2 d, 2.5d, and 3d x ray inspection – what’s a “d”?

www.creativeelectron.com

2D, 2.5D, and 3D X-Ray Inspection – What’s a “D”?

Dr. Bill Cardoso


Introduction to Creative Electron

• USA designer and manufacturer of x-ray machines– 2D, 2.5D, and 3D CT Machines– Parts Counter

• Acquired FocalSpot in 2016– Only authorized support for all FocalSpot and Nicolet

x-ray machines

• IPC trainer center – certification for 600, 610, …

D = Dimension


What are dimensions?

x

y

x

z y

x

1D 2D 3D


How does it apply to x-rays?


Today we’ll discuss 3 different x-ray imaging modalities:

• 2D x-ray imaging• 2.5D– Tilted view

• 3D– Type 1: Planar tomography (limited angle 3D),

laminography and tomosynthesis– Type 2: Real 3D, Computed tomography


2D x-ray imaging

Slide7

Imaging Analysis

1. X-ray TubeProduces high resolution x-ray beam cone

2. Flat Panel

3. ComputerAnalyzes Image

PCB


Penetration Density and Thickness

Slide8

PCB’s & Solder Joint materials block x-rays based on:◆ Material Density (Lead, Copper, Plastics, Heat Sinks, etc.)

◆ Material Thickness

t

Lightest- Darkest


Computer prefer a gray scale (0-255)

X-rayImage

200

128

60

250


Field of View (FOV)

FOVInfluences:

• TestThroughput

• Resolution/Detection

• Clearance

.25in

6.4mm

1.0in

25.4mm

.5in

12.7mm

LowResolution

HigherResolution

LargerFOV

SmallerFOV


Resolution

• Resolution is measured as Line Pairs – X-ray Tube spot size

– Detector resolution– Field of View

• Resolution Influences– Clarity of image

– Measurement repeatability – Detection capabilities– False calls

Slide11

.5in(12.5mm)FOV 1in(25mm)FOV


How to find defects with 2D X-Ray imaging?


BGA voiding, shape, size inspection


Example Defect Detection


Are these images 2D or 3D?

2.5D X-Ray


BGA Head In Pillow Visual Inspection

So what’s 3D X-Ray?


There are 2 types of 3D x-ray inspection:

Type 1: limited angle computed tomography or planar tomography:

Tomosynthesis or laminography

Type 2: full computed tomographyCT


Type 1: Tomosynthesis vs LaminographyAlso called “Planar CT”

Laminography• MechanicalImageIntegration

GenerateOff-axisX-rays

RotatingDetector

Tomosynthesis• DigitalImageSynthesis

StationaryDetector

GenerateOff-axisX-rays


Principle of Laminography

* Z-Axis Mappingrequired


Principle of Laminography

• Steer-able x-ray source and rotating detector

• “Smear/Average” out objects above/below focal plane

• Mechanical integration generates one slice per rotation (or acquisition)

• Image acquisition and synthesis occur concurrently

Slide41

Off-axisimages


Principle of Planar CT

Large AreaDetector

Steer-ableX-Ray Source

Inspection Plane

MultipleTransmission Images



Planar CT is a Computational Technique

• Objects at different elevations move bydifferent horizontal distances

Z= X / tan Z

X



PlanarCTisa

ComputationalTechnique

• Objects at different elevations move bydifferent horizontal distances

Z= X / tan Z

X



Use multiple off-axis x-ray images to separate top/bottom overlapping or obscured solder connections

QFP

ResistorPCB

Top Side

Bottom Side

Cross Section x-ray provides the capability to generate un-obscured views of top and bottom side components


Imaging Performance

Planar CT 2D

Betterimagequalityandlowernoisereducefalsefailsandincreasesfaultdetection.


So what’s Computed Tomography?


Type 2: Full CT

• A 3D Non Destructive Testing control

• Tomography consists first in the acquisition of several radiographic projections of a given object

• As a second step, from the acquired projections, tomography consists in processing a 3D homothetic clone of the object by the mean of a 3D reconstruction software


RADIOGRAPHY TOMOGRAPHY

Radiography

Tomography slice2D

Tomographyreconstruction3D

Basic principles of computed tomography

Object

Flatfiled detector

Rotating table

RXGenerator

Object

Acquire radiographyimages

Pre-processingfiltering Reconstruction InterpretationPost-processing

segmentation, features extraction


CT technology advantages

• Positionning defects in3axis(X,Y,Z)

• Slicevisualisation:withoutinformationsuperposition

• Postprocessing :ü Surfaceextractionü Segmentationü Measurementsü ReverseEngineering


CT Example: Apple AirPod


Apple AirPod


Windshield Wiper Handle


Pacemaker Battery


Reverse Engineering


Tire Pressure Sensor


Technology summary

2D

2.5D

3D


X-ray technology comparison

Feature 2D 2.5D 3D - Planar 3D - CTImaging principle Transmission thru

materialTransmission thru material at angle

Layers reconstructed

from few transmission

images at different angles

Slices reconstructed

from many transmission

images at different angles

Field of view Large Medium Small LargeImage quality Great Great Ok GreatResolution High High Low HighInspection speed Fast Fast Slower SlowerApplications Everything PCB PCB Everything +

small PCB


Thanks for your time!+1 866.953.8220

[email protected]
