A DIP-6 package is a six-lead through-hole dual in-line body on 2.54 mm pitch with 7.62 mm row spacing. Those two numbers are fixed across the industry. Body length is not. onsemi ships 6-pin optocouplers on a 7.12 mm body and on an 8.51 mm body, both labelled PDIP6. This article gives the verified outlines, the pinouts you will actually meet, and a land pattern you can drill.
[IMAGE 1: Top and side view of a 6-lead plastic DIP optocoupler with pitch, row spacing, body length and standoff dimensioned | alt: “DIP-6 package dimensions showing 2.54 mm pitch and 7.62 mm row spacing”]
Key takeaways
- Pitch is 2.54 mm and row spacing is 7.62 mm. Everything else varies by supplier and by part family.
- Body length ranges from 7.12 mm to 8.51 mm across two onsemi outlines that share the PDIP6 name. Draw your courtyard for the longer one.
- Pin 5 is the phototransistor collector on a 4N35 and the triac substrate on a MOC3021M. On the MOC part it must be left unconnected.
- External creepage and clearance are typically 7 mm. The 0.4 in lead-spacing option raises clearance to 10 mm without changing the die or the pinout.
- KiCad’s stock DIP-6 footprint uses a 0.8 mm drill. That is IPC-7251 Level C, not the Level B most house rules assume.
What a DIP-6 package is
DIP-6 is a plastic dual in-line package with three leads per row, six leads total, on 0.100 in (2.54 mm) centres with 0.300 in (7.62 mm) between the rows. Leads are formed for through-hole insertion. The body is moulded epoxy. Pin 1 sits at the notch or dot and numbering runs counterclockwise viewed from above.
That definition is the snippet answer. The useful part is what it leaves out.
JEDEC registers the 0.300 in DIP family under MS-001, but the published variations start at 8 leads and run upward — MS-001BA is the 8-lead outline, AA is 14, BB is 16, AC is 18, AD is 20, AF is 24. There is no widely cited 6-lead variation. Every supplier of 6-pin DIP parts therefore publishes a house outline instead: Vishay calls it DIP-6, onsemi assigns CASE 646-series numbers, Toshiba calls it DIP6, Infineon calls it PG-DIP-6-903. Those outlines are not interchangeable in every dimension.
The other thing worth knowing up front: the 6-lead DIP body is used almost exclusively for optically isolated devices. Phototransistor optocouplers (4N25 through 4N37, MCT2E, the H11A family), triac driver optocouplers (MOC3010M through MOC3023M) and photovoltaic relays all live here. If you are looking at a DIP-6 package, you are almost certainly looking at an isolation barrier, and the rules that matter are creepage rules.
DIP-6 package dimensions across suppliers
The table below is built from the mechanical drawings in the datasheets, not from aggregator listings. Every row traces to a document number and revision.
| Outline (source doc) | Body length | Body width | Pitch | Row spacing | Lead span | Standoff / lead |
| Vishay DIP-6, drawing 14771_2 (4N35, doc 81181) | 7.12 ± 0.3 mm | 6.50 ± 0.3 mm | 2.54 mm | 7.62 mm typ. | 7.62 to 9.5 mm typ. | 0.5 ± 0.1 mm standoff, 0.25 mm lead thickness |
| onsemi CASE 646CU / 646CG / 646CV (4N35) | 7.12 mm | 6.50 mm | 2.54 mm | 7.62 mm | not stated in text block | see case drawing |
| onsemi CASE 646BX / 646BY / 646BZ (MOC301XM, MOC302XM) | 8.51 mm | 6.35 mm | 2.54 mm | 7.62 mm | not stated in text block | see case drawing |
| Vishay DIP-6, legacy outline i178004 (doc 81787, 2007) | 8.50 to 8.70 mm | 6.30 to 6.50 mm | 2.54 mm typ. | 7.62 mm typ. | 7.62 to 8.81 mm | 1.00 mm min. standoff, lead 0.45 to 0.55 mm wide |
| KiCad generic DIP-6_W7.62mm fabrication outline | 7.62 mm | 6.35 mm | 2.54 mm | 7.62 mm | n/a (land pattern) | courtyard 10.55 × 8.15 mm |
Read the first and third rows together. Two onsemi optocouplers, both described as 6-pin DIP, differ by 1.39 mm in body length and 0.15 mm in body width. A silkscreen outline drawn around the 4N35 will be overrun by a MOC3021M dropped into the same footprint. The pads still line up, so the board assembles and the error only shows up as a silkscreen violation or a courtyard collision in DRC.
Practical rule: draw the DIP-6 courtyard for a 8.7 × 6.6 mm body. That covers every outline in the table with margin and costs you nothing on a 0.1 in grid.
