Nickel Alloy Alloy 42-LF (Lead-frame strip)
Additive grade
UNS K94100 · ASTM F30 Alloy 42
Ultra-clean, tight-gauge, low-carbon surface strip specified for semiconductor lead frames and stamped hermetic parts.
Values for the LF condition
Other Alloy 42 tempers and conditions
Alloy 42 is listed in 9 conditions; see the grade overview at Alloy 42.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Rolled + Annealed plate / forged bar | Heavy-section condition for machined fixtures, molds and large glass-to-metal seal bodies. | 250 | 500 | 38 | 140 HB | 2.5 % IACS |
LFThis page Lead-frame strip | Ultra-clean, tight-gauge, low-carbon surface strip specified for semiconductor lead frames and stamped hermetic parts. | 260 | 510 | 38 | 138 HB | 2.5 % IACS |
AnnealedDefault bright/hydrogen annealed strip, sheet and bar (soft) | Default stocked condition: maximum ductility for deep drawing, stamping and glass sealing; stable low expansion. | 270 | 520 | 35 | 145 HB | — |
Strain hardened, half hard | Choose when stamped parts need more stiffness/springback control but still moderate bending ductility. | 480 | 620 | 15 | 10 HRC | 2.5 % IACS |
Cold drawn | Standard bar and wire condition for machined glass-sealing pins, eyelets and headers. | 500 | 640 | 18 | 12 HRC | 2.5 % IACS |
Stress relieved | Pick when stamped or machined parts must hold dimensional stability and flatness after forming, with strength retained. | 560 | 680 | 12 | 13 HRC | 2.5 % IACS |
Strain hardened and partially annealed, half hard | Typical temper for stamped lead frames and shields needing flatness and edge stiffness. | 590 | 700 | 8 | 16 HRC | 2.4 % IACS |
Hardened | Highest strength flat product; use where stiffness dominates and only gentle forming is required. | 720 | 800 | 3 | 22 HRC | 2.4 % IACS |
Spring hard | For contact springs and diaphragms where low expansion must be combined with high elastic limit. | 830 | 900 | 2 | 28 HRC | 2.4 % IACS |
What is Alloy 42-LF?
Alloy 42-LF is Alloy 42 in the LF grade — ultra-clean, tight-gauge, low-carbon surface strip specified for semiconductor lead frames and stamped hermetic parts. Alloy 42-LF has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 84% of nickel alloy grades. Elongation at break is 38% and the elastic modulus is 145 GPa (21 Msi). Alloy 42-LF has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 76% of nickel alloy grades. It melts at 1,425°C (2,597 °F). Annealed is the default condition FabDigit quotes; LF is available on request or by drawing note.
Advantages
- Forms and bends easily — 92/100, better than 99% of nickel alloy grades
- Low embodied carbon — 6.5 kg CO₂/kg, better than 99% of nickel alloy grades
- High electrical conductivity — 2.5 % IACS, better than 85% of nickel alloy grades
Limitations
- Needs corrosion protection — 32/100, worse than 98% of nickel alloy grades
- Low stiffness — 145 GPa (21 Msi), worse than 96% of nickel alloy grades
- Limited service temperature — 400°C (752 °F), worse than 94% of nickel alloy grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of nickel alloy grades
Alloy 42-LF properties
Typical room-temperature values for Alloy 42-LF; 21 are specific to this condition. Other listed values are Alloy 42 reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Alloy 42-LF has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 76% of nickel alloy grades. It melts at 1,425°C (2,597 °F).
Mechanical15
Alloy 42-LF has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 84% of nickel alloy grades. Elongation at break is 38% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
Alloy 42-LF is rated for continuous service to 400°C (752 °F). It conducts heat at 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 73% of nickel alloy grades. Thermal expansion is 4.9 µm/m·K (2.72 µin/in·°F).
Electrical3
Alloy 42-LF conducts electricity at 2.5 % IACS, better than 85% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 98% of nickel alloy grades.
