The IPC-A-610D standard defines solder joint acceptability through visual criteria like wetting angles and vertical fill percentage rather than "solid content". While IPC-A-610 focuses on visual inspection, requirements for material solid content are managed under the IPC J-STD-001 standard. Read more about the differences at electronicsgroup.co.uk . IPC-A-610 vs IPC J-STD-001: What is the Difference?