DIP-6 pinout depends on the device, not the package
The package fixes six positions. It fixes nothing about what those positions do. Two of the most common DIP-6 parts assign pin 5 to opposite functions, and one of them is a trap.
| Pin | 4N35 / 4N36 / 4N37 | MOC3010M – MOC3023M | Consequence |
| 1 | LED anode | LED anode | Same |
| 2 | LED cathode | LED cathode | Same |
| 3 | No connection | No connection | Same |
| 4 | Emitter | Main terminal | Output side, different device |
| 5 | Collector | NC — triac substrate, do not connect | Wiring pin 5 on a MOC part connects the triac substrate |
| 6 | Base | Main terminal | The 4N35 base pin allows an external base-emitter resistor |
onsemi marks pin 5 on the MOC301XM and MOC302XM series “DO NOT CONNECT (TRIAC SUBSTRATE)”. Designers who reuse a 4N35 footprint and leave pin 5 tied to a net inherit a connection to the substrate of a 400 V bilateral switch. It is a substitution error, not a layout error, and it does not show up until the part is populated.
The 4N35 base pin is the reason the part is a 6-pin device at all. A base-emitter resistor sets the trade between speed and current transfer ratio. Leave it open when you want CTR, fit 10 kΩ to 100 kΩ when you want turn-off speed.
[IMAGE 2: Side-by-side pinout diagrams for a 4N35 and a MOC3021M in the same DIP-6 outline, pin 5 highlighted | alt: “DIP-6 pinout comparison 4N35 versus MOC3021M showing pin 5 difference”]
DIP-6 footprint: hole size, pad size and courtyard
Start from the lead, not from a library part. Vishay’s DIP-6 outline gives a maximum lead cross-section of 0.55 mm wide by 0.30 mm thick.
Maximum lead diagonal:
√(0.55² + 0.30²) = √0.3925 = 0.63 mm
IPC-7251 sets a hole diameter factor above the maximum lead for each producibility level: 0.25 mm for Level A, 0.20 mm for Level B and 0.15 mm for Level C. Applied to 0.63 mm:
| Density level | Minimum finished hole | Practical drill | Use when |
| A (maximum, low density) | 0.88 mm | 0.90 mm | Hand assembly, rework-heavy builds, thick boards |
| B (nominal) | 0.83 mm | 0.85 mm | Default for most through-hole assembly |
| C (minimum, high density) | 0.78 mm | 0.80 mm | Tight routing channels, machine insertion only |
Now check the library part you were about to use. KiCad’s official DIP-6_W7.62mm_LongPads footprint specifies a 0.8 mm drill with 2.4 × 1.6 mm oval pads. That is the Level C column. It is a defensible choice, but it is not the Level B most house rules assume, and it leaves 0.085 mm of radial clearance around a worst-case lead.
If your fabricator quotes ±0.075 mm on finished hole size and your assembler hand-inserts, move to 0.85 mm and stop fighting bent leads at first article.
The rest of the KiCad DIP-6 package footprint is sound and worth copying: pin 1 is a rectangular pad, pins 2 to 6 are ovals, pads sit at (0, 0), (0, 2.54), (0, 5.08), (7.62, 5.08), (7.62, 2.54) and (7.62, 0), and the courtyard runs 10.55 mm by 8.15 mm. The rectangular pin 1 pad survives a silkscreen print failure, which a silkscreen dot does not.
Creepage, clearance and the 0.4 in lead-spacing option
This is where the DIP-6 package earns its keep, and where the datasheet numbers diverge more than the mechanical ones.
| Parameter | Vishay 4N35 | onsemi 4N35 | onsemi MOC302XM |
| Isolation test voltage | 5000 V RMS | 5000 V AC RMS, 1 min (UL1577) | 4170 V AC RMS, 1 min (UL1577) |
| External creepage | ≥ 7 mm | ≥ 7 mm | ≥ 7 mm |
| External clearance | ≥ 7 mm | ≥ 7 mm | ≥ 7 mm |
| Clearance, 0.4 in lead option | wide-lead options published separately | ≥ 10 mm (option TV) | ≥ 10 mm (option TV) |
| Distance through insulation | ≥ 0.4 mm | ≥ 0.4 mm | ≥ 0.5 mm |
| Maximum working insulation V | not stated | 850 V peak (V_IORM) | 850 V peak (V_IORM) |
| Highest allowable over-voltage | not stated | 6000 V peak (V_IOTM) | 6000 V peak (V_IOTM) |
| Comparative tracking index | 175 | 175 | 175 |
| Climatic classification | not stated | 55/110/21 | 40/85/21 |
Three things fall out of that table.
