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BGA Rework

I.I. Why ReworkWhy Rework

II.II. Scope of Material CoveredScope of Material Covered

III.III. BGA Rework ProcessBGA Rework ProcessA.A. RemovalRemoval

B.B. Site DressingSite Dressing

C.C. PlacementPlacement

D.D. ReflowReflow

E.E. CleaningCleaning

F.F. InspectionInspection

IV.IV. MaterialsMaterials


CleaningObjective remove soils that will impact product reliability of a PCB based on the end use environment and/or provide for surface that will accept a subsequent coating.

BGA Rework-the process


CleaningObjective remove soils



Inspection-VisualObjective assure that the rework process performed meets the inspection criteria applicable



Inspection - endoscope



BGA Rework-the processInspection- Transmissive X-ray


Inspection- Laminographic X-ray or CT scanning



BGA XRAY inspection-3Dhttp://www.youtube.com/watch?v=7AQzccfwSsQ



Inspection- Inspection Criteria•May involve visual assessment only (Table 1-2 )•Process validation can be used in lieu of X-Ray/Visual inspection provided objective evidence is available•Outside rows through visual inspection when practical•Alignment in both X and Y w/corner markers on PCB (if present)



S8-11

8.3.12 Surface Mount Area Array (cont.)

Feature Clause Classes 1,2 and 3

Alignment 8.3.12.1 No violation of minimum electrical clearance

Solder Ball Spacing

8.3.12.2 No violation of minimum electrical clearance

Soldering Connections

8.3.12.3 No bridging. Solder balls contact and wet to the land forming connection of right shape

Voids 8.3.12.4 25% or less voiding of any ball in the xray image area

Underfill or staking material

8.3.12.5 Present and completely cured

Inspection- Inspection Criteria-IPC-A-610 (collapsing balls)


Inspection- Inspection CriteriaTarget 1,2,3 -Uniform size and shapeAcceptable 1,2,3-No bridging, continuous ellipticalProcess Indicator 1,2,3 –Non uniform size, color, shapeDefect 1,2,3- solder bridging, waste showing paste did not flow together, fractured solder connection, no connect between ball and solder



Planar Microvoids (<1-2 mils)

Macrovoids



Microvia Voids



BGA Rework-MaterialsFlux

• RoHS Issues• Higher processing temperatures• Longer time above liquidus


BGA Rework-MaterialsSolder

RoHS Issues•Lower wettability•Higher reflow temperatures•Specialty rheology formulations for dipping

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BGA Cleaning and Inspection