Letter Usage in the Zentroid SMD Naming Convention

Single letters are used to represent words in the Zentroid SMD Naming Convention. Using these letters before numerical values (prefix letters) indicates the form of SMD packages. Letters used after the last numerical values (suffix letters) indicate characteristics of the form described in the prefix. Following is a table of the letters that can be used in the first, second and third position of the prefix. A Zentroid prefix will be at least 2 letters long.

After the table I have listed the prefix and suffix letters with a complete description of their use. Finishing this page is a description of the letters used within the geometrical measurements of the packages.

Zentroid Prefix Letter Usage
Component Type Pin Group Form Pin Type
c - Capacitor a - Array b - Ball
d - Diode c - Chip c - Chip
f - Fuse d - Dual d - Dil
k - Socket f - Melf f - Flat
l - Coil/Inductor m - Molded g - Gull-Wing
o - Oscillator q - Quad i - Inline (in hole)
r - Resistor r - Radial j - J-Leg
s - Switch s - Single l - Leadless
u - Microchip t - T-Form or Tantalum s - Solder
x - Connector x - Axial v - Concave

udg - A Microchip with Dual rows of Gull-wing pins.


cae - Capacitor Aluminum Electrolytic

Prefix letters

a - ArrayAn array package is a package made up of multiple sections of the same base section. These are most often seen as chip packages but may be found in larger packages as well. Array is used in the two dimensional form when describing a uab or Microchip Array Ball. Here array simply means the balls are multiples in both the x and y directions.

b - BallBall is the pin type of a uab or the traditional name bga.

c - Capacitor/ChipAs a starting letter c starts a capacitor name. In any other position, a small package having 2 rectangular end caps as pins.

d - Diode/Dual/DilAs a starting letter d starts a diode name. As a second letter d refers to a package having 2 pin rows (Dual). In any other position of the prefix d refers to the pin type commonly referred to as Dil. These pins are pins that were designed originally for THT (through hole technology) packages. The pins are simply bent and cut off so the package can be used in (SMT) surface mount technologies.

e - EvenUsed when the pin widths of a resistor array chip all have the same width.

f - Fuse/Melf/FlatAs a starting letter f starts a fuse name. As a second letter f refers to a cylindrical package with 2 cylindrical end caps as pins. In respect to uab Bga packages f is used to indicate a flat pin even with the underside of the package. In any other position, a pin of the type that extends from the package body with its under side even with the under side of the package body.

g - Gull-wingA pin type that exits the side of the package and bends downward towards the pcb surface. As it meets the surface it is bent outwards extending further from the package.

j - J-legA pin type that exits the side of the package and bends downward towards the pcb surface. As it meets the surface it continues its bend inwards underneath the package and continues to bend upwards under the package.

k - SocketAs a starting letter k starts a socket name. A socket is defined as any holder of other devices that accommodates the electrical connections of the held device to a printed circuit board.

l - Coil/LeadlessAs a starting letter l starts a coil name. In any other position, a pin type that does not or very minimally extends beyond the package body.

m - MoldedMolded refers to almost all other packages than chip. It is the outer case of the package that supports the individual pins. Typically the case material is plastic. Molded also includes oscillator variants that have metal tops.

o - OscillatorThis starting letter indicates packages (the microchips therein) that generate oscillating voltage signals such as crystals.

q - QuadUsed to indicate a pin group form that has pin groups on all 4 sides of the package.

r - Resistor/Radial/Round pinAs a starting letter r starts a resistor name.

Radial - In the second position r indicates that the package has 2 or more pins protruding axially from one end of the package. In any other position, a pin type that is round such as a wire.

s - Switch/Single/SolderAs a starting letter s indicates packages that allow connections to be closed or opened (Switch). In the second position s means a pin group form that is a single row of pins.

