Name | Notes | |
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![]() | endcap | used on 2-pin “chip” packages |
![]() | gull-wing | common on semiconductor packages, especially for components with more than two pins (this terminal shape is also called L-lead) |
![]() | lug-lead | pins extend flat from the bottom, used on some diode packages (this terminal shape is also called flat-lead) |
![]() | inward-L | used on 2-pin “molded” packages, such as tantalum capacitors (note how the pin folds underneath the package) |
![]() | J-lead | components with J-lead terminals can be soldered on the PCB or be inserted in a socket PLCC packages use J-lead extending from all four edges |
![]() | no-lead | notably QFN and DFN packages on occasion, pads are “pulled back” from the edges (PQFN for Pulled-back, Quad Flat No-lead) |
![]() | ball-grid | |
![]() | land-grid | similar to ball-grid, but flat contact surfaces instead of solder balls may be used with a needle-pin connector, or be reflow soldered |
![]() | castellated | common for modules, occasionally used on resistor arrays on 2-pin components, this terminal style is also called side-concave |
The normal orientation is the orientation that the component has when its rotation is zero degrees. There are two predominant standards for the normal orientation of components on a PCB. Fortunately, these two standards, IPC-7351 and IEC 61188-7 “Level A”, are compatible with each other.
In brief, the normal orientation of 2-pin packages is such that pin 1 is on the left and pin 2 is on the right. For polarized components, such as electrolytic or tantalum capacitors, pin 1 is the “plus”-pin. For diodes, pin 1 is the cathode. For packages with more than 2 pins, the component is oriented as such that pin 1 is aligned to the top left corner. If pin 1 is in the middle of an edge, instead of near a corner, pin 1 must be aligned to the top. A few exceptions to these general rules are noted beneath the table.
Most surface mount components come packaged in tape, on reel. A separate standard exists for how the components are packaged in carrier tape, EIA-481. Manufacturers generally adhere to the EIA-481 standard, but many also specify exceptions for specific component packages; for example, many manufactures have continued to package QFP and QFN packages according to the rules in EIA-481C instead of adopting the changes of EIA-481D.
The table below shows the normal orientations according to IPC-7351 and the packaging orientation according to the latest EIA-481 standard. The angle by which a package must be rotated to go from EIA-481 to IPC-7351 is also given.
Note that EIA-481 only applies to packaging in tape; see the notes at the end of this section for tube and tray packaging.
EIA-481D | IPC-7351 | Notes | |
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Non-polarized chip or moulded packages, e.g. resistors, capacitors, inductors, 2-pin crystals. |
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Polarized chip or moulded packages (except capacitors, see below). For diodes, pin 1 is the cathode. |
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Tantalum capacitors or other capacitors in moulded packages. Pin 1 (with a bar) is the positive pole. |
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Electrolytic capacitors. Pin 1 is the positive pole. (The black bar marks the negative pole.) |
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Power inductors (non-polarized). |
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PLCC2 package (for LEDs). See also the notes below. |
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PLCC4 and PLCC6 packages (for multi-colour LEDs). See also the notes below. |
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Resistor arrays and capacitor arrays in a chip package. | |
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Ceramic resonators with 3 pins. See the notes below for crystals and oscillators with two or four pins. |
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Rectangual 4-pin crystals. See the notes below for crystals with two pins, and oscillators with a square shape. | |
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3-pin SOT style transistor, e.g. SOT23, SOT323, SOT523, SC70, TO-236. |
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5-pin SOT style packages, e.g. SOT23-5, SC70-5, SSOP-5. |
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6-pin & 8-pin SOT style packages, e.g. SOT23-6, SC70-6, SSOP-6. |
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SOT143 and SOT343. |
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SOT223, SC73, TO-89, TO-261. (See below for similar packages.) |
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SOT89, TO-293. (See above and below for similar packages.) |
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DPAK D2PAK, TO-220, TO-252, TO-263. (See above for similar packages.) |
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Rectangular IC packages: SOIC, SSOP, TSSOP, TSOP type 2 (but see below for TSOP type 1). | |
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TSOP type 1. |
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Square IC packages: QFP, QFN, SON, DFN (but not BGA and most PLCC, see below). |
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Square IC packages that have pin 1 in the middle of the row, which is common for PLCC packages. | |
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Square Grid array IC packages (BGA, LGA, PGA); see above for QFN, QFP and other square IC packages. |
The low pin count PLCC packages for LEDs have a chamfered corner to mark pin 1. For PLCC2, pin one is usually the cathode (conforming to IPC-7351); for RGB LEDs in PLCC4 and PLCC6 packages, pin 1 is typically the common anode.
The PLCC4 package uses a clockwise pin numbering scheme, starting from pin 1 in the upper left corner. The zero-orientation is not explicitly defined in the IPC-7351 standard (because IPC-7351 assumes a counter-clockwise pin numbering).
The PLCC6 package uses a counter-clockwise pin numbering scheme, similar to dual-line IC packages.
Crystals in a 2-pin chip package follow the orientation of 2-pin non-polarized chip packages. Ceramic resonators with three aligned pins are oriented as shown in the table.
For crystals and crystal oscillators with four pins (or more), the orientation in tape is inconclusive. Rectangular shaped crystals generally follow the alignment as shown in the table. Square packages (which are typically oscillators, rather than crystals) regularly use the orientation of PLCC4.
4-pin crystals and oscillators may use a clockwise pin numbering, like PLCC4. For crystals, the pin numbering direction is mostly irrelevant, because the crystal is typically connected between pins 1 and 3 (with pins 2 and 4 either unconnected, or both connected to ground). Regardless of the direction of the pin numbering, pins 1 & 3 are at the same positions.
Components are oriented sideways in tube (sticks), such that the pins of consecutive components do not touch. The end of the tube that “pin 1” of the component points to is often marked with a green stop or pin.
JEDEC trays have a chamfered corner. If the tray is oriented such that the chamfered corner is on the upper left, the components in the tray are oriented according to IPC-7351.