Many schematics will incorporate new parts and these present the greatest challenge to design processing. New parts require that a job “Place Holder” be created that can be used to collect decal, package, description and a full company part number. Index Designs
designed its parallel BOM such that components without part numbers are maintained and design information can be collected through the process. The state of each BOM line item is identified using color.

The logic by which BOM items are color-coded depends on the view selected by the user. Having the data to drive a PCB design process does not imply the data exists to drive the assembly process. Jobs from external customers might be annotated to where they can be assembled but not to the degree required to drive PCB assembly.

7. Additional Functions
Probably the most unique and useful piece of code in the Index Designs library is a custom electronic component indexing and lookup engine. This engine uses several techniques to reduce a BOM line item description to an in house part number. A very common task is to convert microfarads to Pico farads. Line items such a 0.001uf are matched to 1000pf. The indexer is driven from any data source that contains a Company Part number and a description. Additional code was required to synchronize indexer tables with a company
database in a time efficient manner.

The second major requirement was a tool that allows a complete machine setup to be saved, recalled and changed. During the course of preparing a job for assembly it is common to get “Changes”. Either an existing part must change or a new part must be added. In either case existing trays might already be stuffed and the new or changed component must be worked into the job setup.

The third major function that Index Designs has recently added is a Package Wizard. The current scheme required two PowerPCB libraries, one for land patterns and another that identifies package shapes and contact areas. A Package Wizard has been added that allows parts definitions to be constructed outside of the PowerPCB library editor. These package definitions are applied against a IPC-7351 rule sets and generates PowerPCB land patterns. This new scheme reduces the number of libraries and allows quick and accurate
generation of land patterns.

8. Summary
While Index Designs has developed a significant amount of code to automate this process (42K lines in Delphi at last count) much of this has been added to expedite the assembly of external jobs. If only in house schematics and PCB designs are to be assembled then
several processes can be simplified.

• Only rotational data is required to map from PowerPCB rotation to machine rotation. A very simple script can adjust the CAM outputs.

• No search engine is required if schematic library attributes are used to store rotation and
part feeder information. The search engine is a powerful technique but most engineering
groups already live with extensive library attributes.

• Trays are very useful for feeding all types of loose parts but the code to “Compile” a BOM
into tray configurations is very complex. Strips of tape placed on pin trays might be able to
simplify assembly machine setup. Much of what is possible depends on assembly machine
software.

The current scheme at Index Designs has reduced part setup to 1 hour for two medium sized boards with remaining machine setup at about 30 minutes. Much of this setup is preformed “Off Line” from the assembly machine and does not affect other jobs. Stencil setup and tear down requires another 30 minutes. Hand placing of these boards is 4 to 6 hours each.

The remaining area where costs can be reduced is in stencil costs. Stencil costs are currently about $150 per side and there are shipping costs and delays. Our plan is to laser cut stencils using data from the new Package Wizard. Quality assembly starts with getting the correct amount of solder paste in the correct position. Lead contact areas define the correct position of paste. Solder paste files that are received from customers tend to be based on land patterns and for from optimal. If Index Designs can generate custom laser cut stencils from package data it should be able to improve the quality of the assembled product and reduce costs.