1.5mm PCB: The Often Overlooked Standard Thickness Explained

If you’ve ever browsed PCB thickness options and wondered whether 1.5mm PCB is a legitimate standard or just a rounding error, you’re not alone. This thickness sits in a confusing zone between the commonly cited 1.57mm historical standard and the widely used 1.6mm modern standard, leaving many engineers uncertain about what they’re actually getting.

Here’s the straightforward answer: 1.5mm PCB is absolutely a standard thickness offered by manufacturers worldwide. It appears in official thickness charts from major fabricators and represents a practical option for designs where every fraction of a millimeter matters. The confusion stems from how the original imperial measurement (0.062 inches) translates to metric, and how PCB manufacturing tolerances blur the lines between adjacent thicknesses.

This guide cuts through the confusion surrounding 1.5mm PCB, explains its relationship to 1.57mm and 1.6mm, and helps you decide when specifying this thickness makes sense for your project.

Understanding the 1.5mm vs 1.57mm vs 1.6mm Confusion

The PCB industry’s thickness standards originated in the United States using imperial measurements. The original standard was 1/16 inch, which equals exactly 0.0625 inches or 62.5 mils. When converted to metric, this becomes 1.5875mm, which different manufacturers round differently:

This single imperial standard has spawned three different metric labels, all referring to essentially the same thickness class. When you order a “1.6mm” board from most fabricators, you’re getting the same thing as their “1.57mm” or “1.5mm” option, just labeled differently.

Why Different Manufacturers Use Different Numbers

Regional preferences and rounding conventions explain the variation:

Asian manufacturers (China, Taiwan, Korea) typically round to 1.6mm, which has become the dominant global standard due to Asia’s manufacturing volume.

European manufacturers often reference 1.5mm or 1.55mm in their specifications, staying closer to the exact metric conversion.

North American sources sometimes cite 1.57mm (the precise conversion) or stick with imperial 0.062″.

Historical documents and older specifications frequently mention 1.5mm as the baseline standard.

The practical result? A board labeled “1.5mm” from one manufacturer may measure identically to a “1.6mm” board from another. The tolerance windows overlap significantly.

Is 1.5mm PCB Actually Standard?

Yes. Multiple reputable sources list 1.5mm PCB as a standard thickness option:

The inclusion of both 1.5mm and 1.6mm in these lists isn’t redundant. It acknowledges that some customers specifically need the slightly thinner 1.5mm specification, while others want the rounder 1.6mm number. Fabricators stock core materials to accommodate both.

1.5mm PCB vs 1.6mm: Does the Difference Matter?

The 0.1mm difference between 1.5mm PCB and 1.6mm PCB seems trivial, but context determines whether it matters:

When 0.1mm Actually Matters

Enclosure fit: If your mechanical design has tight tolerances and 1.6mm barely fits, specifying 1.5mm provides margin. The worst-case 1.5mm board (1.6mm at +tolerance) equals the nominal 1.6mm specification.

Connector compatibility: Some edge connectors specify thickness ranges. A connector rated for 1.4-1.6mm works better with a 1.5mm nominal than 1.6mm nominal, since you won’t risk exceeding the upper limit.

Stacked assemblies: When multiple PCBs stack in a system, the cumulative thickness difference becomes meaningful. Five 1.5mm boards save 0.5mm compared to five 1.6mm boards.

Legacy replacement: Older designs may specify 1.5mm or 0.059″. Matching the original specification ensures drop-in compatibility.

When 0.1mm Doesn’t Matter

For most general electronics applications, the difference between 1.5mm PCB and 1.6mm is functionally irrelevant. If your enclosure has reasonable clearance, your connectors have standard tolerances, and you’re not stacking boards, either thickness works fine.

When to Specify 1.5mm PCB

Based on practical experience, here are scenarios where specifying 1.5mm PCB makes sense:

Matching Existing Specifications

If your design documentation, customer requirements, or legacy system calls for 1.5mm, order 1.5mm. Don’t assume 1.6mm is “close enough” without verifying mechanical compatibility.

