x-ray inspection bga glenbrook technologies

8/13/2019 X-Ray Inspection BGA Glenbrook Technologies

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Nokia Internal Use OnlyNokia Internal Use Only

Basic Principles ofX-Ray Inspection for BGAs


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Nokia Internal Use Only

Increased Use of BGAs

Ball Grid Arrays - array of solderball connections underneathcomponent

Provides many advantages overleaded components

Reduced component size

Increased I/O count

Smaller footprint

Increased performancecharacteristics


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The Problem with BGAs

How to verify a solder bondthat cannot be observed?

Hidden joints - touch up not

possible Only way to test integrity of

joints Electrical test

Look Under/Video Scope

X-Ray


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How X-Rays Work

image

Presence or Absence of Material

wedge objectx-rays x-rays detector

imagedetectorlow density

high density material

x-raysx-rays

Differences in Material Density


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X-ray tube generatesx-ray energy

X-rays absorbed where

density exists in

sample - remaining

x-rays pass through

& strike the detector

Detector converts

x-rays to visible light,

video camera sends

image to processor

Image Processor

enhances x-ray

images for high-

resolution viewing

The image you see

How an X-Ray System Works


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Solder Connections Under X-Ray

Analysis

Main characteristic:

uniformity of the

connections

If X-ray shows all

connections uniformly

circular & equal in area

- good indication ofcomplete/proper reflow


7/25Nokia Internal Use Only

Nearly all Defects have Signatures

Bridging, missing balls, largevoids obvious

Other defects subtle

Look for pattern in distortion ofsize/shape of bond image

Operator learns to identify

defect signatures, processproblems and quickly make

adjustments



May be due to excess

paste or flux

Improper reworkimplicated

Solder splattering due

to poor reflowconditions

Defects Identified by X-Ray: Bridging

Look Under Scope Image



Misregistration

Result of errors in component placement

Possible issues with solder mask alignment



Insufficient Reflow

More difficult to spot

If package misplaced,ball shape may beelliptical (easier toidentify)

Bond distribution not

consistent



Can occur in

manufacturing process

Usually due tomishandling

Missing Balls



Cold Solder

More difficult to identify

Signified by jagged

irregular edge around

the perimeter of the

solder ball



Solder Voids

Result of moisture in

BGA packagemust be

thoroughly baked out

Problems with solder

paste

Huge issue with lead-

free solder



Voids a process indicator,

not defect unless excessively

large

Motorola Study - balls that

contain voids up to 24%

more reliable than those

without voids!

Solder Voids



At 70 kV

Associated with camera usedin many X-ray systems

As voltage increased, void

artificially appears to expand(bloom)At 50 kV

Makes void appear larger

than it really is Glenbrook systems not

subject to voltage blooming

Solder Voids & Voltage Blooming



Potato Chipping/Popcorning

BGAs outside edge lifts

up from a pad

Center joints squashed

due to compressionunder die area

Caused by moisture in

BGA or excessivetopside temperature

Normal

Potato Chipping



Note distortion/ warpage of

ball bonds lower right

corner

View through Look-Under

scope. Note package

peeling away from solderball

Potato Chipping/Popcorning



Opens (require angled viewing)

Ball smaller thanadjacent balls

Pad shadow seen below

indicating no contactbetween ball & pad

Note two unattachedspherical shapes unlikeoval shapes adjacent to it indicate no contact

between pad & solder ball



RTX-113HV X-Ray Inspection System

Features powerful 80 kVX-ray tube

GTI-5000 image processor

with auto-BGA analysissoftware

Sees through densemultilayer PCBs & metal

capped BGAs

Variable Angle Viewingallows for 45 degree viewing



GTI-5000 Image Processing Software

Provides analysis of BGA

defects: bridging, voids,

missing balls

Measures BGA ball size,

ball roundness & void size

Software identifies any ball outside of set tolerance

Includes CPU, Frame Grabber, Software, Color

Monitor



Variable Angled Viewing

Allows for 45 degree viewing

X-Ray source is rotated

Allows inspection for fullrange of hidden BGA defects: Missing or mis-registered

solder spheres

Misalignments Gross solder voids

Non-wetting or non-contact


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Other Real-Time X-Ray Inspection Systems

from Glenbrook Technologies

JewelBox Series

80 or 90kV

5-7, or 10 micron FocalSpot size

7x-2000x magnification

5 Axis, 360oPositioner

RTX-113

35-52kV

20 line pairs/mmresolution (up to 100optional)

Variable Angle Viewingoption available

RTX-Mini

40kV

20 line pairs/mmresolution

Truly Portablecanbe hand carried orshipped!



11 Emery Ave

Randolph, NJ 07869

Tele: (973) 361-8866

Fax: (973) 361-9286

[email protected]

www.glenbrooktech.com

Manufacturers RepAaron Caplan

1310 E. Maple AveSterling, VA 20164

(703) [email protected]

www.gsaservice.com


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11 Emery Ave

Randolph, NJ 07869

Tele: (973) 361-8866

Fax: (973) 361-9286

[email protected]

www.glenbrooktech.com

Manufacturers RepAaron Caplan

1310 E. Maple AveSterling, VA 20164

(703) [email protected]

www.gsaservice.com

x-ray inspection bga glenbrook technologies

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