Why bga reballing and why it is important

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What is BGA Reballing and
Why it needs to be done
www.solder.net

BGA Reballing
• Handling of Parts
• Data Sheets
• Tools
• Process
• Inspection
• “Gotchas”
• Marking
• Bakeout and Drypack
• Profiling

Why Devices Get Reballed

Availability

Alloy conversion

Rework
Why BGA Reballing is
important

Handling of Parts
 Work areas must be kept clean and neat in
order to prevent contamination of the work
area
 Stacking of devices should be avoided to
prevent physical damage
 Trays for handling

 Components should be handled by the edges or
with proper ESD-safe tooling (JSTD-001)
 When not being worked on, sensitive components
must be enclosed in shielded bags or boxes.
 Whenever handling an area array device the
operator must be properly grounded
Handling of Parts-ESD

 Devices should be handled at properly
designated work areas only
 Designated ESD safe work areas must
be checked periodically to ensure their
continued safety from ESD
 Static dissipation of work surfaces
 Static dissipation of floor surfaces
 Designated work areas must be kept
free of static generating materials such
as styrofoam, vinyl, plastic, fabrics or
any other static generating materials
Handling of Parts-ESD

Handling of Parts-MSD
 Awareness of the MSD level
 Risk of “popcorning” or part delamination
 Logging system for control
 Dry box for control of moisture levels of
parts for reballing/rework
 (Do not open the doors too frequently and
/ or for extended periods of time)
 Familiarity and knowledge of
IPC/JEDEC J-STD-033 (handling) J-STD-
020 (parts classification)

Data Sheets
Drive the design of the fixture, stencils and preforms

Tools for Reballing-
Inspection

Inspection
 Excessive graininess
 Incomplete reflow
 Poor wetting
 Balls with pits, voids, indentations,
gouges and other depressions
exceeding 20% of ball diameter
 Burrs exceeding 10% of ball diameter
 Balls with peeling, flaking or blistering
See IPC 7095

XRAY Inspection

High volume-several thousand pieces
Reball Process

Fixtures and/or stainless stencils
Reball Process
Moderate volume <2K pieces

Non contact deballing
Photo Courtesy of VJ Electronix

Reball Process
Semi-automated process

Pick and Place solder ball pre-form
Pre-form
Reball Process

Reflow spheres onto substrate
Reball Process

Reball Process
Low Volume 1-several hundred
Cut in-house for fastest
delivery

Reball Process
“Peel Away Preform”

Ability to
reball down
to 0.15mm
pitch, 4 mil
ball size
Reball Process
“Peel Away Preform”

Marking
Identify parts which have been
reballed
Color
dots
used
by
some

Bake Out + Dry Pack
Used when shipping reballed
devices

 Thermal gradient 2-3°C
 Soak temperature (board) 150°C
 Short preheat (as needed)
 Reflow temp 210-220°C (liquidus 183°)
 Reflow time 45-90 seconds (for lead free), 30-60 seconds (for
Sn63Pb37)
Proper Thermal Profiling

Lead-Free BGA Reballing
Concerns
 Die exposure to multiple heat cycles
(can be overcome with process)
 Cross-contamination of materials
(controlled by process)

For reballing projects:
Call 847-797-9250
or send mail to
info@solder.net
www.solder.net

Why bga reballing and why it is important

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