Heavy and Extreme Copper PCBs for Military/Aerospace Applications

Manufacturing That Eliminates Risk & Improves Reliability

Heavy and Extreme Copper PCBs for Military/Aerospace Applications

Engaging For Reliability

10.27.16

Manufacturing That Eliminates Risk & Improves Reliability2

Overview

Standard commercial PCBs are typically built to perform for a relatively short time, in relatively controlled environments.

PCBs for military and aerospace applications must operate for years, while exposed to extremes of temperature, altitude, and vibration.

Maximum reliability is essential. Epec has experience building heavy and extreme copper PCBs for a variety of critical high-power applications, from nuclear submarines to drone aircraft.


Agenda

Categories of PCB by Copper Weight

Heavy Copper Fabrication Techniques

Epec built PCBs Showing Various of Advantages of Heavy Copper

Overall Cost vs. Reliability

Getting a Quote:– Process, Adders, Expectations

Planning

Additional Resources


Defining The PCB Type

Standard Copper: Entire layer 1/4 oz/ft2 to 4 oz/ft2

Heavy Copper (HC): Entire layer 5 oz/ft2 up to 19 oz/ft2.

EXTREME Copper (XC): Entire layer 20 oz/ft2 up to 200 oz/ft2

PowerLink (PL): 2 or more copper weights, generally standard copper plus either heavy or extreme copper, on the same external layer.


Heavy Copper Fabrication Techniques

Additive (Plating)

– Pro• Well defined trace edge• Finer Traces/Spaces possible

– Con• More Expensive• May Require Machining

Subtractive (Etching)

– Pro• Etching costs less than plating

– Con• Trace Less Well Defined• Cross Section- Trapezoid• Requires Larger Traces/Spaces


PowerLink(Multiple Copper Weights On A Single Layer)

Different areas plated to different weights.

Combine power section with logic.

Typically used on external layers.

Lighter copper areas permit component soldering, and higher density devices.

Multiple stage additive process.


Advantage: Mechanical Durability

The heavy copper planes add to the overall mechanical strength of the XCPCB.

Mechanical vias with extra plating used here to reinforce the Z Axis.


Advantage: Reduced Layer Count

This PLPCB uses just a few 6-oz copper traces (red) on the top and bottom layers, with a 1-oz surface mount control section.

An earlier version formed these connections by using parallel 3-oz internal signal layers, top and bottom. The result was an 8-layer PCB.

Instead, it is kept to just 4 layers, with superior cooling of 6-oz traces in air.


Advantage: Package Size Reduction

This PowerLink PCB combines a 2-oz control section with a 12-oz power section on different areas of the same surface.

The heavy copper replaced additional wiring, cutting down on assembly.

Heavy copper can also eliminate the need for bus bars -- another savings in assembly time and package size, with increased long-term reliability.


Advantage: Simplified Assembly

Here is a very small HCPCB which attaches to a larger one. It must stand away from the mating surface on raised pedestals. For the proof of concept prototype, the tiny pedestals were pre-machined, then added individually.

The manual step would have been prohibitively time-consuming and costly in volume. Epec replaced the pedestals with .016”-high copper plated pads. Assembly is simplified, and the better-bonded pads offer superior reliability.


Advantage: Extreme Trace Thickness

This XCPCB uses 120-ounce (.144”) copper internal traces. These are pre-machined and embedded into the internal layer structure.

The terminals are then plated up several additional ounces above the surface.

The remaining external layer is 2-oz copper, for SMT component assembly.


Costs vs. Reliability

Heavy copper PCBs do require extra processing and materials that add cost.

Costs include long plating cycles, multiple film resist applications, and multiple soldermask coats. Multilayers typically require extra plies of pre-preg.

These costs must be weighed against the previously listed advantages of heavy copper, including long term reliability. Epec will work with you to quote your project so that you can weigh your options.


Quote Cycle Turnaround Time

Every heavy / extreme copper quote requires a full design review.

This is because each design is to some extent unique, and does not lend itself to “checklist” style pricing.

Some orders require purchase of at least some custom materials for which we need to check availability.

Most quotes require some discussionso that all requirements are captured.

The quote cycle can therefore takefrom a few days to a week or more.


Heavy Copper Cost Factors

Some Cost Factors:– For small-run prototypes, custom materials may be subject to minimum order

quantity pricing.– Heavy copper PCBs often require special processing and equipment.– Plating, imaging, etching, and lamination cycles are often quite long, and consume

more materials than usual.– Because of these factors, Epec is not able to offer quick turn build cycles.– Most orders will require a minimum of 20-25 working days to produce, not including

ordering time for special materials.


Engage In The Epec Quote Process

Question: What can you, as the customer, do to get your quote in a timely fashion?

– Ask Epec for recommendations, early in the cycle, about optimizing your design choices.

– The more advanced your documentation, the faster we can quote. In particular, even a basic concept drawing is extremely valuable.

– Let us know your expectedquantities for both prototype andproduction. In production volume,factors like larger material buys cansignificantly reduce pricing.


Plan Ahead, Budget Time

Plan your project as far in advance as possible, and start production as soon as is practical. Heavy copper PCBs require extra time to process, and there is no way to “rush” the production cycle to make up for a delayed release.

Understand that these PCBs have cost structures that are, to varying degrees, significantly higher than standard PCBs. They are not suitable for every application. They can, however, be the best solution when reliability is critical.


Resources: Design Help

Epec can supply heavy copper resources you can use in your design cycle.

Trace width and spacing guides.

Current carrying charts.

Advice on best options and best practices.


Summary

Epec’s heavy and extreme copper PCBs offer reliability in critical military and aerospace applications.

We can offer solutions that are manufacturable and repeatable, based on our experience with a wide variety of applications.

We encourage you to engage with Epec early in your project to discuss options for a successful experience.


Our Products

Battery Packs Flex & Rigid-Flex PCB’s User Interfaces

Fans & Motors Cable Assemblies Printed Circuit Boards


Design Centers & Technical Support

Battery Pack & Power Management – Denver, CO User Interfaces – Largo, FL Fans & Motors – New Bedford, MA & Wales, UK PCB’s – New Bedford, MA & Shenzhen, China Flex & Rigid Flex – Toronto, Canada Cable Assemblies – Largo, FL

Our Engineering and Design teams are ready to help our customers create world class and cost effective product solutions.


Q&A

Questions?– Enter any questions you may have

in the Control Panel

– If we don’t have time to get to it, wewill reply via email


Thank YouCheck out our previous webinars at www.epectec.com.

For more information email [email protected].

Stay Connected with Epec Engineered TechnologiesFollow us on our social media sites for continuous technical updates and information:

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Heavy and Extreme Copper PCBs for Military/Aerospace Applications

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