Precision Without Contact: How Laser Drilling and Laser Marking Address Two Fabrication Challenges in RF and Microwave Design

RF and microwave engineers know that the gap between a design that simulates well and a component that performs well in the field often comes down to manufacturing. Two processes that don't always get attention in that conversation are laser drilling and laser marking.

Accumet Engineering, based in Devens, Massachusetts, has spent more than five decades processing advanced ceramic substrates and precision components for aerospace, defense, and electronics manufacturers. The company's laser capabilities — cutting, drilling, welding, ablation, and marking — are built around a single facility where laser processing and ceramic finishing work together rather than in sequence across multiple vendors.

Laser Drilling: The Via Problem in Ceramic Substrates

Through-holes and vias in ceramic substrates — alumina, aluminum nitride, quartz — are a routine part of RF and microwave packaging. Ground connections, thermal paths, and signal feeds all depend on them. But producing those features cleanly in brittle ceramic materials is a different problem than drilling metals or FR4.

Why mechanical drilling falls short in ceramics:

• Tool contact generates stress fractures and edge chipping
• Tool wear introduces variability from hole to hole
• Tight tolerances are difficult to maintain consistently 

Laser drilling avoids those problems. With no tooling contact, there's no mechanical force and no wear-driven variability. Accumet's laser drilling achieves:

• Hole diameters as small as 0.005"
• Diametric tolerances as close as ±0.001"
• Feature-to-feature tolerances that are non-cumulative, which is critical for dense via layouts

Post-Drilling Surface Preparation

After drilling, Accumet re-laps and re-polishes the substrate to remove surface slag and clear entrance and exit slag from each hole. This step directly affects metallization adhesion and circuit yields.

For thick film, thin film, or as-fired substrates going into production, the surface condition at the via is consequential. Slag at the hole entrance affects how conductor layers adhere, which changes how the circuit performs.

“Re-lapping after laser drilling is an extra step, but it's one our customers always benefit from,” said Diana Toruno, General Manager at Accumet. “Substrate surface condition at the via directly affects how well conductor layers adhere, and that's not a variable you want to leave to chance in a high-frequency circuit.” 

The practical result is a single-source workflow: substrates can be lapped, polished, laser drilled, and re-finished without leaving the facility, which has implications for traceability as much as lead time.

Laser Marking: Permanent Identification for RF and Microwave Components

Serialization and traceability requirements have grown significantly in aerospace and defense programs. ITAR-controlled components need permanent, legible identification that survives cleaning and sterilization cycles, thermal cycling across operating extremes, and the handling that production and field environments involve. Traditional marking methods each carry limitations that laser marking addresses.

The Marking Process

Using YAG and CO₂ systems, laser marking produces permanent marks directly in the material surface rather than deposited on top of it. On metals, ceramics, and select plastics, the result is a mark that won't flake, erode, or develop the corrosion byproducts that older marking techniques sometimes leave behind.

Accumet's marking capability covers flat, curved, and round surfaces using computer-controlled rotary optics, which is relevant for coaxial hardware, stainless steel tubes, and cylindrical RF connectors where flat-bed systems can't reach. Specifications include:

• Marking field diameters up to 6 inches
• Character heights from 0.008" to 4.00"
• Barcodes, serial numbers, alphanumeric sequences including OCRA-A variations
• 0.0008" programmable resolution

Marking vs. Etching vs. Engraving

These terms are often used interchangeably, but they produce different results:

• Laser marking — used for metals requiring serial or model numbers; non-contact, no material removal
• Laser etching — removes material to create labels or identifiers on laminates, ceramics, or plastics
• Laser engraving — deeper removal, typically for panels, plaques, or decorative work

The right choice depends on the material, the required contrast, and how the part will be used in service.

From Substrate to Finished Part

Both processes benefit from being performed in the same facility as substrate finishing work. When drilling is followed by re-lapping in the same controlled environment, and when marking is done on parts already dimensionally verified, the quality chain is shorter and easier to document.

Accumet operates under AS9100 and ISO 9001 certifications and maintains ITAR compliance at its Devens facility. For aerospace and defense programs where traceability documentation is as important as dimensional conformance, that combination of precision laser processing, integrated ceramic finishing, and a certified quality system addresses the problem from raw substrate to finished, marked part.

As RF and microwave designs push into higher frequencies and tighter packaging envelopes, the tolerance windows on via geometry and component identification continue to narrow. For programs where dimensional accuracy and part traceability both have to be right, having those capabilities under one roof simplifies the path from design to qualified part.

Learn more about Accumet's laser drilling and laser marking capabilities at accumet.com, or contact the team to discuss substrate processing requirements.