European or Japanese Supply Chains

If your product ships to or manufactures in regions that traditionally use 1.5mm specifications, maintaining that specification avoids confusion in documentation and quality control.

Tight Mechanical Tolerances

When your stack-up analysis shows marginal clearance at 1.6mm, specifying 1.5mm provides breathing room without changing your design.

DIY and Prototyping

Many blank copper-clad boards sold for DIY PCB fabrication are labeled 1.5mm. If you’re etching your own boards and want consistency with your purchased materials, design for 1.5mm.

1.5mm PCB Stackup Configurations

Fabricators achieve 1.5mm PCB thickness using standard core and prepreg combinations:

2-Layer 1.5mm PCB Stackup

This straightforward stackup uses a single 1.4mm core with standard 1oz copper on both sides.

4-Layer 1.5mm PCB Stackup

Four-layer boards at 1.5mm require thinner inner copper (0.5oz) and careful prepreg selection to hit the target thickness.

Read more Different PCB Thickness:

0.1mm PCB: The Complete Guide to Ultra-Thin Circuit Boards

0.2mm PCB: Complete Guide to Thin Circuit Board Design & Manufacturing

0.4mm PCB: The Starting Point for Multilayer Circuit Board Design

0.6mm PCB: The First Thickness Supporting All Surface Finishes

0.8mm PCB: Complete Guide to Half-Thickness Board Design & Applications

1.2mm PCB Thickness Guide: Perfect Balance Between Flexibility & Durability

1.5mm PCB: The Often Overlooked Standard Thickness Explained

1.6mm PCB: Why It Became the Industry Standard & Complete Design Guide

1.8mm PCB: The Non-Standard Thickness for Multilayer Board Design

2.0mm PCB: The Heavy-Duty Thickness for Industrial & High-Power Applications

2.4mm PCB: The Ultimate Thick Board Guide for High-Power & Extreme Applications

2.8mm PCB Thickness: When Standard Options Don’t Fit Your Design

3.0mm PCB: Complete Guide for Heavy-Duty Boards Without the 3.2mm Overkill

4.2mm PCB: Custom Backplane Thickness for When 4.0mm Falls Short

4.8mm PCB: Heavy-Duty Backplane Thickness When You Need Nearly 5.0mm Performance

5.6mm PCB: The Ultra-Thick Sweet Spot Between 5.0mm and 6.0mm Backplanes

Applications for 1.5mm PCB

The 1.5mm PCB thickness suits many applications, particularly:

General consumer electronics: Remote controls, simple appliances, and basic electronic devices where standard thickness provides adequate performance.

Educational and hobby projects: The widely available 1.5mm blank copper-clad boards make this thickness natural for DIY PCB fabrication.

Industrial controls: Basic control boards, relay interfaces, and sensor circuits where mechanical robustness matters more than minimum thickness.

Replacement and retrofit boards: Legacy systems originally designed around 1.5mm (or 0.062″ / 1.57mm) specifications.

Cost-sensitive production: When 1.6mm core material costs slightly more in certain regions, 1.5mm offers equivalent performance at potentially lower material cost.

Manufacturing and Ordering Considerations

When ordering 1.5mm PCB, keep these points in mind:

Tolerance Expectations

Standard tolerance for 1.5mm PCB is ±0.1mm (±10%), meaning finished boards may measure 1.4mm to 1.6mm. If you need tighter control, specify this requirement explicitly and expect additional cost.

Communicating with Fabricators

Some fabricators list only 1.6mm in their standard options. If you specifically need 1.5mm:

1. Check if 1.5mm appears in their thickness dropdown or specification table
2. If not, contact them directly to confirm 1.5mm availability
3. Clarify whether “1.6mm” in their system actually produces 1.5mm nominal boards
4. Request the actual stackup documentation to verify target thickness

Material Availability

Most fabricators stock 1.5mm core materials since they’re part of the standard thickness family. However, if you’re working with specialty materials (high-Tg, Rogers, metal-core), verify that the 1.5mm option exists for your specific material choice.

