0.9mm PCB: Custom Thickness Guide for Non-Standard Board Requirements

If you’ve been searching for information on 0.9mm PCB thickness, you’ve probably noticed something: it’s not listed in most manufacturers’ standard options. That’s not a mistake—0.9mm falls between the common 0.8mm and 1.0mm thicknesses, making it a custom specification that requires special ordering.

I’ve worked with engineers who needed precisely 0.9mm boards for enclosure fit requirements or legacy product compatibility. While it takes extra planning, getting a custom 0.9mm PCB manufactured is absolutely possible. This guide explains when non-standard thickness makes sense, how manufacturers create custom boards, and what you need to know before placing an order.

Why 0.9mm PCB Is Not a Standard Thickness

Let me be direct: 0.9mm PCB is not a standard thickness option at most fabrication houses. When you look at manufacturer catalogs, you’ll see offerings like 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, and 1.6mm—but rarely 0.9mm.

Why is this? Standard thicknesses evolved from commonly available core materials that manufacturers stock in bulk. These materials come in specific dimensions that allow efficient production. When you order a standard thickness, the fabricator likely has the exact core material ready to go.

Standard vs Non-Standard PCB Thickness Options

Here’s how 0.9mm compares to what manufacturers typically offer:

The gap between 0.8mm and 1.0mm exists because most applications fit comfortably into one of these two standard options. However, certain situations genuinely require something in between.

When Does a 0.9mm PCB Make Sense?

You might be wondering: why not just use 0.8mm or 1.0mm instead? Fair question. Here are legitimate scenarios where specifying 0.9mm PCB thickness is justified:

Enclosure Compatibility Requirements

The most common reason for non-standard thickness is enclosure fit. If you’re designing a replacement board for an existing product—or your mechanical engineer has already finalized an enclosure with tight tolerances—you may need exactly 0.9mm to fit properly. A 0.1mm difference might seem trivial, but in card-edge connectors or slot-mounted boards, it matters.

Legacy Product Replacement

When replacing boards in older equipment, you sometimes encounter non-standard dimensions that were common decades ago. Rather than redesigning the entire mechanical assembly, ordering a custom thickness board is often more practical.

Impedance Control Requirements

In RF and high-speed digital designs, the dielectric thickness between signal layers and reference planes directly affects trace impedance. Sometimes the math works out to require a specific overall thickness that doesn’t match standard options. A 0.9mm PCB might be the result of impedance calculations that don’t align with 0.8mm or 1.0mm stackups.

Connector Specifications

Certain board-to-board connectors and card-edge interfaces specify exact PCB thickness tolerances. If your connector datasheet calls for 0.85mm-0.95mm board thickness, a 0.9mm target makes more sense than hoping your 1.0mm board comes in at the low end of tolerance.

How Manufacturers Create Custom 0.9mm PCB Thickness

Understanding how fabricators achieve non-standard thicknesses helps you communicate effectively when ordering. Here’s what happens behind the scenes:

The Building Blocks of PCB Thickness

Every PCB is constructed from layers of material stacked together:

To achieve a specific total thickness like 0.9mm, the manufacturer selects core and prepreg combinations that add up correctly. For a 2-layer 0.9mm PCB, they might use:

• 0.8mm core
• 0.035mm copper (1oz) × 2 sides = 0.070mm
• Solder mask and finish ≈ 0.030mm
• Total: ~0.9mm

For multilayer boards, the math gets more complex, combining multiple thin cores with prepreg layers.

Custom Stackup Process

When you order a non-standard thickness, the manufacturer’s engineering team:

1. Reviews your thickness requirement against available materials
2. Calculates a stackup using available cores and prepregs
3. Verifies the combination meets your other specs (impedance, layer count)
4. May request approval of the proposed stackup before production

This engineering review adds time to your order but ensures the board meets specifications.

0.9mm PCB vs Standard Alternatives: Which Should You Choose?

Before committing to custom thickness, honestly evaluate whether 0.8mm or 1.0mm could work. Here’s a practical comparison:

My recommendation: If your mechanical tolerance allows ±0.1mm, seriously consider using 0.8mm or 1.0mm instead. You’ll save money, reduce lead time, and have more supplier options. Reserve custom 0.9mm PCB for situations where the exact thickness is genuinely non-negotiable.

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

How to Order Custom Thickness PCBs

If you’ve determined that 0.9mm is truly necessary, here’s how to proceed:

Step 1: Verify Manufacturer Capability

Not all fabricators accept custom thickness orders. Before investing design time, confirm your chosen manufacturer can accommodate 0.9mm. Look for:

• “Custom thickness” option in their online quote system
• Thickness specification in 0.01mm increments (not just dropdown selections)
• Explicit statement of custom stackup capability

Some manufacturers like MacroFab, PCBWay, and JLCPCB offer thickness specification from 0.2mm to 6.3mm in fine increments.

Step 2: Specify Clearly in Your Documentation

Include the thickness requirement in multiple places:

• Fabrication drawing (mandatory)
• Gerber file notes
• Online order form
• Email communication with sales rep

State both the target (0.9mm) and acceptable tolerance (typically ±10%, so 0.81mm to 0.99mm).

Step 3: Request Stackup Confirmation

Before production begins, ask for a proposed stackup document showing:

• Core thickness(es)
• Prepreg type and count
• Copper weights per layer
• Calculated total thickness

Review this carefully—once production starts, changes are expensive.