As a pin type s indicates a special Zentroid pin type. This pin type is that of a pin that is most often completely covered by solder at it's end. AOI analysis of the solder joint is achieved through analysis of the form of the solder without determining where the pin end is located. This pin type is found on what the industry typically calls Sot packages.

t - T-FormThe Zentroid SMD Naming Convention uses a t in the second position of the prefix to name a pin group form that has a vertical row of 2 or more pins on the left and a single pin on the right at the middle height of the vertical row. Think of the t being rotated 90 degrees counter-clock wise.

In traditional terms a TO package or 3 pin SOT.

t has a second usage when associated with capacitors. The prefix ct indicates a capacitor of the Tantalum form.

u - MicrochipZentroid uses the starting letter u to indicate "Microchip". The word "Microchip" is used to indicate a small device that can be used to complete or make a circuit. This can be as complicated as a micro-processor or as simple as a large resistor network/array, single transistor or even just a diode.

v - ConcaveConcave refers to pins that have a hollowed outer pin surface.

x - Connector/Axial/ConvexAs a starting letter x indicates a connector.

Axial - In the second position x indicates that the package has one pin protruding axially from each end of the package. In any other position x refers to pins of a chip array that extend beyond the package body (Convex).

Suffix Letters

a - AlternateAs you work with the letters it might happen that you just cannot decide how to indicate one package is different than another. A picture works often if the library you are working with supports this but for a name you might just resolve to include an a suffix to indicate this is an alternate.

b - BrightThis would indicate a package that is brighter than the expected brightness. One example would be a resistor array in a small outline package or Zentroid package udg8_127p60x16 that is manufactured in white plastic.

d - DarkAs you might expect a package that is unusually dark. Zentroid often uses the d with black tantalum capacitors.

h - Heat SinkThe existence of a thermal pad may confuse optical centering methods so the option to indicate this is to use the letter h. Should the normal condition of the package include a thermal pad use an n before the h to negate it.

m - Mount PinsUsed often with connectors. m indicates that the package has extra pins that are used primarily to help hold the package in place.

n - NoUsed to negate the meaning of the other suffix letters. nh for example would indicate no Heat Sink/Thermal Pad.

p - PlugThis is the male counterpart of a connector pair. The outermost form of the plug will be received within the outermost form of the receptacle. Retaining clips are not taken into this consideration.

r - ReceptacleThis is the female counterpart of a connector pair. The outermost form of the receptacle will receive the plugs form inside. Retaining clips are not taken into this consideration.

s - SidewaysSideways is used to indicate that the packages functional direction is to the side. This can be a connector with the attached connector coming in from the side, an led emitting to the side, a switch that will be pushed from the side, etc.

soc - SocketSockets are holders that make components removable from the printed circuit board. Note that the prefix used for sockets is that of the component.

t - ThinIn most cases Zentroid uses the overall width of packages in the name. If the Pin over Pin width is the same as an identically named package but the housing width of the package is less you can use t to indicate this.

w - WideWide is used in the same respect as thin except the housing width of the package would then be more than the identically named package.

x - Missingx was used originally by Zentroid only to indicate missing pins from a T-Form pin group. It is now used similar to the a for alternate but indicates more importantly that the difference is in respect to that of something missing, not necessarily only a pin.

Letters Within The Zentroid SMD Naming Convention

c - Collapsing/ColumnsUsed in conjunction with Ball Array packages. Collapsing means that the balls will collapse. Following the pitch entry in the name is a value followed by a c. In this position c means columns. Knowing the total number of pins and the number of columns almost 100% infers the number of rows so an entry for rows is not used.

n - Non-collapsingAs expected, the balls of a Ball Array that do not collapse.

p - PitchThe center to center measurement of the pin end spacing. In a row of unevenly spaced pin ends this measurement will be the smallest spacing measured.

sp - Staggered PitchThis refers to the relationship of the pin locations between 2 rows of pins. The locations of one of the pin groups will be vertically or horizontally between the locations of the other group. The pins may be on the same side or different sides of the package. You can see an example of this in Zentroid's Connector page.

up - Uneven PitchUneven pitch simply indicates that the pin spacing differs. This can be due to a missing pin, shifted pins or random spacing of pins.

x - Height followsAfter the x will be given the overall height of the package in tenths of millimeter.