Dear Net,

Please shoot me now. I ran a test to incorporate all your theories that
applied.
We needed 6 good panels for the rerun. They were our golden boards. Ran with
my 8 test panels.

Drill- First 3 stack had probs., shallow holes, didn't remove, redrilled, oK.
       The rest drilled oK.
We deburred, high pressure sprayed, Inspected. Drilling looked good except on
1
panel which had to be hand sanded. We clipped the corner.

DML- All 14 in one load. Ohm Readings good. Insp'd nothing to see after DML
and
we saw nothing.

Lamination- Thursday pm scrubbed and laminated 7 panels. 2 panels were shot,
developed and had registration probs. We held.
Next AM we scrubbed and laminated 2 more panels. We exposed and
developed the 5 + 1 panels. (1 held)
We scrubbed 5 more panels, +1 ^, + 2 needing rework from Thurs= 8 test panels.
Processed 8 as follows below.

DEFECT: Ring voids just under knee of hole. Knee appears intact.

      THEORY #1: Dry film entrapment due to lamination on a board w/wet holes.
    TEST #1: Identify 2 panels with 1 notch under coupon.
             Step A- Wet laminate 2 panels
             Step B-  Minimize developing. Find breakpoint; process slightly
faster.
             Step C- Inspect post development. Note any abnormalities by Test
# ID
             Step D- Inspect post plate. Note findings by Test #ID.
      THEORY #2: Rework of dry film lamination is removing DML.
    TEST #2: Identify 2 panels with 2 notches under coupon.
                Step A- Strip dry film from panels.
                Step B- Scrub under 3.
                Step C- Laminate dry.
                Step D- Inspect post plate. Note findings by Test #ID.
      THEORY #3: Combination of #1 & #2.
    TEST #3: Identify 2 panels with 3 notches under coupon.
                Step A- Strip dry film from panels.
                Step B- Scrub under 3.
                Step C- Laminate wet.
                Step D- Inspect post plate. Note findings by Test #ID.
      THEORY #4: Tin etch resist too thin.
    TEST #4: Identify 2 panels with 4 notches under coupon.
                Step A- Remove panels from ends of tin tank after 5
minutes.(1/2 X) ti
                Step B- Inspect post plate. Note findings by Test #ID.
                Step C- Scrub aggressively after dry film strip.
                Step D- Inspect tin post dry film strip. Note findings by
Test #ID.
                Step D- Etch both panels; Inspect post etch.
                Step E- Rework panels through etch; Inspect post etch rework.

Post drill, dml, scrub, development, copper, tin- No defects found.
Post etch, 8 abused boards looked good. 6 not insp'd.

Post tin strip. Help me here- all 6 golden boards were scrap due to peppered
knee
voids, both sides of the panel. Some very difficult to see, all same
orientation. Some
major and wipe out the pad. ~10-25% holes with defect. The 8 abused boards,
includ
ing the clipped panel were fine. Zero defects.
???

Julie

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