Useful Resources for 1.5mm PCB Design

Thickness and Stackup References:

• Bittele PCB Thickness Options: https://www.7pcb.com/blog/pcb-thickness-options
• Eurocircuits Stackup Information: Detailed buildup configurations
• PCBWay Stackup Library: https://www.pcbway.com/multi-layer-laminated-structure.html

Calculators and Tools:

• Saturn PCB Toolkit (free): Impedance, current capacity, via calculations
• JLCPCB Impedance Calculator: https://jlcpcb.com/impedance

Design Standards:

• IPC-2221B: Generic Standard on Printed Board Design
• IPC-4101E: Specification for Base Materials
• IPC-6012D: Qualification and Performance Specification for Rigid Printed Boards

Material Specifications:

• FR-4 datasheets from Isola, Shengyi, or your preferred laminate supplier
• Core thickness availability charts from your fabricator

Frequently Asked Questions About 1.5mm PCB

Is 1.5mm the same as 1.6mm PCB?

Not exactly, but they’re very close. The 1.5mm PCB is nominally 0.1mm thinner than 1.6mm. However, because both have ±0.1mm tolerance, their actual thickness ranges overlap significantly. A 1.5mm board at the high end of tolerance (1.6mm) equals a 1.6mm board at nominal. For most applications, they’re interchangeable, but if your design has tight mechanical constraints, the distinction matters.

Why do some sources say the standard PCB thickness is 1.5mm while others say 1.6mm?

Both are correct because they’re different roundings of the same original imperial standard (0.062″ or 1/16″). The exact metric conversion is 1.5748mm to 1.5875mm. European and older sources often round down to 1.5mm, while Asian manufacturers typically round up to 1.6mm. The PCB you receive is essentially the same regardless of which label the manufacturer uses.

Can I order 1.5mm PCB from any manufacturer?

Most manufacturers can produce 1.5mm PCB, though not all list it explicitly. Major fabricators like Bittele, JLCPCB, PCBWay, and others either offer 1.5mm as a standard option or can accommodate it as a custom thickness. If you don’t see 1.5mm in the online ordering system, contact the fabricator directly to confirm availability.

Does 1.5mm PCB cost more than 1.6mm?

Generally, no. Both thicknesses fall within the standard range and use commonly available core materials. Pricing typically matches between 1.5mm and 1.6mm options. The exception might be very thin 4-layer or 6-layer boards where hitting exactly 1.5mm requires specific prepreg combinations that could affect cost marginally.

What’s the thickness tolerance for 1.5mm PCB?

Standard tolerance is ±0.1mm, meaning finished boards can measure between 1.4mm and 1.6mm. This approximately ±7% tolerance is typical for boards in this thickness range. Tighter tolerances (±0.05mm) are available but may increase cost and lead time. Always verify tolerance specifications with your fabricator before finalizing mechanical designs that depend on precise thickness.

Conclusion

The 1.5mm PCB occupies a legitimate place in the standard thickness hierarchy, even though it sometimes gets overshadowed by the more commonly cited 1.6mm. Understanding that both measurements derive from the same imperial standard (approximately 1/16″ or 0.062″) helps clarify why different sources cite different numbers for what is essentially the same thickness class.

For most projects, choosing between 1.5mm and 1.6mm comes down to documentation preference and regional conventions rather than technical necessity. However, when mechanical tolerances are tight, when matching legacy specifications, or when working with European supply chains, specifying 1.5mm PCB explicitly ensures you get exactly what your design requires.

The key takeaway: 1.5mm PCB is standard, widely available, and functionally equivalent to 1.6mm for most applications. Don’t let the industry’s inconsistent labeling conventions create unnecessary confusion in your design process.