ODA Pad Stack Naming Convention

The pad stack consists of combinations of letters and numbers that represent shape, or dimensions of lands on different layers of printed boards or documentation. The name of the pad stack needs to represent all the various combinations. This pad stack naming convention was created by Optimum Design Associates.

Name Derivation: A pad stack name is a deterministic function of the pad stack geometry and the selected naming convention. It is not an attribute stored on the pad stack. The name shall be regenerated whenever the geometry changes, whenever the selected naming convention changes, and at the point where library or CAD output is produced - regardless of how the pad stack was originally created.

A name may be overridden manually. An overridden name shall be flagged as such and shall be the only case in which a stored string survives regeneration.

The first part of the pad stack convention consists of a land shape. There are six basic land shape identifiers. Note: All alphabetical characters are "UPPER CASE". All numeric values are represented in Micrometer units. All numeric values are represented in micrometer units, zero padded to a minimum of four digits. This applies uniformly to every dimension in a pad stack name - pads, lands, solder mask, solder paste, corner radii, tolerances, offsets, holes, slots and drills alike. A value requiring more than four digits is written at its natural width (e.g. 12.00 mm becomes 12000). Conversion examples: 1.500 mm = 1500; 0.860 mm = 0860; 0.90 mm = 0900; 0.25 mm = 0250; 4.00 mm = 4000; 0.050 mm = 0050.

Illegal characters:

" " , ; : / \ [ ] ( ) . { } * & % # $ ! @ ^ =

Maximum length: A pad stack name shall not exceed 31 characters. Where a generated name would exceed the limit, generation shall fail with a diagnostic rather than emit a truncated or altered name.

Surface Mount Rectangle 2.000 X 1.000

Through-hole Plated 0.90 Hole, Circular 1.500 Pad

Surface Rounded Corner Rectangle 2.430 long X 2.370 short X 0.050 corner radius

Modifier Order: Where more than one modifier applies, they are appended in this fixed order: 1. internal layer modifier (_INP); 2. solder paste modifiers (_SSP, _NSP, _TSP, _BSP); 3. solder mask modifiers (_1TO1, _SSM, _NSM, _TSM, _BSM, _STM, _SBM, _TNTT, _TNTB, _CAPT, _CAPB); 4. miscellaneous modifiers (_OFF, _TOL, _OBS, _PFIT, _UV, _PCH, _VT, _BWT). Example: MHP4000C7000_INP5200_SSM7200 (the internal layer pad callout precedes the mask callout).

'X' is used to separate dimensions within a given shape, and '_' is used to separate the different aspects of the naming convention.

Example: SR0640X0630_SSM0660X0650 (Selective Solder Mask callout appended when the mask deviates from the standard overage of .05 on each side / .1 overall expansion. In this example, .01 on each side / .02 overall expansion is used.)

Shape Deviation: When a solder mask or solder paste layer is a DIFFERENT SHAPE from the copper pad, the callout carries the shape letter before the dimensions, so the layer is fully described: _SSM + shape letter + dimensions, and _SSP + shape letter + dimensions.

Example: SC0230_SSPRCR0250X0250X0050 - Circular copper 0.230, standard solder mask (no callout required), selective solder paste as a rounded corner rectangle 0.250 X 0.250 with 0.050 corner radius.

When the shape matches the copper, the shape letter is omitted and the dimensions alone follow the modifier, e.g. SR3000X1500_SSM3300X1800.

Per-layer corner radius: each layer carries its own shape AND its own corner radius, appended as a final X value in the same form used by SRCR. Copper, solder mask and solder paste may each be a different shape with a different corner radius, and each is described in its own callout. A corner radius stated for one layer never applies to another.

Any time the pad is longer on one side than the other, the longest edge is presented first in the pad stack naming convention.

Chamfered corner pad stacks are named as custom pad stacks using the SU_ prefix per the User Defined / Custom Pad Stacks section. Drawing the chamfer at the CAD tool footprint level instead remains permitted for hand-authored parts, but automatic generation shall always produce an SU_ name.

