Adding, modifying and deleting packages

The application shows a single package at a time. On the top row, you will find the navigation buttons (browse buttons), as well as menu and search buttons. Below that, the package information is split in three sections.

Figure 1: user-interface, main view

The first section gives the generic package information: its name (or identification), its body size, number of pins, pitch between the pins, termination style (shape of the leads), and other characteristics.

The second section lists variants of the same “common shape” for the package. The variant adds the height of the package, the standard it conforms to (if any) and the presence of an exposed pad (or “thermal pad”) to the generic information. See topic Common names & variants for the distinction between a generic package and a variant.

The third section gives detailed information about the footprint for the package: the shape and size of the pads, and the positions of these pads. As an aside, Packages does not generate footprints for any EDA program —that is not its goal. However, due to the open format of the output file, a third-party script can use the detailed information on the package and pads to generate these footprints.

Depending on the package, not all data may be relevant. However, the top section (of the user-interface, see Figure 1) should always be completed.

Names, description

A package may have more than one name —this is covered in detail in the topic Common names & variants. The names that refer to the generic “flat view” shape of the package, should be listed as names in the top section. Other applications can use these aliases to look up package information in the course of exchanging data: different programs used in electronics production may use different names for the same package. Applications can also use the aliases to translate all packages being entered into the system to a preferred naming convention.

In the case of “chip” packages, like 0603 and 0805, we recommend to include both the “imperial” name and the “metric” name for the package (in this case 1508 and 2012 respectively). As explained in Metric versus Imperial, conflicts arise for the smaller packages: for example, 0603 is a valid package label in both imperial and metric —but pointing to two very different packages. Since Packages does not allow for naming conflicts, our recommendation is to add an “M” suffix to the metric label: the equivalent for 0603 is 1508M, and 0805 is 2012M.

In general, we also suggest to put the preferred name(s) first in the list of names. When an application translates package names into a preferred naming convention, it typically picks the first “preferred name” that matches the chosen naming convention.

The description is optional, and contains general purpose text. The description is included in the search function, so you can use the description to include search terms that are not covered by the other fields.

Characteristics

For SMD type packages (the focus of the Packages application and data file), the termination field is an important parameter. For optical alignment, pick-&-place machines need to know at what elevation to scan the (body of the) component, and that depends on the lead shape. Therefore, packages that are identical apart from their termination style, must be entered as separate packages. For example, SOD123 and SOD123F have gull-wing and lug-lead terminations respectively, and they are therefore separate packages —not variants.

The fields for the pin count and pitch are fairly self-explanatory (see also topic Pitch and spans for the pitch dimension). An exposed-pad (or thermal pad) is seen as an attribute of a package, and it is typically not included in the pin count.

The tape packaging orientation is standardized for common parts (see chapter Normal orientations). For connectors or exotic packages, the tape orientation can be selected here. Tape packaging orientation is relevant only for components package is tape (on reel); for packages too big for tape packaging, leave this field at zero. Again, see chapter Normal orientations for details.

The relevance of the “polarized” field is that packages for polarized components are regularly oriented differently in tape packaging than those for non-polarized parts.

Body size, lead-to-lead size

Body size and lead-to-lead size are also inherent characteristics of a package. These sizes allow for a tolerance, however (this tolerance can be looked up in the specifications of the respective packages). See topic Package dimensions and outlines for details on the various “size” specifications of a package.

If a package does not have pins (termination is either “endcap” or “no-lead”, the lead-to-lead size does not need to be filled in (it is by consequence identical to the body size).

References

If a package is standardized by one or more normative institutions, the name of the standard and the name of the institution can be added here. These fields are informational; if your company uses internal standards, these can be added here as well.

Related packages

If a package is related to a different package, the name of the other package can be added here. For example, the diode packages SOD123 and SOD123F are identical except for their pin shape (gull-wing versus lug-lead). It then makes sense to mark these packages as related to each other.

Variants

The middle section in the user interface is for the variants of the generic package. The generic package portrays a flattened view. For a long time, EDA programs needed no more that this representation. For assembly of the PCB, and for mechanical design (e.g. design of the enclosure), the height of the package also becomes an important parameter (and it is quite common that a generic package exists in different heights). This is why the details of various variants can be entered in a table. See the topic Common names & variants for background information.

For example, an LQFP package and an TQFP package share all parameters (and they share it with the generic QFP package), except that LQFP is about 1.5 mm thick and TQFP about 1.0 mm.

Each variant must have a unique name, and the name of a variant may not conflict with any of the aliases for the generic package either. Names for variants may follow a standard or an ad-hoc convention —see also topic Package naming standards. If it is a standardized convention, you can indicate that convention on the row too. Doing so enables applications to translate between naming conventions.

For the “flat view” dimensions, Packages stores the nominal size and a tolerance from that nominal size. For the height, it uses a range: minimum height to maximum height. The motivation is that package standards also specify the height as a range; IPC-7351 only records a maximum height in its naming convention.

Footprint

The bottom section of Figure 1 has design parameters for the footprint. A single package may have multiple footprints. For example, the IPC-7351 standard defines footprints for Least, Nominal and Most spacing between components (less spacing allows for higher density). Some packages may also define an adjusted footprint for wave soldering (as opposed to reflow).

The majority of footprints use a single pad shape & size for most (or all) of the pins. Packages splits the pad shapes from the pad positions for a package. Thus, you often need to add only one or two pad shapes, even for packages with a high pin count.

In the pad shape specification, you can furthermore mark a pad as “exposed pad” (also called a thermal pad). A pad marked as such is then only valid for those variants that are also marked as having an exposed pad (in the “variants” section of the user interface).

For example, for a HSOIC8 package (8-pin SOIC with 1.27 mm pitch and an exposed-pad):

The exposed pad is typically not included in the pin count (in the package characteristics, top section of the user interface).