Same function is not the same part. Every swap below keeps the diode's job — rectify, clamp, block — but the package, the recovery time or the voltage margin moves with it, and that is where repairs fail. 1N4448 and 1N914B drop straight into a 1N4148's DO-35 holes, and 1N5819 drops into a 1N5817. The 1N4007's commonest modern swap is the SMA-bodied M7 or S1M: the same die class carried on surface-mount pads rather than the same footprint. What no substitute covers is using a 1N4007 where a 1N4148 failed — the circuit passes a DC check and fails the moment the diode has to switch.
Table of Contents (8 points)
The substitutes, and what each one actually changes
Levels mean what they say. A drop-in needs no board or firmware change; pin-to-pin matches the footprint but wants a clock or initialisation check; functional matches the job without claiming the same footprint — almost always because the package moved from through-hole to surface-mount.
| Original | Package | Verified substitute | Level | What changes |
|---|---|---|---|---|
| 1N4007 | DO-41 axial | M7 | functional | SMA pads, not the DO-41 holes — the standard SMD migration for a 1N400x line |
| 1N4007 | DO-41 axial | S1M | functional | Same SMA pads as M7; only the laser marking differs |
| 1N4007 | DO-41 axial | 1N5408 | functional | Heavier leads — check hole size and annular rings on tight boards |
| 1N4148 | DO-35 glass | 1N4448 | drop-in | Same DO-35 body and 0.5 mm leads, same band orientation |
| 1N4148 | DO-35 glass | 1N914B | drop-in | Same DO-35 body and lead spacing |
| 1N4148 | DO-35 glass | LL4148 | functional | MiniMELF — needs a MELF-capable nozzle or gentle feeder settings |
| 1N5817 | DO-41 axial | 1N5819 | drop-in | Identical body, lead spacing and band orientation |
| 1N5817 | DO-41 axial | SS14 | functional | SMA pads, and SMA carries the smaller copper area — check dissipation |
| 1N5817 | DO-41 axial | 1N5822 | functional | 1.0 mm leads — verify on dense boards and check body height |
| 1N5817 | DO-41 axial | 1N5819HW-7-F | functional | SOD-123 pads; not the same land pattern as SOD-323 or SOD-123FL |
| FR107 | DO-41 / DO-15 | FR207 | functional | DO-15 leads (0.9 mm class) against the DO-41 0.8 mm class |
| FR107 | DO-41 / DO-15 | RL207 | functional | Standard recovery with a lower forward drop — check the printed marking |
| FR107 | DO-41 / DO-15 | HER208 | functional | DO-15; verify the marking to tell it from the FR207 in the same drawer |
| SS310 | SMC / SMB / SMA | SS38 | drop-in | Same package options — confirm which of the three the board carries |
| SS310 | SMC / SMB / SMA | MBRS3100 | drop-in | SMC land pattern, the largest of the three package scales |
| SS310 | SMC / SMB / SMA | SB5150 | functional | DO-201AD through-hole body with 1.0 mm-class leads |
Where the bench actually goes wrong
The 1N4148 is not usually counterfeited for its own sake; it fails through careless substitution and variant confusion. The classic repair error is dropping a 1N4007 in where a 1N4148 failed — cheap, on hand, and wrong: the 1N4007's recovery is roughly four times slower, so the circuit passes a DC test and fails at speed. If a 1N4148 came out, a 1N4148-class part goes back in.
The 1N5817 is the other trap, and it is a margin problem rather than a fit problem. Its 20 V rating is often chosen as "the cheapest Schottky", then run on a 12 V rail with almost no headroom for transients. The family is deep and the drop-in sibling is 1N5819 at 40 V — the honest question is which voltage grade to hold, not which is cheapest.
The 1N4007 has the opposite risk: it is never seriously short of supply, and it is one of the most relabelled parts in the spot market. Lots marked 1N4007 occasionally carry lower-voltage dies from the 1N4001-1N4004 grades, or refurbished pulls — a failure that only appears when the 1000 V margin is actually needed.
The migration these five are in the middle of
Four of the five families have already split into a through-hole original and a surface-mount successor: 1N400x into SMA-bodied M7 and S1M, 1N581x into SS14 and SOD-123 variants, FR107 into the DO-15 recovery classes, and SS310 into the SMA/SMB/SMC marking alphabet. New designs go to the SMD side; repair and small-batch work stays on the through-hole side, which is why both are still ordered in the same week.
The SS3x family is the clearest case of the naming problem: SS310, SR310, SK310 and MBRS3100 are largely the same 100 V / 3 A / 0.85 V die class from different fabs, so the marking tells you which fab and which land pattern — not which performance grade.
What we will not claim
A substitute is a starting point, not a clearance. Every mapping above was checked against the manufacturer datasheet for package, pinout and the ratings that decide a swap, and where the datasheet did not support a mapping no row was written — a wrong substitute costs more than a missing one. Confirm against your own schematic before a redesign, and treat the level column as the scope of the risk rather than a promise.
Parts named in this guide
CatalogEach of these is a part or part family this guide covers, linked to the catalog row we hold for it — specifications, package, lifecycle stage and the datasheet where we have localized one. Where the guide names a family, the row shown is the orderable part number we stock. A part the guide covers but that is missing from this list is one we do not currently carry; send the number and it goes out for sourcing with the rest.
| Part number | Manufacturer | Description |
|---|---|---|
| 1N4007Datasheet | onsemi | — |
| 1N4148 | Taiwan Semiconductor Corporation | — |
| 1N5817Datasheet | Taiwan Semiconductor Corporation | SCHOTTKY DO15 20V 1A 150C |
| FR107Datasheet | SMC Diode Solutions | — |
| SS310Datasheet | Taiwan Semiconductor Corporation | DIODE SCHOTTKY 100V 3A DO214AB |
| 1N4448Datasheet | Microchip Technology | Microchip Technology 1N4448 small-signal switching diode, 200 mA average rectified current, 75 V reverse voltage, 4 ns reverse recovery time, DO-35 axial package, through-hole. |
| 1N914B | onsemi | — |
| 1N5819Datasheet | Taiwan Semiconductor Corporation | SCHOTTKY DO15 40V 1A 150C |
| M7 | Yangzhou Yangjie Electronic Technology Co.,Ltd | DIODE GEN PURP 1KV 1A DO214AC |
| S1MDatasheet | onsemi | DIODE GEN PURP 1A DO214AC |
Put this to work on your component list
Send the part numbers or the whole BOM sheet. Each line comes back with current spot availability, original manufacturer condition, and verified cross-references — packed and shipped together in one single parcel.
How this guide is written
Written by the ICBOMS sourcing desk in Shenzhen and reviewed against the manufacturer documents and industry standards the guide cites. Statements are limited to what this desk does and how a part is judged — no indicative prices, lead times or stock counts, because those are quoted per line against a live check. Each guide carries the date it was last reviewed at the top of the page.