A DO-41 package body measures 4.10 mm to 5.20 mm long and 2.00 mm to 2.70 mm in diameter, with 0.71 mm to 0.86 mm leads at least 25.4 mm long on each end. For a footprint that accepts any manufacturer’s part, drill 1.1 mm, use a 1.5 mm pad, and set horizontal pitch at 10.16 mm. Here is where each of those numbers comes from, and where the datasheets disagree.

Key takeaways

• Body 4.10 mm to 5.20 mm × 2.00 mm to 2.70 mm; leads 0.71 mm to 0.86 mm diameter, 25.40 mm minimum length. Vishay, onsemi and Diodes agree within 0.004 mm; MCC’s drawing allows 0.90 mm leads.
• Drill 1.1 mm for IPC-2222 Level B against a 0.90 mm worst-case lead. Pad 1.5 mm gives the Level B annular ring and fabrication allowance.
• Use 10.16 mm horizontal pitch, not 7.62 mm. At 7.62 mm the lead bend falls inside the 1.27 mm zone where onsemi does not control lead diameter.
• Thermal resistance is a mounting spec, not a package spec: the same 1N4001 is quoted at 50 °C/W, 87 °C/W or 100 K/W depending on lead length, copper area and whose datasheet you opened.
• The package answers to four names: DO-41, DO-204AL, SOD66 and SOD81. Search distributors on DO-204AL.
• Lifecycle is moving. onsemi has discontinued its non-Pb-free 1N400x parts, and Diodes has pushed the series toward S1A–S1M in SMA.

[IMAGE 1: Macro photograph of a 1N4007 in DO-41 beside a caliper reading the 2.7 mm body diameter, with the cathode band and lead-to-body transition visible | alt: “DO-41 package axial diode with cathode band, body diameter measured at 2.7 mm”]

What the DO-41 package is

DO-41 is a JEDEC axial-lead through-hole outline for rectifier diodes, registered as DO-204AL. The body is a moulded plastic or glass cylinder up to 5.20 mm long and 2.70 mm in diameter, with a round lead at each end and a painted band marking the cathode. The canonical part is the 1N4001 to 1N4007 series at 1.0 A.

The naming is messier than it looks, and it costs people library matches. Wikipedia and NXP pair DO-41 with SOD66. The official KiCad through-hole diode library names every one of its footprints D_DO-41_SOD81_*, using SOD81 instead. An older Vishay Semiconductor GmbH drawing, document 84026 rev. 1.1 dated 29-Jan-04, labels a DO-41 plastic body DO-204AM, while Vishay General Semiconductor’s current 1N4001 datasheet, document 88503 rev. 29-Apr-2020, says DO-41 (DO-204AL).

Practical rule: search parametric tools on DO-204AL. That is the string DigiKey’s filter uses, rendered as “DO-204AL, DO-41, Axial”. If a search on DO-41 alone comes back thin, that is why.

DO-41 dimensions

Three manufacturers, three drawings, one package. Values below are read from the current package files, not from a secondary source.

Dimension	Vishay 88503 (rev. 29-Apr-2020)	onsemi Case 59-10 (issue U)	Diodes DO-41 Plastic (rev. 2017-05-15)	MCC M-DO-41-A (rev. 5)
Body length	4.1 mm to 5.2 mm	4.10 mm to 5.20 mm (A)	4.06 mm to 5.21 mm (B)	4.10 mm to 5.20 mm (G)
Body diameter	2.0 mm to 2.7 mm	2.00 mm to 2.70 mm (B)	2.00 mm to 2.72 mm (D)	2.00 mm to 2.70 mm (Ød)
Lead diameter	0.71 mm to 0.86 mm	0.71 mm to 0.86 mm (D)	0.71 mm to 0.864 mm (C)	0.70 mm to 0.90 mm (Øb)
Lead length, each end	25.4 mm min.	25.40 mm min. (K)	25.40 mm min. (A)	25.4 mm min. (L)
Uncontrolled lead zone	not stated	1.27 mm max. (F)	not stated	not stated
Approximate weight	0.33 g	0.4 g	0.340 g	not stated

Two details in that table matter more than the rest. MCC’s drawing permits a 0.90 mm lead, 0.04 mm fatter than everyone else’s; if your board has to accept any DO-41 on the market, size the hole from 0.90 mm. And onsemi’s note 5 states that lead diameter is not controlled within dimension F, 1.27 mm from the body. That zone decides your pitch, as the next section shows.

