In times of material shortages and increasingly strained supply chains, flexibility in PCB material selection has become more important than ever. But what may initially appear to be a simple material substitution can have significant implications for design, manufacturing, certifications, and long-term supply security.
Because the global PCB market changes and leading laminate suppliers shift focus toward AI-driven, high-speed materials, the supply of standard FR4 material is gradually tightening. To reduce the risk of our customers facing material shortages, we are testing and evaluating alternative materials from local suppliers. These newer materials have matured and now offer reliable, repeatable performance at the required levels.
PCB material is a complex construction, and it is not as easy as just exchanging one material to another and assuming that everything continues as before. Even when two materials appear similar on paper or meet the same IPC-4101 slash sheet requirements, differences in electrical, thermal, mechanical, and processing characteristics can influence the final PCB performance and long-term reliability.
In this blog post, we highlight the key factors to weigh when evaluating a material change.
Layer stack-up: The foundation of PCB performance
A printed circuit board is built upon a carefully designed layer stack-up consisting of various materials, including core materials and prepregs.
We have made a design guideline for Stackups and impedances that might be helpful. Download it here >
Differences in material properties such as thickness, resin content, and dielectric constant can affect the overall stack-up. As a result, changing the base material often requires a review and adjustment of the layer structure to maintain the desired electrical and mechanical performance. In addition, the availability of equivalent core and prepreg thicknesses should be verified. Different material suppliers may offer similar laminates but not necessarily the same dielectric constructions, which can affect overall board thickness, copper balancing, and impedance performance.
Thermal performance and reliability considerations
Material substitutions should also be evaluated from a thermal and reliability perspective. Key properties such as glass transition temperature (Tg), decomposition temperature (Td), coefficient of thermal expansion (CTE), and thermal conductivity can differ significantly between materials.
These differences may influence soldering performance, thermal cycling capability, plated through-hole reliability, and overall product lifetime, particularly in automotive, medical, industrial, and power electronics applications.
Maintaining controlled impedance requirements
Controlled impedance is a critical requirement in many high-speed applications. A change in PCB material can affect electrical properties and directly impact signal integrity performance. For high-speed digital and RF applications, engineers should evaluate not only dielectric constant (Dk), but also dielectric loss (Df) across the relevant frequency range. Materials with similar nominal Dk values may exhibit significantly different signal loss characteristics at higher frequencies.
To minimize risks, it is important to inform your PCB manufacturer that there are impedance-controlled traces in the design, allow the manufacturer to select suitable materials for the stack-up, and adjust trace widths and spacing, if necessary, based on manufacturing capabilities and material properties.
An experienced PCB producer can optimize the layer stack-up and modify conductor geometries to ensure that impedance targets continue to be met.
Impact on qualification and certification
Material substitutions can affect existing qualifications and certifications. Therefore, it is important to consider whether the certification of the original base material remains valid and if the combination of base material, solder mask, and conformal coating is still qualified.
Not every material combination has been tested and approved. Furthermore, some end customers may have qualified the complete PCB construction rather than only the laminate itself. In such cases, even a technically equivalent material may require formal customer approval prior to implementation.
In some cases, additional qualification activities or approval processes may be required before production can continue.
Do not overlook UL approval
UL compliance is another important aspect that may be affected by a material change, and it is therefore important to check that the alternative material has the required UL approval and be aware that the UL marking on the PCB may change. In some cases, the PCB flammability designation, UL file number, or approved material combinations may differ, requiring additional documentation, customer notification, or requalification activities. For products intended for regulated markets, these factors should be discussed with your PCB supplier early in the process.
When is requalification necessary?
Depending on the application and customer requirements, a material change may require a new qualification process. This is often required when electrical properties are affected, existing certifications are impacted, or the customer specifications or industry standards require revalidation. Particular attention should be given to highly regulated industries such as automotive, aerospace, rail, and medical technology, where material substitutions frequently trigger formal change management and qualification requirements.
Early assessment of these requirements can help avoid delays during production ramp-up.
Availability and supply security matter more than ever
When the market is volatile, having a robust material strategy is important. Material shortages and extended lead times can delay development and production schedules. To reduce supply chain risks, we suggest assessing long-term supply security, and evaluating and approving alternative materials in advance together with your PCB supplier and qualify multiple material options whenever possible.
Interested in learning more about the current changes in the PCB market?
IPC-4101 slash sheets
One effective way to increase flexibility is to specify an IPC-4101 slash sheet rather than a specific commercial material. Instead of calling out materials such as Isola IS415 or Panasonic R-1755V, designers can specify the applicable IPC-4101 material class. This approach offers several advantages:
- Any qualified material meeting the IPC-4101 specification can be used.
- PCB manufacturers gain greater flexibility in material selection.
- Risks associated with long lead times and material shortages are reduced.
- Overall supply security is improved.
This strategy provides greater independence from individual material suppliers while helping to ensure production continuity.
Conclusion
Changing PCB materials involves far more than replacing one laminate with another. The effects on layer stack-up, impedance control, certifications, UL compliance, qualification processes, and supply chain reliability must all be carefully evaluated.
At the same time, current market challenges present an opportunity to rethink material strategies and adopt more flexible approaches such as IPC-4101 slash sheet specifications. Organizations that proactively address these considerations can improve supply security, minimize manufacturing risks, and avoid costly surprises later in the product lifecycle.
Do you have any material related questions? Don’t hesitate to contact us, we are happy to help.