Wedgelock Finish Options and How to Choose the Right One

VPX wedgelock and hardware finishes rarely get the same attention as thermal performance or mechanical retention, yet the wrong finish can cause corrosion, wear failure, or a compliance rejection. Engineers specifying SOLIDWEDGE™ wedgelocks and related assembly hardware need to weigh corrosion resistance, insertion/extraction durability, thermal and electrical performance, lubricity, and RoHS/REACH/DFARS compliance all at once. This guide breaks down the finish and plating options available for VPX wedgelock hardware and when each one makes sense.

What Finish Options Are Available for VPX Wedgelock Hardware?

VPX wedgelock and assembly hardware typically ship in one of eight finishes, split between a standard fastener material and a set of aluminum plating options. Each finish has a governing military or AMS specification, a RoHS/REACH/DFARS compliance profile, and a use case it fits best.

What Is the Standard Fastener Material for VPX Wedgelock Hardware?

Screws, nuts, washers, and SOLIDWEDGE™ straps are typically made from 300 series stainless steel, passivated per AMS-2700. This material meets DFARS, RoHS, and REACH requirements and gives the mechanical fastening hardware corrosion resistance that matches the service life of the wedgelock itself.

What's the Difference Between Black Anodized and Black Anodized Hardened Finishes?

Black Anodized (BA) is finished per MIL-A-8625 Type II Class 2. It provides reliable corrosion resistance and durability, and it holds up well in applications with high insertion/extraction counts.

Black Anodized Hardened (BH) steps up to MIL-A-8625 Type III Class 2, a hardcoat anodize process. BH provides superior corrosion resistance and higher durability than standard BA, making it the better choice for the harshest rugged environments where hardware sees repeated mating cycles over the life of the system.

If the application involves shock, vibration, and frequent module servicing, BH is generally the safer default. Standard BA remains a solid option for applications with less demanding cycle life requirements.

Which Finish Offers the Best Thermal and Electrical Performance?

Electroless Nickel (EN), finished per MIL-C-26074 Class 4 Grade B, delivers excellent thermal performance alongside excellent electrical conductivity. For wedgelock hardware where the thermal path and the electrical bond both matter, EN is the standard high-performance choice.

When Do Specialty Finishes Like HXN and BHT Make Sense?

Electroless Nickel Hex Boron Nitride (HXN) and Black Anodized Hardened with Teflon (BHT) add a lubricious topcoat on top of EN and BH. They're specialty finishes, not standard options, reserved for the rare, highest-performance applications where that added lubricity is worth it. Less friction means less wear over repeated insertion/extraction cycles, which helps the wedgelock hold its clamping force more consistently over the life of the hardware. For most VPX designs, standard EN or BH already meets the requirement.

Both cost more and take longer to source than BA, BH, or EN, and both are available on select SOLIDWEDGE™ models rather than the full product line. Confirm availability and lead time with WaveTherm engineering before specifying either one for a new design.

How Do I Choose the Right Finish for a VPX Wedgelock Application?

A practical way to narrow the decision is to start with the dominant requirement for the application.

• General ruggedized use: Black Anodized (BA) covers most standard corrosion resistance and durability needs.
• Harsh environments, moderate cycle count: Black Anodized Hardened (BH) for superior corrosion resistance and durability over standard BA.
• Rare, highest-performance environments with an especially high insertion/extraction count: Black Anodized Hardened with Teflon (BHT), a specialty option worth the added cost and lead time only when plain BH genuinely isn't enough.
• High-performance thermal and electrical requirements: Electroless Nickel (EN) is the standard choice. Electroless Nickel Hex Boron Nitride (HXN) is a specialty option reserved for the rare cases that also need added lubricity.
• Legacy program requirements: Chemical Film Clear (CC) or Chemical Film Gold (CG), only when a customer spec calls for it, and never CG on a RoHS or REACH restricted program.

What Are the Limitations of Chemical Film Clear and Chemical Film Gold Finishes?

Chemical Film Clear (CC) and Chemical Film Gold (CG) are conversion coatings finished per MIL-DTL-5541. Both provide decent electrical conductivity, but both are soft finishes with lower durability, and neither holds up well under high insertion/extraction counts.

Chemical Film Gold carries an added compliance concern. It fails both RoHS and REACH, which rules it out for programs with environmental compliance requirements.

WaveTherm does not offer CC or CG across all wedgelock models, and generally discourages both for new designs. These finishes still show up in specific programs, usually where a customer needs to match a legacy baseline or an existing contract spec. Outside of that narrow case, Black Anodized or Black Anodized Hardened is almost always the better choice for a comparable application.

Building Finish Selection Into Your VPX Design

Finish selection is one more variable to weigh alongside clamping force, thermal contact area, and mechanical retention when specifying wedgelock hardware for a VPX system. An incorrect finish choice can lead to corrosion, premature wear, or a failed compliance review after the design is already locked in.

WaveTherm's SOLIDWEDGE™ wedgelocks are available across this finish range, so engineers can match the plating to the mission requirement without compromising on the positive retraction and thermal performance SOLIDWEDGE™ wedgelocks are built around.