First, identical package, different UL1577 rating. 5000 V RMS on the 4N35 and 4170 V RMS on the MOC302XM series. The DIP-6 package outline tells you nothing about the isolation rating. Read the part datasheet every time.
Second, the option TV part number suffix gives you 10 mm of external clearance instead of 7 mm by bending the leads out to 0.4 in spacing. The die, the pinout and the body are unchanged. If a safety review is asking for more clearance, this is far cheaper than redesigning around a wider isolator. It does change your footprint: row spacing goes from 7.62 mm to 10.16 mm.
Third, distance through insulation differs by family on the same body — 0.4 mm for the 4N35, 0.5 mm for the MOC302XM. Reinforced-insulation arguments under IEC 60747-5-5 depend on that number.
One legacy trap: Vishay’s DIL300-6 metric outline is specified at greater than 6 mm creepage and 6 mm air path, not 7 mm. The wide DIL400-6 version is greater than 8 mm. If a compliance file cites a 6 mm figure, it is quoting that older outline, not the current DIP-6.
[IMAGE 3: Cross-section showing creepage path, clearance path and distance through insulation on a 6-pin DIP optocoupler, with 7 mm and 10 mm variants side by side | alt: “DIP-6 package creepage and clearance with standard and 0.4 inch lead spacing”]
Lead-form options and the surface-mount versions
A DIP-6 part is not necessarily through-hole. All three major suppliers sell the same moulded body with the leads formed differently, and the option code lives in the part number suffix.
| Supplier | Option codes | What changes |
| Vishay | Options 6, 7, 8, 9 | Option 6 spreads leads to 10.16 – 10.92 mm. Option 9 is a gull-wing SMD form with a 9.53 – 10.03 mm lead span and 0.10 mm maximum coplanarity. |
| onsemi | no suffix, S, SR2, V, TV | S is SMT lead bend, SR2 adds tape and reel, V adds the DIN EN/IEC 60747-5-5 option, TV is 0.4 in lead spacing plus the IEC option. |
| Toshiba | DIP6, DIP6(LF1), (LF2), (LF4), (LF5) | Four registered lead-forming variants of the same DIP6 body. |
| Infineon | PG-DIP-6-903 (SMT6) | Through-hole 6-lead body supplied in tape and reel for photovoltaic relays. |
Shipping format follows the option, and it affects your line more than the package does. onsemi ships the 4N35 at 65 units per tube and the MOC3010M at 50 units per tube. The lead-bent SMT versions come 1000 per reel, or 50 per tube for the MOC parts. If you are quoting a machine-placed build, a tube-only part number will cost you a hand-load station.
Soldering limits
Through-hole and lead-bent versions have completely different process windows.
For the through-hole part, Vishay specifies 260 °C for a maximum of 10 s dip soldering, with the requirement that solder stays at least 1.5 mm from the seating plane. That standoff requirement is the one people miss. A 0.5 mm nominal standoff and a generous wave-solder pot will put solder against the body, and the epoxy-to-lead interface is part of the isolation barrier.
For the SMT lead-bent version, onsemi publishes a lead-free reflow profile in the 4N35 datasheet:
- Preheat 150 °C to 200 °C for 60 to 120 s
- Liquidus 217 °C, held 60 to 150 s
- Peak body temperature 260 °C, +0 / −5 °C, no more than 30 s within 5 °C of peak
- Ramp-up 3 °C/s maximum, ramp-down 6 °C/s maximum
- Total time from 25 °C to peak: 8 minutes maximum
Absolute lead solder temperature for both onsemi families is 260 °C for 10 s.
Failure modes worth designing against
The DIP-6 package itself rarely fails. The device inside it degrades predictably, and the surrounding design usually decides whether that matters.
CTR degradation
The LED dims with accumulated current and junction temperature, so current transfer ratio falls over life. Würth Elektronik’s application note ANO006a works a representative case: an accelerated test at 110 °C and 30 mA, compared against field use at 5 mA and 80 °C, yields an acceleration factor of 218, so 1000 test hours model roughly 25 years of service.
Design against end-of-life CTR, not the datasheet minimum. Reduce LED drive current, keep duty cycle low, and clamp transient LED current. All three extend life more than picking a higher CTR bin does.
Copper under the barrier
A 7 mm external creepage rating is meaningless if a trace or a plane runs under the body between the input and output pin rows. Keep the isolation gap free of copper on every layer, including inner layers, and cut a slot if the board stack forces you close.
Second-source body growth
Covered above, and it belongs on this list. A part swap from a 7.12 mm body to an 8.51 mm body inside a released DIP-6 package footprint will pass electrical test and fail a mechanical fit check against an adjacent connector.
Pin 3 assumptions
Pin 3 is a no-connect on both families shown here, but it is a mechanical lead in the mould. Do not route a signal through the pin 3 pad and do not use it as a via. It crosses the isolation gap.
