MANUFACTURING / JAPAN SOURCING

Comparing copper alloys: keep conductivity, strength and temper together

Identify the product form and temper before comparing property values. Check the unit, temperature, test basis and whether each number is typical data, a specification or evidence for the offered lot.

Start with the electrical and mechanical requirements

Imagine choosing copper-alloy strip for a small formed electrical terminal. The buyer needs conductivity and resistance to permanent deformation, but also needs to form the bend without unacceptable damage. Selecting the largest conductivity number in two catalogues does not resolve all three questions.

State the finished part’s electrical, mechanical, forming and service-temperature requirements. Then identify the offered alloy, temper, strip thickness and any later heat or joining operation. Keep tensile strength, proof strength, hardness and stress-relaxation requirements as distinct properties; one number is not a substitute for whichever characteristic the design actually requires.

Read the table headings and notes before joining the numbers

KOBELCO’s SuperKFC page provides a useful reading example.[1] Its physical-property table lists electrical conductivity at 293 K and labels the physical characteristics as typical. The H-temper entry is 85% IACS. The mechanical table lists H tensile strength as 430–530 MPa and says the tensile-strength and hardness entries are standard specifications, with technical specifications determined according to customer requests.

Those entries have different evidential roles. The typical conductivity is not automatically the minimum for every H-temper lot, and the mechanical range is not a test result from the pieces offered to you. Do not combine the strongest value from another temper with the H conductivity as if that pair described one supplied product. Ask which requirements the supplier will commit to for the actual thickness and temper.

Mitsubishi Materials similarly separates representative physical properties from a mechanical-property table organised by temper on its ZC page.[2] Retain the exact product and condition when moving data into your comparison. If the source does not state a condition you need, leave it unresolved and request it rather than filling the gap from a different product.

Keep each property attached to one material condition

1Identify one offer: alloy, temper, form, thickness and source revision
2Read the data: units, temperature, method and typical/specification status
3Confirm the order: agreed requirements and evidence for the supplied lot

This is a data-comparison map, not a strength–conductivity chart. It does not plot a trade-off, rank alloys or assert that separate maximum values can occur together.

Compare the same condition and the right property

For electrical conductivity, retain the stated unit and temperature. Do not mix electrical and thermal conductivity, or treat a resistivity number as a directly comparable conductivity percentage. If a conversion is needed, have its basis and temperature checked rather than copying a number with a new label.

For mechanical properties, request the applicable test basis, specimen direction and supplied condition. For forming, keep bend direction, thickness, radius and the assessment method together. KOBELCO’s bend-formability notes distinguish directions and note thickness dependence.[1] A bend result from one direction or thickness does not settle the terminal drawing in this example.

Compare the evidence for each offered material state
Item	Keep with the catalogue value	Confirm for the actual offer
Material state	Alloy/product, temper, form and data revision	Supplied thickness/size and any processing difference
Conductivity	Electrical unit, temperature and typical/minimum status	Required value, test basis and supplier commitment
Mechanical response	Named property, units, direction and material condition	The design requirement and applicable acceptance evidence
Forming	Direction, thickness, bend geometry and assessment basis	Trial matching the critical feature of the part
Heat and use	Condition at the time of the property measurement	Effect of proposed later operations and evidence needed
Delivery evidence	Source table distinguished from a lot report	Lot identity, reported results and order requirements

Confirm the material before changing the order

Ask the supplier for the offered condition, exceptions to the drawing and the evidence it can provide. If a trial is needed, define the particular question: a bend in the specified direction, a critical dimension after forming, or another required characteristic. Keep the trial decision with that material condition and drawing revision.

A catalogue balance between conductivity and strength helps screen candidates. It does not itself approve an alternative for a terminal, a busbar or a heat-spreader part. Those uses may require different forms, properties and tests. For the terminal example, record who reviews the electrical, mechanical and forming evidence before a change is accepted.

Send HAM the current material requirement, proposed alternative, relevant supplier data, drawing, quantity and destination. Mark the gaps in the comparison so a Japanese supplier can answer them. A missing test condition is a question to resolve, not evidence that the alternative matches.

Questions to send your supplier

Open supplier questions

Part function, drawing revision and destination:
Current material requirement and proposed alloy/product:
Temper, product form, thickness/size and later operations:
Electrical requirement, unit, temperature and test basis:
Mechanical properties actually required, with units and specimen direction:
Forming direction, thickness, critical bend geometry and assessment method:
Service/processing temperatures and evidence for those conditions:
Source document/revision for every quoted value:
Which values are typical, specifications or actual lot results?
Supplier commitments and deviations from the request:
Trial question, acceptance requirements and reviewer:
Lot identity, required report, quantity and open questions:

Save questions ↓

Sources

KOBELCO — SuperKFC copper alloy properties
Read physical-property notes, temper-specific mechanical table and bend-formability notes. Electrical values are typical at 293 K, while tensile/hardness table notes distinguish standard specifications and customer technical specifications. No substitution endorsement.
Mitsubishi Materials — ZC technical data
Read physical-property representative-value heading and mechanical table by 1/2H/H/EH/SH. Reference hardness is separately footnoted. Used to show that alloy identity does not specify the complete comparison state. No numerical ZC values reproduced.