TMCM CONFORMAL COATING MRB  MINUTES

                    Wednesday November 3,  2004

 

 

Prepared By:  Richard Gobin

 

Date:              Nov. 8, 2004

 

Subject:          LAT-DS-00898/899 TMCM’s  Humiseal 1A20 conformal coating workmanship issues.

 

SPEC:             Dwg. LAT-DS-00898/899 Rev 11, note 8.

 

Subsystem:     Tracker

 

Drawing:        LAT-DS-00898/899 REV. 10 & 11.

 

 

Attendees:     SLAC:  Dr. Robert Johnson, Dave Rich, Darren Marsh, Tom Himel, Richard Gobin, Dianne Graham.

 

NASA:  Jim Lohr, Bernie Graff, Tracy Shepherd.

 

 

Summary:       Have done a very careful inspection of ~ 250 TMCM’s @ SLAC.  Virtually all have some problems. All are documented in a spreadsheet maintain by LAT QA & NCR’s.

 

Ref:                NCR’s:  00154, 00182, 00196, 00201, And 00202

 

       About 50 TMCM’s have virtually no CC on the sides of many components. Most have no CC near the encapsulant including on a few solder pads.

       Most have CC lifting on the top or sides of some components.  Locations are documented.

       A few have a visible contaminant.

       A few have small gold nodules in the grounding screw holes.

       A few have CC problems near the screw holes

       Many have CC in the connectors.

       Production at Teledyne is shut down while process changes are devised to reduce these problems on future boards

 

Have thermal cycled 5 board 200 times. Lifting did not get worse.

Have vacuum cycled 4 boards 3 times. Lifting did not get worse.

 

 

 

 

 

 

ACTION PLAN proposed by GLAST SLAC:

       No CC on the sides of many components and near the encapsulant.

        Fix by cleaning and applying coating with a brush.

       CC lifting.

        Leave as is

       Visible contaminant.

        Judge by size and location whether to leave or remove and recoat

       A few have small gold nodules in the grounding screw holes.

        Fix by scraping off.  This will leave a non-gold plated spot in the hole, but it is the head of the screw that makes the electrical contact.

       A few have CC problems near the screw holes

        Fix because they are few and it is easy.

       Many have CC in the connectors.

        Fix by carefully removing loose CC.

 

 

Conclusions: 

                        MRB agreed to all items in action plan.

 

 Action Items:

 

LAT QA to identify all TMCM’s SLAC bldg. 33 which met the USE AS IS criteria for lifting of the CC.

 

LAT QA to update all impacted open NCR’s to reflect the MRB decision to USE AS IS.

 

LAT QA to assure all rework for CC touch up meets the released rework procedure LAT-PS-05038-01.

 

LAT QA has initiated removal of CC @ the J1/J2 junction. Jerome Lepulu is the trained dedicated technician for removal of the CC on the nano connectors. LAT QA continues to monitor rework daily.

 

LAT QA has instructed inspectors to measure all gold nodules found in the PTH’s. If nodules are deemed “large” (>0.010”), these are to be removed prior to acceptance.

 

Respectfully,

Richard Gobin

GLAST QE