance and industry sectors requires careful consideration of the economic impact, as the intricate designs necessitate experienced engineers, which increases design time and the risk of errors, ultimately affecting the overall cost and manufacturability.
