Select the Case command from the upper right quadrant. The lower right quadrant is activated. You can now vary the length, width, thickness, inside length, inside width, and inside thickness of the case using the techniques you learned in Section 6.3.4.4.

Editing the Case parameters

• Select the Parameters button to the right of the case command. If you entered "plastic" in the Material Type field in the Constraints window in 6.2.4.1, an Editing Plastic Base window appears. If you entered "ceramic" or "metal," an Editing Hermetic Base window appears (see Figure 53). If you entered "BGA" an editing BGA window appears. Their fields are defined below.
• Edit the fields if you wish. Select Accept to accept, Cancel to cancel. You return to the Package screen.

Definitions for Case Window

The parameter windows defining plastic, hermetic, and BGA package are different. The differences are noted below. In addition, if you are designing a package that has curved corners, the fields corner radius (in) and corner radius (out) appear in the Hermetic window and are defined at the end of the Hermetic parameter windows definitions. Some of the terms below are defined further in the Glossary in Appendix B. There is also a difference between a Modular and a Uniwall case. A modular case has attachments between the header and the wall, which may be constructed of different materials. Uniwall cases are made of single, solid material and are often milled or cast. See the figures in Appendix C for further clarification of the differences between these types of hermetic packages, and the attributes which are unique to each.

Hermetic package windows

An option is available to create internal walls in a ceramic hybrid module in order to partition the module into discrete areas having independent thermal characteristics. Select the Regions hot key to activate this option. A cursor will appear in an enlarged display of the top view of the package. Click the right mouse button at the top left corner of the wall you wish to insert. Then drag the mouse to the lower right corner of the wall. A wall of the appropriate length and thickness will be displayed. Next you will be prompted to choose a material for the wall from a picklist. Select the desired material and then select the ACCEPT hot key to save your choice.

Wall material: The material composing the walls of the package. This is a picklist field. You can view the material properties of the wall material by selecting the Properties button. A Material Properties window appears. The fields in the window are defined in the Glossary. If the material you want is not in the picklist, add it via the Materials Library option.

Header material: The material composing the base of the package. The header does not include the lid. This is a picklist field. You can view the material properties of the header material by selecting the Properties button. A Material Properties window appears. The fields in the window are defined in the Glossary.

Header Attach material: This is a picklist field. Notice the Property button calls a Material Properties window that is more extensive than the one for wall and header material. Its fields are defined in the Glossary.

Header Attach thickness: The thickness, in mils, of the material used to attach the header to the wall. This is an entry field. The range for this field is 0 to 100 mils.

Leak Rate: The leakage rate of a hermetically sealed package. The leakage rate is defined in terms of cubic centimeters of helium per second at a pressure differential of one atmosphere. This is a picklist field. You can select one of three values: 1.0E-6, 1.0E-7, or 1.0E-8.

Matr. W/rad. Contaminant: The non-radioactive material that will contain radioactive containment. This is a picklist field. You can view the material properties of the header material by selecting the Properties button. A Material Properties window appears. The fields in the window are defined in the Glossary.

Radioactive contaminant: The radioactive contaminant itself. Refer to the naturally occurring radioactive contaminants introduced during package sealing. This is a picklist field. (See Figure 55).

Concentration of contaminant: The amount of radioactive contaminant in parts per million of the package element with contaminant. This is an entry field. The range for this field is 0.00E+00 to 1.00E+10 ppm of the non-radioactive material

Corner radius (in): Inner corner radius of the case. This is an entry field. The range for this field is 0 to 1,000 mils.

Corner radius (out): Outer corner radius of the case. This is an entry field. The range for this field is 0 to 1,000 mils.

Plastic package windows

A window appears with the Matr. W/rad. contaminant, concentration of contaminant, and Radioactive contaminant fields as defined above, as well as the fields defined below.

Plastic package matr.: The material the package is made of. This is a picklist field. You can view the material properties of the plastic by selecting the Properties button. A Material Properties window appears. The fields in the window are defined in the Glossary.

Permeation constant: the rate at which gases diffuse or pass through the plastic package material. This is an entry field. The range for this field is 0.00+00 to 1.00E+00.

Pressure ratio (inside/outside): The ratio of the atmosphere inside the package to the pressure outside the package. This is an entry field.

Length of edge to electrolyte: The length, in mils, from the edge of the package to the electrolyte. This is an entry field. The range for this field is 1 to 100 mils.
 

BGA package windows:

Mounting Platform - the printed wiring board – like metal coated laminate material on which the semiconductor device is mounted.