Vishay’s outline carries a second lead diameter, 0.58 mm to 0.66 mm, annotated as applying to suffix “E” part numbers. Confirm which lead your ordered part number actually carries before you fix the drill; a hole sized for the thin lead will not take a standard one.

The DO-41 footprint: hole, pad and pitch

IPC-2222 sets the hole from the maximum lead diameter plus an allowance that depends on density level: 0.25 mm for Level A, 0.20 mm for Level B, 0.15 mm for Level C. IPC-2221 then sets the land as hole size plus twice the minimum annular ring (0.05 mm) plus a fabrication allowance of 0.40 mm, 0.25 mm or 0.20 mm for the same three levels.

Run that against the 0.90 mm worst-case lead and the 0.86 mm single-source lead:

Density level	Hole, 0.90 mm lead	Pad, 0.90 mm lead	Hole, 0.86 mm lead	Pad, 0.86 mm lead
A (general)	1.15 mm → drill 1.2 mm	1.65 mm → 1.7 mm	1.11 mm → drill 1.2 mm	1.61 mm → 1.6 mm
B (standard)	1.10 mm → drill 1.1 mm	1.45 mm → 1.5 mm	1.06 mm → drill 1.1 mm	1.41 mm → 1.5 mm
C (high density)	1.05 mm → drill 1.1 mm	1.35 mm → 1.4 mm	1.01 mm → drill 1.0 mm	1.31 mm → 1.4 mm

Level B at a 1.1 mm drill and a 1.5 mm pad is the sensible default. It clears the fattest lead any manufacturer ships, survives wave and selective soldering, and still leaves room for rework.

Pitch is where most DO-41 footprints go wrong. The body runs to 5.20 mm, so a horizontal pitch P leaves (P − 5.20) / 2 of lead per side before the bend. At the 7.62 mm pitch offered in the KiCad library, that is 1.21 mm, which sits inside onsemi’s 1.27 mm uncontrolled zone and close enough to the body to stress the lead-to-body seal. At 10.16 mm you get 2.48 mm per side, clearing the uncontrolled zone with 1.21 mm of controlled lead to bend against.

Pitch	Orientation	Free lead per side	Use it when
7.62 mm	Horizontal	1.21 mm	Avoid. The bend lands in the uncontrolled-diameter zone
10.16 mm	Horizontal	2.48 mm	Default choice for DO-41
12.70 mm	Horizontal	3.75 mm	Strain relief, hand assembly, or extra pad-to-pad spacing at high voltage
5.08 mm	Vertical	one lead bent 180°	Board area is tight and the diode dissipates little
3.81 mm / 2.54 mm	Vertical	very tight bend radius	Only with pre-formed leads

At 10.16 mm pitch with 1.5 mm pads you have roughly 8.7 mm of bare laminate between pad edges. A 1N4007 blocks 1000 V, so on a mains-referenced board that gap, not the package, is what your creepage and clearance analysis works with. Diodes’ package file flags the same point and defers to sector guidelines.

[INTERNAL LINK: through-hole land patterns -> IPC-2221 and IPC-2222 hole and pad sizing]

[IMAGE 2: Dimensioned land-pattern drawing for a horizontal DO-41 at 10.16 mm pitch showing 1.1 mm holes, 1.5 mm pads, body outline and the 1.27 mm uncontrolled lead zone shaded | alt: “DO-41 package footprint with 1.1 mm holes, 1.5 mm pads and 10.16 mm pitch”]

Thermal: the same diode is 50 °C/W or 100 K/W

A DO-41 diode dumps its heat out through its leads into the board. That makes junction-to-ambient thermal resistance a property of your layout, and the datasheets say so in wildly different ways.

