MATERIAL COMPARISON
Compare the composition and construction, not just the abbreviation.
A useful comparison starts with the actual product offered. Keep the material designation, copper proportion and component construction together rather than treating MoCu or WCu as a complete specification.
Comparison table
On a narrow screen, scroll the table sideways. Keyboard: focus the table and use the arrow keys.
| Criterion | MoCu | WCu |
|---|---|---|
| Constituents | Molybdenum and copper. | Tungsten and copper. |
| Thermal-management route | Spectra-Mat describes MoCu heat spreaders and semiconductor packaging. | Spectra-Mat describes WCu thermal bases and heat sinks. Neither family name fixes the expansion or conductivity. |
| Electrical-contact context | The thermal-management reference does not qualify a MoCu product for switching or arc duty. | MTS identifies arc-contact and EDM-electrode applications for WCu; qualify the particular grade and duty. |
| Construction | Identify a bulk composite separately from a layered product such as Cu/MoCu/Cu. | Identify the composite grade, copper proportion and any coatings or joining layers. |
| Values needed for a defensible comparison | Obtain product-specific thermal conductivity, W/(m·K); expansion coefficient, 10⁻⁶/K; and density, g/cm³. | Use the same measurement temperature, expansion interval and direction. Do not transfer pure-W density to WCu. |
Scope of the comparison
This table is qualitative. No property numbers are taken from the Spectra-Mat page’s provisional specification section. A matched numerical ranking requires validated data for the actual composition, product form and delivered condition; a laminate is not the same material construction as a bulk composite.
Selection conditions
- For a heat spreader, compare expansion compatibility with the mating substrate and thermal resistance of the complete joint, not only a conductivity headline.
- For a switching contact or electrode, evaluate erosion, electrical duty and the actual grade separately; a thermal-management designation is not an electrical-contact approval.
- When mass or geometry is constrained, compare the finished component using the density of the quoted composite. Replacing MoCu with WCu or the reverse still requires design approval.
Sources for this table
Spectra-Mat: MoCu and WCu applications (English; qualitative use only)Midwest Tungsten Service: WCu applications (English)References reviewed on 14 September 2026. Manufacturer references identify their own materials, not an MNK stock item or a supplier partnership.
What do the manufacturer references establish?
Plansee describes MoCu30 as a molybdenum-copper composite and PMC141 as a Cu/MoCu30/Cu laminate. Its W-MMC brochure separately identifies tungsten-copper composites.
Plansee materials: MoCu30 and PMC141 (English)
Plansee W-MMC brochure, September 2021 (English PDF)
Composition
Ask what each percentage means and which product it describes. Do not compare a family name against a fully specified grade as if the offers were identical.
Construction
Keep a layered product separate from a bulk-composite offer. Include the arrangement and thickness of layers where the drawing requires them.
Property evidence
Compare thermal or electrical data only when the supplier identifies the product, measurement direction and temperature basis. A single headline value is not an acceptance decision.
How to make the offers comparable
- Identify whether the request concerns a blank, a layered part or a finished component.
- Keep the same geometry and quantity in both requests.
- Ask the supplier to identify the composition and construction behind the quoted designation.
- Assess any proposed alternative against the component requirements, including the intended joining arrangement; obtain design approval before substitution.
No universal winner, guaranteed conductivity, expansion value, density or price advantage is asserted. This guide does not qualify a composite for a specific assembly.
Continue with the material pages
Source reviewed: 14 September 2026. Original procurement guidance by MNK-G.S.A.