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Chapter 5 Libraries 5-79  Fiducial Surface Material and Illum inator Settings The ideal fiducial surface is of bare copper or of gold/nickel plating. Fiducial surface for epoxy fiberglass board may be of leveled solder,…

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5-1-5-13 Fiducial Marks

production lot. This model will be the reference to be compared with the actual fiducial on each

board. The fiducial process allows the system to measure and compensate X/Y/T offsets and

stretch/shrink of the board pattern to achieve precise placement for the overall program.

 Fiducial Process

There are two ways to perform the fiducial process:

1. Pattern matching

This process allows for comparison between the registered fiducial model and an actual

fiducial on a board to see the offset between them. Its capability is hardly susceptible to the

inconsistent lightness of the overall or part of the fiducial image, or to the unclear fiducial

image due to its unsmooth surface. It is recommended that this process should be selected.

2. Center search based on fiducial shape

This process does not require time-consuming model registration unlike the pattern matching.

It merely requires you to select a fiducial shape to perform fiducial center search.

z Fiducial Mark Centering

The coordinates of the center of the fiducial model must correspond to the programmed

fiducial coordinates. If the fiducial model is registered off-centered, the offset value is added to

the compensation value to result in mis-compensation for all the production lot. To prevent this,

in teaching the fiducial model, the Model centering allows a fiducial to be centered

automatically by the vision process system, not manually, for proper registration. Before this

feature can be used, the fiducial shape and size must be specified.

Summary of processing

Center search by

specifying shape

Pattern matching

(Actual model)

Model centering

Acquire model

Pattern matching

(Template model)

dimensions.

Acquire model

The “Actual model” for fiducial ‘Pattern matching process’ is registered actually

captured by the teach camera.

On the contrary, “Template model” for fiducial ‘Pattern matching process’ is

created from the specified mark shape and input sizes. “Template model” is

recommended to use for the fiducial pattern matching process because;

① The “Template model” does not require model centering and an accurate

mark model can be created.

② Besides, illumination setting of “Template model” can be adjusted by Image

Test even after model registration to get a better result of “Actual score”.

③ Only common mark shapes; circle, square, diamond, and triangle, are

available for “Template model”.

④ Use “Actual model” for the rest of mark shapes.

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 Fiducial Surface Material and Illuminator Settings

The ideal fiducial surface is of bare copper or of gold/nickel plating.

Fiducial surface for epoxy fiberglass board may be of leveled solder, copper, and gold plating.

For ceramic board may be of silver/palladium. These materials, especially leveled solder, may

have irregular reflectance because of their unsmooth surface. Accordingly, the captured

fiducial image may not be just like the real target. To improve this, prior to registering the

fiducial model, adjust the Inside/Outside Light settings of the main teach camera.

Note: When it is impossible to obtain a satisfactory model image even after adjusting illuminator

settings, see the Distance X/Y setting in the following section.

 Creating Fiducial Data

Note: Mark image data cannot be opened/edited in Image Library, but in Program editor. Mark

image editor window above should be opened from:

Program>Tool>Fiducial/Badmark or button on the Program Edit screen.

Window:

File>Open: Opens the list of existing fiducial data. Select data and click <Open>

button. To delete data, select data and click <Delete> button.

File>Save As…: Saves the current file with a name and comment. Comment is not

necessarily required.

File>Save: Overwrites the current file.

File>Exit: Closes the Fiducial Data dialog box.

Algorithm: Click the mode select combo box to select “Pattern Matching” or

“Center Search”. If “Pattern Matching” is selected, comparison will

Mode selecting combo box

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be made between the mark data registered to the image library and

the mark captured by the camera.

If “Center Search” is selected, fiducial marks can be processed by

specifying the model shape, even if the model is not acquired. For

this, the mark center is searched using the mark shape. This

algorithm simplifies operation since no model is registered.

Mark Code: To create new fiducial data, enter a desired code. To edit existing

data, click File>Open to select data. This code serves to link the

fiducial data and the placement & mark data.

* Up to 38 characters can be entered.

Comment: Any appropriate comment.

* Up to 40 characters can be entered.

Model Select “Actual Model” or “Template Model”.

The “Actual model” is registered actually captured by the teach

camera. On the contrary, “Template model” is created from the

selected mark shape and input sizes. “Template model” is

recommended to use for the fiducial pattern matching process

because;

① The “Template model” does not require model centering. An

accurate mark model can be created.

② Besides, illumination setting of ‘Template model” can be

adjusted by Image Test even after model registration to get a better

result of “Actual score”.

③ Only common mark shapes; circle, square, diamond, and triangle,

are available for ‘template model’.

④ Use “Actual model” for the rest of mark shapes.

Fiducial Shape: Used for the model centering function for model registration, or for

the center search process not using the model. Select the number of

the fiducial shape (not an alphabet) referring to the list box below

the image box and enter the number to the setting field.

(Double-click an item in the list box is also available to set the

number.)

Available shapes are as follows:

Circle: 

Square: ■

Diamond:



Triangle: S

Cross:



Check:

Corner Square:

Mark X: Enter the actual length of the mark in horizontal direction.

* Increment : 0.01mm

Mark Y: Enter the actual length of the mark in vertical direction.

* Increment : 0.01mm

Mark X

Mark Y

Fiducial mark

Fiducial Model

Distance X/Y: Usually fiducial process is performed at the programmed fiducial

coordinates (to which camera center is aligned).