Sustainability4
Producing a kilogram of Alloy 42-LF takes about 85 MJ of energy and emits 6.5 kg of CO₂ — less than 100% of nickel alloy grades. Typical recycled content is 25%.
Manufacturability7
Alloy 42-LF's machinability is poor (28/100, better than 82% of nickel alloy grades); weldability very good (72/100); formability excellent (92/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Alloy 42-LF
Is Alloy 42 easy to machine?
Gummy and work-hardening like austenitic stainless — use sharp positive-rake carbide, rigid setups, heavy positive feeds, and flood coolant; avoid dwelling.
Can Alloy 42 be welded?
Readily GTAW, EB, laser and resistance welded with matching Alloy 42 filler; keep joints free of carbon, sulphur and oil to preserve expansion behaviour and avoid hot cracking.
Can Alloy 42 be formed, bent or molded?
Excellent deep-drawing and stamping response in the annealed temper; interstage anneal at 800–900 °C in dry hydrogen for heavy reductions.
What surface finishes work on Alloy 42?
Not anodizable — glass-sealing parts are wet-hydrogen decarburised/oxidised, then Ni, Ag, Sn or Au plated for solderability and corrosion protection.
Alloy 42 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| NiGB 4J42 narrows to 41.5–42.5 | 40.5 – 43.5 | 42 |
| C | ≤ 0.05 | 0.03 |
| Mn | ≤ 0.8 | 0.4 |
| Si | ≤ 0.3 | 0.15 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cr | ≤ 0.25 | — |
| Co | ≤ 0.5 | — |
| Aldeoxidiser residual | ≤ 0.1 | — |
| Mgdeoxidiser residual | ≤ 0.1 | — |
| Ti | ≤ 0.1 | — |
| Cu | ≤ 0.2 | — |
| Febalance, ≈57–58% | balance | — |
Alloy 42-LF — frequently asked
What is Alloy 42-LF used for?
Alloy 42-LF is typically used for IC lead frames, glass-to-metal seals, TO-can transistor packages and electronic component leads. In short: standard lead-frame alloy; matched to silicon and borosilicate; excellent deep-drawing strip.
What is the yield strength of Alloy 42-LF?
Alloy 42-LF has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 84% of nickel alloy grades. Strength varies by condition: see the 9 listed tempers.
Is Alloy 42-LF easy to machine?
Not especially — machinability is rated poor (28/100, better than 82% of nickel alloy grades). Gummy and work-hardening like austenitic stainless — use sharp positive-rake carbide, rigid setups, heavy positive feeds, and flood coolant; avoid dwelling.
Can Alloy 42-LF be welded?
Yes — weldability is rated very good (72/100). Readily GTAW, EB, laser and resistance welded with matching Alloy 42 filler; keep joints free of carbon, sulphur and oil to preserve expansion behaviour and avoid hot cracking.
What surface finishes work on Alloy 42-LF?
Not anodizable — glass-sealing parts are wet-hydrogen decarburised/oxidised, then Ni, Ag, Sn or Au plated for solderability and corrosion protection.
Can Alloy 42-LF be formed, bent or molded?
Excellent deep-drawing and stamping response in the annealed temper; interstage anneal at 800–900 °C in dry hydrogen for heavy reductions.
What is the maximum service temperature of Alloy 42-LF?
Alloy 42-LF is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Alloy 42 Annealed and Alloy 42 Spring?
Annealed is the default condition — default stocked condition: maximum ductility for deep drawing, stamping and glass sealing; stable low expansion. Spring: for contact springs and diaphragms where low expansion must be combined with high elastic limit. Yield strength is 270 MPa in Annealed versus 830 MPa in Spring.
Sources
- ASTM F30 — Standard Specification for Iron-Nickel Sealing Alloys — ASTM International (2018)
- GB/T 15018 / YB/T 5241 — 4J42 (2019)
- Alloy 42 (UNS K94100) controlled-expansion alloy datasheet — Carpenter Technology / Ed Fagan (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Low-Expansion Alloys) — ASM International (1990)
- ASM Specialty Handbook: Nickel, Cobalt and Their Alloys — ASM International (2000)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.