Ask Helena & Leo

Question: We have a couple of questions regarding the new IPC-A-610 Revision F document and vertical fill.

They are:

1. . Acceptable – Class 1,23: Minimum vertical fill of 50% or 1.2 mm for components with 14 or more leads. What is the importance of 14 or more leads? Does the vertical fill depend more on the thermal layers and not the number of leads?
2. 2. Defect – Class 2: Revision ‘E” also had the paragraphs on PTH connected to thermal or conductor layers that act as thermal heat sinks. We have several projects that have the heavy thermal connections on several layers where, when using pre-heaters and two soldering irons, we still cannot get the solder to flow 75%. Any suggestions?

Answer: This is a question being asked a lot since the document was released last October. The problem was exposed at the last IPC meeting when we reviewed the physical document. The section which is currently in the document was work presented by HP on multileaded components with more than 14 leads, (i.e.) ICs, Connectors, Headers, etc.

The segment of the document that covers the section for less than 14 leads and Class 2 requirements for 50% hole fill due to inner layer heat sinking was left out of the documents, and now in this revision of both 610 and 001, that particular section is missing. The Committees of both 610 and 001 are working to create an amendment to add the language back into the documents. It was a mistake that is not in the documents and we are telling everyone of this omission and telling them to use the older revision for this particular segment of the specification.

I would suggest keeping track of the IPC activities on this topic, which can be monitored at http://www.ipc.org/CommitteeDetail.aspx?Committee=5-22A and http://www.ipc.org/CommitteeDetail.aspx?Committee=7-31B