Source	RθJA	Stated conditions
Vishay 88503	50 °C/W (RθJL 25 °C/W)	0.375 in (9.5 mm) lead length, PCB mounted
onsemi 1N4001/D, mounting method 3	50 °C/W	3/8 in leads, 1.5 in × 1.5 in copper surface
onsemi, mounting method 1	52 / 65 / 72 °C/W	1/8 in, 1/4 in and 1/2 in lead length, still air
onsemi, mounting method 2	67 / 80 / 87 °C/W	1/8 in, 1/4 in and 1/2 in lead length, still air
Diodes DS28002 rev. 11-3	100 K/W	Leads held at ambient 9.5 mm from the case

Worked example. onsemi specifies maximum full-cycle average forward voltage of 0.8 V at IO = 1.0 A with 1 inch leads, so a 1N4007 rectifying at full rating dissipates about 0.8 W. In a 60 °C enclosure:

• At 50 °C/W the junction rises 40 °C to 100 °C. Against the 150 °C limit that is 50 °C of margin.
• At onsemi’s worst tabulated 87 °C/W the rise is 70 °C, giving 130 °C and 20 °C of margin.
• At the Diodes figure of 100 K/W the rise is 80 °C, giving 140 °C and 10 °C of margin.

Same part number, same 0.8 W, and the difference between comfortable and marginal is entirely lead length and copper. Short leads and a 5 mm × 5 mm copper pad at each end, which is what Vishay’s derating curve assumes, are worth more than a bigger diode.

Mounting and soldering limits

The numbers are tight and they differ by vendor, so take the lowest that applies to your part.

• onsemi: 260 °C maximum for 10 s, measured 1/16 in (1.6 mm) from the case.
• Vishay: solder dip 275 °C maximum for 10 s per JESD 22-B106.
• Diodes: 260 °C maximum for 30 s per J-STD-020, and moisture sensitivity Level 1, so no bake before assembly.
• Bend leads away from the body, never at it. The lead-to-body seal is the weak point, and within 1.27 mm of the body the lead diameter is not even controlled.

Mount horizontally when you can. Short leads pull heat into the copper, which is exactly what the 50 °C/W figure assumes. Vertical mounting halves the board area and raises thermal resistance, because one lead now runs up into still air instead of into a pad.

Lead finish is bright or matte tin on all four vendors, solderable per MIL-STD-202 Method 208 or J-STD-002. Vishay’s E3 suffix carries JESD 201 class 1A whisker qualification, which matters if the board goes anywhere near a long-life or high-reliability programme.

DO-41 against the neighbouring axial packages

Package	Body (L × Ø)	Typical rating	Canonical part	Notes
DO-35 (DO-204AH)	4.0 mm × 2.0 mm	300 mA	1N4148	Signal diode; glass body
DO-41 (DO-204AL)	5.2 mm × 2.7 mm	1.0 A	1N4001–1N4007	The general-purpose rectifier default
DO-15 (DO-204AC)	7.6 mm × 3.6 mm	1.5 A	1N5391–1N5399	Drop-up when 1 A runs hot
DO-201AD	9.5 mm × 5.2 mm	3.0 A	1N5400–1N5408	Thicker leads; will not fit a DO-41 hole
SMA (DO-214AC)	surface mount	1.0 A	S1A–S1M	The SMD path Diodes points 1N400x users toward

The ladder is deliberate: 1N4004, 1N5395 and 1N5404 are all 400 V parts at 1 A, 1.5 A and 3 A. Moving up the ladder for thermal headroom keeps the voltage rating and changes only the package and the hole size. [INTERNAL LINK: DO-201AD package -> DO-201AD axial rectifier dimensions and footprint]

What ships in DO-41 today

Part	Type	Ratings	Sourcing note
1N4001–1N4007	Standard recovery, 2 µs trr	50 V to 1000 V, 1 A, IFSM 30 A, I²t 3.7 A²s	The default. Vishay 1N4004-E3/54 about $0.16 at qty 1
1N4004 (Good-Ark)	Standard recovery	400 V, 1 A	$0.15 at qty 1, down to $0.0153 at 250 k
1N4004-TP (MCC)	Standard recovery	400 V, 1 A	68,833 in stock, 16-week factory lead time
UF4007	Ultrafast, 75 ns trr	1000 V, 1 A	$0.54 at qty 1. Use where 1N4007 is too slow
BA159	Fast recovery, 500 ns trr	1000 V, 1 A	Middle ground on speed and price
1N5817 / 1N5818 / 1N5819	Schottky	20 V / 30 V / 40 V, 1 A, VF 450 mV to 600 mV	Low drop, high leakage, low voltage
SB240S	Schottky	40 V, 2 A, VF 550 mV at 2 A	2 A in DO-41; the package is not limited to 1 A

Lifecycle is the part nobody documents. onsemi’s data sheet lists every non-Pb-free 1N400x variant as discontinued, leaving only the G-suffix parts. Diodes’ DS28002 carried a not recommended for new design flag steering users to the S1A–S1M SMA series, and DigiKey shows Vishay’s 1N4004GP-E3/54 as not for new designs while the plain 1N4004-E3/54 stays active. Check the exact ordering part number, not the 1N400x family.

