Julie,
We had this problem 5 years ago when we installed our Shadow line.
Believe it or not with the help of our chemical supplier and FSL, the
equipment builder, it was narrowed down to the angle of the air knives.
Also, if you have a burr and "crap" is trapped underneath this will give
you problems. I would enlist the help of your chemical supplier and
whoever built your equipment. If I can be of further assistance please
feel free to call me at 505.345.5591 ext. 3064.
Good Luck,
Rick Howieson
General Technology Corp.
www.gt-corp.com
>-----Original Message-----
>From: Julie Dixon [SMTP:[log in to unmask]]
>Sent: Tuesday, December 21, 1999 2:58 PM
>To: [log in to unmask]
>Subject: [TN] Ring Voids
>
>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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