Radius cornered pads fall under B obrounds (4 corners) or F fingers (2 corners). Rounded corner rectangles (where the corner radius does not form a full obround or finger) use the SRCR prefix: SRCR + long side X short side X corner radius value (e.g., SRCR2430X2370X0050). Any other non-standard corner configuration would fall under SU custom pad/pad stack naming.

Named specifically since they won't be used generically and are seen as being used 1 to 1 with a part number or package.

n = a positive integer, starting at 1, assigned per DISTINCT custom pad stack within that footprint. Two pins whose custom pad stacks are identical in geometry across every layer share the same n; pad stacks that differ in any way receive different numbers. Numbers are assigned in ascending pin order of first appearance, so that rebuilding the same footprint always yields the same names.

Example: SU_INFINEON_PG-TSDSON-8-FL_1, SU_INFINEON_PG-TSDSON-8-FL_2

Manual variants such as L and R remain permitted for hand-authored pad stacks but shall not be produced automatically.

SU_ManufacturerPrefix_CaseCode_#

Example:

 SU_TI_RRX0029B_1 (Texas Instruments, RRX0029B case code, pad variant 1)

In addition to the pad stack name, the individual pads and holes within a pad stack follow their own naming conventions. These names are derived from the parent pad stack name and describe the specific layer-level objects.

For surface mount pads, the individual pad name is derived from the pad stack name by removing the leading "S" prefix. The pad dimensions in the name remain identical to the pad stack.

Convention: Remove the "S" prefix from the pad stack name. The resulting name is assigned to the copper pad on most layers.

Solder Mask Pad: When solder mask uses the default expansion (0.05 mm per side / 0.10 mm overall), the mask pad name reflects the expanded dimensions using the same format.

Example: Pad stack SR0860X0250 → Copper pad name is R0860X0250 (assigned to most layers), Solder mask pad name is R0960X0350 (reflects the 0.05 mm per side expansion).

Holes within through-hole and mounting hole pad stacks are named to describe the hole shape, diameter, and plating status.

Convention: The hole name follows the format: Shape + Diameter + Plating Suffix.

Shape: "Rnd" for round holes.

Diameter: Expressed in millimeters (e.g., 0.40 for a 0.40 mm hole).

Plating Suffix: "P" for plated holes, "N" for non-plated holes.

Example: Rnd 0.40P = Round, 0.40 mm diameter, plated hole.

Example: Rnd 3.20N = Round, 3.20 mm diameter, non-plated hole.

Default tolerance: ±0.075 mm for holes up to 2.50 mm, and ±0.10 mm for holes larger than 2.50 mm. When the default tolerance applies, no suffix is appended to the hole name.

Non-default tolerance: When a tolerance other than the default is required, a _TOL suffix is appended to the hole name. The suffix value is expressed in micrometers representing the ± tolerance.

Example: Rnd 0.40P_TOL0050 = Round, 0.40 mm, Plated, with ±0.05 mm tolerance (instead of the default ±0.075 mm).

Example: Rnd 3.00P_TOL0150 = Round, 3.00 mm, Plated, with ±0.15 mm tolerance (instead of the default ±0.10 mm).

Footprint names follow IPC-7351 conventions where applicable. The material condition suffixes L, N, and M are used when the IPC nominal land pattern is selected.

When the IPC nominal land pattern is used, the standard IPC material condition suffixes apply:

Example: SOT23-5P95_290X280X145L45X40N

If the package type is an IPC standard one but the manufacturer-recommended footprint is chosen instead, the Q material condition suffix is used per our standard in place of L, N, or M, followed by the manufacturer prefix and the case code.

Example: SOT23-5P95_290X280X145L45X40Q_TI_DBV0005A

If the package type is not an IPC standard one, or if it is an RF component, the manufacturer-recommended footprint is used and named with the manufacturer prefix and case code directly.

Example: TI_RRX0029B