Sourcing and availability check
Silicon in the DIP-6 package is generally cheap and widely stocked. The accessories are not. A CNC Tech 243-06-1-03 six-position 0.3 in DIP socket lists at USD 0.30 in single quantity on DigiKey, with zero stock and a 20-week manufacturer lead time at the time of writing. If your design assumes a socketed DIP-6 optocoupler for field replacement, qualify a second socket source before release.
For the isolator itself, second sourcing is straightforward on the phototransistor families and less so on the triac drivers, where trigger current binning (5 mA, 10 mA, 15 mA and 30 mA across the MOC3010M to MOC3023M range) is the real constraint rather than the package.
Selection decision path
- Do you need galvanic isolation at mains potential? If no, a DIP-6 package is almost certainly the wrong choice; use a logic-level part in a small-outline body.
- What working voltage does the safety standard require? Compare against V_IORM of 850 V peak and confirm the creepage and clearance figures on the specific part.
- Is 7 mm of clearance enough? If not, order the option TV / 0.4 in lead-spacing version and lay out for 10.16 mm row spacing.
- Through-hole or reflow? Through-hole gives you the dip-soldering profile and tube packaging; the lead-bent option gives you tape and reel and a standard lead-free reflow profile.
- Draw the footprint from the lead dimensions and your density level, not from a library default. Then widen the courtyard to cover the longest body in your approved vendor list.
Frequently asked questions
What is a DIP-6 package?
A DIP-6 package is a six-lead plastic dual in-line package with three leads per row on 2.54 mm pitch and 7.62 mm row spacing, formed for through-hole mounting. It is used almost exclusively for optically isolated devices such as phototransistor optocouplers and triac driver optocouplers.
What are DIP-6 package dimensions in mm?
Pitch is 2.54 mm and row spacing is 7.62 mm on every DIP-6 outline. Body size varies: Vishay’s 4N35 drawing gives 7.12 ± 0.3 mm by 6.50 ± 0.3 mm, while onsemi’s MOC302XM case outline is 8.51 mm by 6.35 mm. Always check the specific case drawing.
Is DIP-6 the same as DIP6, PDIP-6 or DIL-6?
They refer to the same six-lead through-hole body. PDIP specifies plastic, DIL is the older European term, and suppliers use their own spelling — Vishay writes DIP-6, Toshiba writes DIP6, onsemi writes PDIP6. The names are equivalent; the dimensional drawings behind them are not always identical.
What drill size should a DIP-6 footprint use?
Work from a 0.63 mm maximum lead diagonal. IPC-7251 gives 0.90 mm for Level A, 0.85 mm for Level B and 0.80 mm for Level C. KiCad’s stock DIP-6 footprint uses 0.80 mm, which is Level C. Move to 0.85 mm if the board is hand-assembled or reworked.
Can a DIP-6 optocoupler be surface mounted?
Yes. Suppliers form the leads outward into a gull-wing shape and sell the result as an SMT option — Vishay Option 9, onsemi suffix S or SR2, Toshiba LF codes. The body is unchanged. The SMT versions ship in tape and reel and use a standard lead-free reflow profile peaking at 260 °C.
Do all DIP-6 parts have the same pinout?
No. Pins 1 and 2 are the LED anode and cathode on the common families, but the output side differs. On a 4N35 pins 4, 5 and 6 are emitter, collector and base. On a MOC3021M pins 4 and 6 are the main terminals and pin 5 is the triac substrate, which must be left unconnected.
What to do next
If you are laying out a board now: build the DIP-6 package footprint from a 0.85 mm drill and a 1.6 mm pad, size the courtyard for an 8.7 × 6.6 mm body, and keep every layer clear across the isolation gap.
If you are qualifying a second source: compare case outline numbers, not package names, and re-check distance through insulation and UL1577 rating on the alternate part.
If a safety reviewer has asked for more clearance: order the 0.4 in lead-spacing option and re-spin the footprint to 10.16 mm row spacing. It is a two-hour change and it buys 3 mm.
[IMAGE 4: Annotated DIP-6 land pattern with pad, drill, courtyard and isolation keep-out dimensioned | alt: “DIP-6 package footprint with 0.85 mm drill, 1.6 mm pads and isolation keep-out”]
Internal links to place
- [INTERNAL LINK: optocoupler CTR derating → optocoupler selection and CTR lifetime guide]
- [INTERNAL LINK: IPC-7251 through-hole land patterns → through-hole footprint design standards]
- [INTERNAL LINK: DIP-8 package → DIP-8 dimensions and pinout reference]
- [INTERNAL LINK: creepage and clearance calculation → isolation spacing on mains-referenced PCBs]
