1. Logic and Parts List
The design engineer provides at least the following information
to the packaging designer, preferably in the form of a written document,
signed, and dated:
• Parts list
• Preferred component placement, including circuit partitioning
for each MIB for double-sided modules
• Component power dissipation
• Definition of critical lines with respect to current, voltage
drop, length, frequency, other
All changes should be red-lined, signed, and dated.
2. Device/Symbol in CAD Library
If the device is not already in the CAD library, it is entered
at this time. The CAD library includes information such as pinouts, loading,
package type, and thermal analysis data.
3. Logic Diagrams/CAD Database Generation
The formalized logic diagrams are generated and the CAD database
is created for use in automatic placement and routing.
4. Logic Diagrams/CAD Database Verification
The CAD-generated schematic and database are verified against
the circuit designer's original schematic.
5. Manual Placement
After verification of the CAD schematic and database, a
preliminary placement of the devices is normally produced to determine whether
or not all the devices will fit on the board.
6. Initial Thermal Analysis
If the predicted power dissipation for the MIB assembly exceeds
a moderate level, an initial thermal analysis is usually performed to identify
thermal problems and to influence component placement at the earliest date. A
loading analysis may also be performed to discover any loading problems which
may require additional buffers or other devices.
7. Preliminary Design Review
At this point, a Preliminary Design Review is held on the MIB
assembly. The information reviewed should include at least the following:
power dissipation calculations, initial thermal analysis (if required),
preliminary device layout, logic diagram, and parts list.
8. Preliminary Design Changes
Any changes made at the Preliminary Design Review are
incorporated in the logic and database. Changes affecting the original
documentation should be signed and dated. No further design activity should
proceed without the circuit designer's approval of the preliminary design.
9. Frame Design
If the MIB assembly has a unique heat sink or other mechanical
features, this design action is started at this time.
10. Preliminary Thermal Analysis
A preliminary thermal analysis is performed for the entire MIB
assembly based on component placement, power dissipation, thermal path, and
the operational time profile and duty cycle.
11. Preliminary Reliability Analysis
A preliminary reliability analysis is performed based on the IC
junction temperatures derived from the thermal analysis.
12. Performance Specification
The design engineer generates a performance specification for
the MIB assembly, including such information as timing, bus operation,
on-board test capabilities, fault detection/fault localization, and other
pertinent data necessary to define the function and performance of the MIB
13. Product Documentation
The product documentation necessary for release which provides
the "paper trail" to the next lower or higher document is prepared at this
14. Preliminary Routing
Automatic routing of each MIB is performed at this time using
the placement determined previously. Input/output pins are assigned and
interconnects between multiple boards in the assembly are defined.
15. Critical Design Review
A Critical Design Review is held after completion of routing.
The performance specification, preliminary thermal and reliability analysis
results, placement, logic diagram, and product documentation are supplied.
16. Critical Design Changes
Any changes made in the Critical Design Review are incorporated
in the appropriate tasks.
17. Final Routing
The final cleanup of the routing is performed and a net-list is
18. Final Thermal Analysis
Using the final placement, the thermal analysis is reviewed and
19. Final Reliability Analysis
The reliability analysis is reviewed and updated based on the
junction temperatures from the final thermal analysis.
20. Product Documentation Update
The results of the analyses, the finalized performance
specification, I/O pin assignments, and interconnections are incorporated in
the final product documentation.
21. Artwork and Manufacturing Documentation
Parallel to the product documentation update effort, the artwork
and manufacturing documentation are generated.
22. Release Review
The artwork and manufacturing documentation are released to
Manufacturing at the Release Review.
23. Test Requirements Specification
The test requirements specification is released to Manufacturing
by Test Engineering for MIB assembly test in production.