YesAX V3.1.2 - Software User Manual.pdf - 第70页
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Recipe Creation Step by Step for 2D Recipes 6-11
You can create a perfectly functional AXI recipe using SmartCAD, even when the PCB is placed
90 or 180 degrees from the intended orientation.
Although SmartCAD is very efficient in determining needed information from “mystery” CAD
data, it should be used with caution. CAD data is the basis of the PCB assembly process but
SmartCAD creates usable AXI recipes without knowing much about the CAD data. This can
lead to bad consequences in the future when more advanced features are used, such as the central
library and standard package library.
Sharing part information across inspection recipes requires a consistent application of part
rotation information.
3D Recipe Creation 7-1
7 - 3D Recipe Creation
7.1 Basic Concepts and Terminology
3D inspection introduces several new concepts and terminology. It is important to have some
basic understanding of them before trying to create 3D inspection recipes.
1. Tomosynthesis
Tomosynthesis is a technique that digitally combines oblique angle images to compose cross
section slices of the object being imaged. In the X3 system, tomosysnthesis is used to
combine 4 to 72 oblique angle images to compose the cross section slice of the circuit board
being inspected.
2. Site and Future Site
A site is an XY location on the board where 3D inspection takes place. A normal site is
indicated as a white circle in the map view. A normal site contains the angle images taken at
the site. These angle images can be combined to form horizontal X-ray “slices” of the area. A
future site is a site without the angle images. It is indicated in the map view as a magenta
cross. Future sites can be converted into normal sites by selecting Re-Capture all Sites in
the 3D Control pop-up menu, or the Capture Image Set button in the 3D Future Site dialog.
3. Slice and Slice Number
A slice is a composed image that represents a cross section of the site area in horizontal
orientation. There are two fields of view on the X3 that produce slices of two thicknesses,
25.8 um and 12.9 um. In YesAx slices are given numbers to represent their relative height
position. The top surface of the board has slice number 0, the number increases with height.
Slices for the bottom side parts have negative numbers.
4. Pitch and Roll
By default, the 3D slice obtained from tomosynthesis is exactly horizontal and parallel to the
conveyor rail. In an ideal case that is parallel to the board surface. However, in a real
production environment, the board surface is not always flat. To achieve a precise inspection,
the X3 system does additional computations to produce a slice that is parallel to the board
surface even when the board surface is not flat. The software utilizes the height data obtained
from the laser height measurement and applies a “pitch” and a “roll” factor in the
computation of the slice.
5. Surface Height Referencing
For precise 3D inspections, height referencing is extremely important. The X3 machine uses
2 very different techniques to precisely locate both the top and the bottom board surfaces.
The laser height gauge profiles the top board surface. Although the laser gauge has a short
term repeatability of a few microns, in a production environment with temperate variation
throughout the day, the practical accuracy for the laser gauge is around 30 microns, which is
not good enough for some of the more critical inspection requirements. Moreover, laser
gauges cannot be used to profile the bottom surface. Board thickness variation is quite
common for post reflow boards. In the X3, lasers are used to profile the top surface height
and to provide data for the pitch and roll calculation. Then a software technique called “Auto
Calculate” is used to precisely locate both the top and the bottom board surfaces.