Question: Why did the IPC change the barrel fill requirement for Class 2 in J-STD-001 Revision F? Revision E allowed 50% when there was a thermal plane. Now, Rev. F states 75% regardless of thermal plane. It all depends on how many leads the component has, with 14 being the magic number.
Could you shed some light on “WHY” the IPC changed the standard?
Answer: This was changed when a proposal was submitted by HP for plated hole filling with components with more than 14 leads, which had connections to inner layers of the circuit board. During the document editing process, the existing piece of information for Class 2 and less than 14 leads was left out of the document and never caught during the editing process. It was a MISTAKE.
To that end the 001 and 610 IPC committees are creating amendments to J-STD-001 and IPC-610 which will be release within the next month clearing all this up.