Step 4: Expect Longer Lead Times

Custom thickness orders typically add:

• 1-2 days for engineering review
• 1-3 days for material procurement (if not in stock)
• Standard production time

Plan for 5-7 additional days compared to standard thickness orders.

Cost Implications of Non-Standard Thickness

Let’s talk money. Custom 0.9mm PCB orders cost more than standard thickness for several reasons:

Why Custom Thickness Costs More

Typical Cost Premium

Based on my experience, expect:

• Prototype quantities (5-20 pcs): 15-25% premium
• Small production (50-500 pcs): 10-15% premium
• Volume production (1000+ pcs): 5-10% premium (materials can be stocked)

The percentage decreases with volume because material costs become a smaller portion of the total, and manufacturers can justify stocking your specific materials.

Design Tips for 0.9mm PCB Projects

If you’re proceeding with a 0.9mm design, keep these practical tips in mind:

Tip 1: Design for Tolerance

The ±10% thickness tolerance on a 0.9mm board means you could receive boards from 0.81mm to 0.99mm. Design your mechanical interfaces (connectors, enclosures) to accommodate this range.

Tip 2: Limit Layer Count

Achieving exactly 0.9mm becomes increasingly difficult as layer count increases. For 2-layer boards, it’s straightforward. For 4-layer boards, it’s manageable. Beyond 4 layers at 0.9mm, you’re severely constraining the stackup options.

Tip 3: Communicate Early with Your Manufacturer

Don’t wait until you’ve finalized your design to discuss custom thickness. Reach out early, share your requirements, and get their recommended stackup before you start layout.

Tip 4: Consider Prototyping at Standard Thickness First

If your design allows, prototype at 0.8mm or 1.0mm to validate electrical functionality. Then switch to 0.9mm for production runs once you’ve confirmed the design works. This saves money during the iteration phase.

Useful Resources for Custom PCB Thickness Orders

Here are tools and references for working with non-standard thicknesses:

Online Stackup Calculators

• Saturn PCB Toolkit – Free Windows app for stackup and impedance calculations
• JLCPCB Impedance Calculator – Shows available stackup options
• Sierra Circuits Stackup Planner – Interactive multilayer planning

Manufacturer Custom Thickness Services

• MacroFab – 0.2mm to 6.3mm in 0.01mm increments
• PCBWay – Custom stackup service with engineering support
• Advanced Circuits – Dedicated custom thickness program

Design Standards

• IPC-2221B – Generic Standard on Printed Board Design
• IPC-6012E – Qualification and Performance Specification for Rigid PCBs

Frequently Asked Questions About 0.9mm PCB

Can I order 0.9mm PCB from any manufacturer?

Not all manufacturers accept custom thickness orders. Budget fabricators focusing on quick-turn standard boards may not accommodate 0.9mm. Look for manufacturers that explicitly offer custom stackup services or thickness specification in fine increments. Expect to pay a premium compared to standard thickness options, and plan for additional lead time for engineering review and potential material procurement.

What is the thickness tolerance for 0.9mm PCB?

Industry-standard thickness tolerance is ±10% per IPC-6012 specifications. For a 0.9mm PCB, this means your boards could measure anywhere from 0.81mm to 0.99mm and still be within specification. If your application requires tighter tolerance, discuss this with your manufacturer—tighter specs are possible but add cost and may require 100% thickness verification.

How many layers can I have in a 0.9mm PCB?

For a 0.9mm total thickness, 2-layer and 4-layer configurations are practical. Six layers at 0.9mm is theoretically possible but severely limits your dielectric thickness options, potentially compromising impedance control and signal integrity. If you need more than 4 layers, consider whether 1.0mm or 1.2mm thickness could work for your application instead.

Is 0.9mm PCB more expensive than 0.8mm or 1.0mm?

Yes. Custom 0.9mm PCB typically costs 10-25% more than standard 0.8mm or 1.0mm boards. The premium comes from engineering review time, potential material procurement delays, and inability to panelize with other customer orders. The cost difference decreases with higher volumes but never fully disappears.

Why would I choose 0.9mm instead of a standard thickness?

The main reasons to specify 0.9mm are: exact enclosure fit requirements where 0.8mm is too thin and 1.0mm is too thick; legacy product replacement where the original used non-standard dimensions; specific connector requirements with tight thickness tolerances; or impedance calculations that don’t align with standard stackups. If none of these apply, using 0.8mm or 1.0mm will save time and money.

Conclusion

Ordering a 0.9mm PCB is absolutely possible, but it requires understanding that you’re requesting a custom specification. Unlike standard thicknesses that manufacturers produce routinely, 0.9mm falls in a gap that requires special engineering attention and potentially non-stock materials.

Before committing to this non-standard thickness, honestly evaluate whether 0.8mm or 1.0mm could meet your requirements. If the answer is no—due to enclosure constraints, connector specs, or legacy compatibility—then proceed with custom ordering, but budget extra time and money accordingly.

The key to success with custom thickness boards is communication. Discuss your requirements with your manufacturer early, request stackup confirmation before production, and design your mechanical interfaces to accommodate the standard ±10% thickness tolerance.

When you genuinely need exactly 0.9mm, it’s achievable. Just go in with realistic expectations about cost, lead time, and the ordering process.