Materials processing of polymers presents unique challenges for medical device manufacturers. It requires forming features with exceptional precision in heat sensitive materials while still maintaining their chemical and mechanical integrity.
Lasers have already established themselves as indispensable tools for a variety of polymer welding, cutting, drilling, marking, and surface texturing tasks in medical device production. Lasers offer a variety of advantages for polymer micro-machining, including non-contact processing that avoids mechanical deformation and the ability to remove material with micron level precision.
(A) The edge of a polycarbonate blind disc machined with a nanosecond laser displaying excessive melting.
(B) The edge of a polycarbonate blind disc machined with an ultrafast laser displaying virtually no melting.
Two of the most commonly employed technologies for polymer processing are nanosecond pulsed and ultrafast pulsed lasers (also known as ultrashort lasers). While ultrafast lasers deliver unmatched quality, they also come with higher costs and slower processing speeds.
In contrast, nanosecond lasers offer higher speed processing at a more economical price. But they tend to produce a larger heat affected zone (HAZ) and struggle to achieve the same level of precision.
This means manufacturers must choose the right laser to maximize quality, throughput, and cost-efficiency for a specific polymer processing task. Here we’ll learn how to do that.
Polymer Processing Challenges
Polymers are essential materials for modern medical devices because they offer a combination of desirable mechanical properties, chemical resistance, and biocompatibility – and they are often quite cost-effective. Plus, their physical properties can be engineered to optimize them for specific uses.
But these same traits complicate high-precision fabrication. Here’s are some of the challenges presented by the polymers most widely used in medical devices.
PEEK & PTFE (Teflon): These materials are chemically resistant and thermally stable but difficult to machine cleanly. PTFE in particular resists most laser wavelengths due to its inertness and pue absorption.
Polyethylene & Polyurethane: Polyethylene and polyurethane are thermally sensitive, making them prone to melting, charring, or deformation when exposed to prolonged laser energy.
Pebax®: Used extensively in flexible tubing, Pebax® and materials like it are vulnerable to heat, which can cause stretching and distortion and complicate micro-machining tasks.
Kapton® (polyimide): Kapton® and other polyimides are useful in multilayer/flexible circuits. Laser cutting can be used to create burr-free edges to prevent delamanation or dielectric damage, but adhesive interlayers increase the risk of charring.
Regardless of the polymer, the primary concerns around laser processing are minimizing heat-affected zone (HAZ), avoiding debris and fumes, and ensuring clean edges for reliable device performance.
Laser-Polymer Interactions
The key to optimizing results is to match laser parameters to the material characteristics. And these characteristics vary widely by material.
The first step is to understand the underlying physics of how lasers interact with these materials. Laser-material interaction is defined largely by power, pulse duration, wavelength, and material absorption characteristics. These interactions are significantly different for polymers than for metals, semiconductors, or ceramics.
Lasers with nanosecond (billionths of a second) pulse durations deliver their energy over a sufficiently long duration for heat to diffuse into the surrounding material. This is acceptable for metals as their free electrons allow them to readily conduct and dissipate heat without damage.
However, polymers lack these free electrons and are poor thermal conductors. They tend to degrade, melt, or discolor when subjected to extended heating. As a result, nanosecond pulses can cause melting and reflow at the edges, resulting in burrs, debris, and a wider HAZ.
Ultrafast lasers produce pulses with durations measured in the picosecond (trillionths of a second) or femtosecond (quadrillionths of a second) range. Their energy is introduced so rapidly that material is ionized and ejected before heat can transfer into the part. This results in a process known as “cold ablation.”
Because the ultrafast laser vaporizes or photo-dissociates material rather than melting it, it significantly reduces thermal impact. The result is high-precision features with clean edges and minimal contamination.
Choosing the Right Laser
Choosing the appropriate laser technology for a specific application is a balance between quality, speed, and cost. Nanosecond lasers are often the default choice for manufacturers aiming to maximize throughput and minimize equipment costs. Since these lasers produce more heating, they’re better suited to polymers that are less heat-sensitive like polyethylene and polyurethane.
Nanosecond lasers are also suitable for tasks such as basic marking or cutting where minor edge imperfections or a modest HAZ will not compromise device performance. Their ability to process quickly and affordably makes them well-suited for operations where speed and cost-efficiency outweigh the need for micron-level precision.
Ultrafast lasers are all about precision and minimal HAZ. They’re especially useful with delicate polymers like PEEK, Teflon, and PEBAX. These are all prone to deformation or contamination when exposed to thermal energy. Ultrafast lasers produce clean, sharp edges in these materials with virtually no HAZ and minimal debris, reducing or eliminating the need for post-processing.
However, the advantages of ultrafast lasers come at a cost. These tools are more expensive and usually deliver lower throughput. This may limit their viability in high-volume production environments. Furthermore, these tradeoffs usually become more significant as pulse duration decreases – picosecond lasers are usually more productive and economical than femtosecond lasers.
Thus, the key to optimizing laser processing of polymer medical devices usually lies in choosing the longest pulse duration that still meets the application quality requirements. For simple features and heat tolerant materials, nanosecond lasers may be sufficient and far more economical. But when dealing with high-precision features, challenging geometries, or thermally sensitive materials, ultrafast lasers are often indispensable.
It is common for manufacturers to use a hybrid approach, even within the same product or production line. This entails employing nanosecond (or even continuous wave) lasers for less sensitive tasks and reserving ultrafast lasers for more critical features. This strategy ensures that product quality is not compromised where it matters most while still maintaining cost and production efficiency across the broader workflow.
Typical Polymer Medical Device Applications
Medical device manufacturers currently use lasers for a broad range of critical polymer applications. For example, ultrafast lasers are the go-to choice for drilling precision holes in multi-lumen catheter tubing or forming microfluidic channels in diagnostic platforms. For these applications, micron-level accuracy and thermal cleanliness are mandatory. The cold ablation processing of ultrafast lasers also makes them ideal for devices used in vascular or neuro applications where small geometries and smooth edges are essential.
Nanosecond lasers are frequently used for cutting or trimming components like catheter shafts. Here some degree of thermal effect is tolerable, and speed is critical. They are also widely used for marking. This includes simple part IDs, batch codes, or logos on non-critical plastic housings.
UDI marking is a key application where lasers offer an advantage over other technologies. Currently, UV nanosecond lasers are the industry workhorse for UDI marking. The comparatively short UV wavelength is readily absorbed by plastics, producing crisp, high-contrast marks with minimal thermal stress. This provides an ideal balance of permanence, legibility, and processing speed.
For UDI marking in higher-value applications (where surface integrity is paramount), manufacturers are increasingly using ultrafast lasers. Their ability to perform “cold” ablation creates marks that withstand multiple sterilization cycles and remain scannable without developing debris or damage.
Surface preparation for adhesive bonding or coating adhesion is another area where both ultrafast and nanosecond lasers find utility. For large-area texturing, nanosecond lasers may suffice. But for delicate or finely tuned surfaces, ultrafast excels by delivering uniform results without damaging the material.
Getting Started with a Laser Solution
Polymers are the backbone of many innovative medical devices but processing them to high standards is no simple task. Laser technology – when correctly matched to the application – provides an ideal combination of precision, repeatability, and cleanliness. By understanding the nuances of laser-material interactions and strategically deploying both nanosecond and ultrafast lasers, manufacturers can meet rising quality expectations while staying competitive in an increasingly cost-conscious industry.
Exploring a laser solution for welding, cutting, drilling, marking, or texturing polymer medical devices? Getting started is easy – send us a sample, visit one of our global application labs, or just tell us about your application.