Counterfeits are common because the parts are cheap and the marking is trivial to print. Genuine onsemi devices carry an assembly-location letter, the device number, a two-digit year and work week, and a Pb-free microdot. A reel with no date code, or with identical date codes across supposedly separate lots, is worth a reverse-leakage check at rated voltage before it reaches a board. [INTERNAL LINK: counterfeit screening -> detecting counterfeit and remarked semiconductors]

Specifying a DO-41 part

1. Fix the drill from the widest lead you might ever receive: 1.1 mm for a 0.90 mm lead at IPC Level B. Do not size it from one vendor’s 0.86 mm.
2. Set horizontal pitch at 10.16 mm so the bend clears the uncontrolled zone at the body.
3. Compute junction temperature with the RθJA that matches your actual lead length and copper, not the best number on any datasheet.
4. If the answer leaves under about 25 °C of margin at maximum ambient, step up to DO-15 or DO-201AD rather than adding copper.
5. Check reverse recovery. A 1N4007 at 2 µs is fine at 50 Hz or 60 Hz and wrong in anything switching. UF4007 or BA159 are the same package and footprint.
6. Verify the ordering part number’s lifecycle status and lead time before releasing the BOM.

Frequently asked questions

What are the dimensions of a DO-41 package?

Body length 4.10 mm to 5.20 mm, body diameter 2.00 mm to 2.70 mm, lead diameter 0.71 mm to 0.86 mm, and at least 25.40 mm of lead at each end. Diodes allows 2.72 mm on the body and MCC allows 0.90 mm on the lead, so design footprints to the wider figures.

What hole size do I use for a DO-41 diode?

1.1 mm finished hole with a 1.5 mm pad covers IPC-2222 Level B against a 0.90 mm worst-case lead. Level A pushes the drill to 1.2 mm and the pad to 1.7 mm. Going below 1.0 mm is asking for insertion problems with parts from a second source.

Is DO-41 the same as DO-204AL?

Yes. DO-204AL is the current JEDEC registration for the outline originally called DO-41, and both names appear together on datasheets and distributor filters. You will also see SOD66 and, in KiCad’s library naming, SOD81 for the same body. Search DO-204AL for the best parametric results.

What is the difference between DO-41 and DO-35?

Size and current. DO-35 is a 4.0 mm × 2.0 mm glass signal-diode body typified by the 1N4148 at 300 mA. DO-41 is a 5.2 mm × 2.7 mm rectifier body typified by the 1N400x series at 1.0 A. The DO-41 lead is also thicker, so the two do not share a footprint.

How much current can a DO-41 diode handle?

One amp average is the usual rating, at 0.375 in lead length and 75 °C ambient. The package itself is not the limit: 2 A Schottky parts such as the SB240S ship in DO-41. What actually caps it is junction temperature, which depends on your lead length and copper area.

What is the SMD equivalent of a DO-41 diode?

SMA, also called DO-214AC. The S1A through S1M series matches the 1N4001 to 1N4007 voltage ladder at the same 1 A, and Diodes has explicitly pointed 1N400x users at it. Expect different thermal behaviour, since an SMA sinks heat into pads rather than long leads.

What to do next

Build one DO-41 footprint at 1.1 mm hole, 1.5 mm pad, 10.16 mm pitch and make it the library default; it accepts every vendor’s part and keeps the lead bend out of the uncontrolled zone. Then check the thermal case honestly: if your design dissipates more than roughly 0.8 W in the part, or ambient runs above 60 °C, work the junction temperature with the RθJA that matches your real lead length before you commit. If that leaves under about 25 °C of margin, move to DO-15 or DO-201AD now, while it is a library change rather than a respin.