Issue link: https://iconnect007.uberflip.com/i/594816
November 2015 • SMT Magazine 87 method for deriving the type assignments, and the connection of those assignments to the rules themselves, can be released via software updates without disturbing the library content that is at the root of the process. To illustrate the application of a DFA rule in the context of the type-assignments, Figure 8a shows a minimum heel-distance rule for com- ponents with lead forms of type "c-bend-wrap." The rule calls for a minimum spacing of 5 mils, with 9 mils being the target for best yield. Fig- ure 8b then shows the result of applying this specific rule to the relevant components; in this case, the minimum heel distance is actually negative, thus calling for either an engineer- ing change to the land pattern, of a change of components supplier on the master parts list, or maybe both. Third requirement The third element of the portable DFA solu- tion is a documented language of rules that can be transferred between manufacturer and de- signer for application as early as possible in the STreAmLINING PCb ASSembLy AND TeST NPI WITH SHAreD ComPoNeNT LIbrArIeS arTIcLe figure 7: rules-based classification of package and lead form for Dfa rules management. figure 8a: a Dfa rule for minimum heel distance for a specific class of component.