Specification_SIPLACE_S23HM_eng - 第19页

18 Description Different reference mark shapes prove to be optimal depending on the condition of the surface. Particul arly advi sable for bare co p- per su rfaces with little oxida tion is the single cross. Maximum reco…

Target Low

Structure Correlation

Description

With the SIPLACE S-23 HM, sev-

eral vision modules with a central

vision system to analyze recorded

image data ensure high placement

precision.

At one of the machine’s two X-

gantries the PCB vision module

recognizes offsets in the position

of the PCB in the conveyor sys-

tem. The modules are also re-

quired to scan the machine or the

feeders on one side of the table.

Each vision module consists of a

CCD camera with integrated light-

ing and optics.

The offsets in PCB position are de-

termined with the help of at least

two - but generally three - refer-

ence marks on the PCB. When the

PCB arrives, the gantry with its

PCB vision module moves to the

programmed mark position. The

vision system compares the re-

corded video image with the sam-

ple stored in the PCB description.

By applying the correlation princi-

ple the vision system can deter-

mine the correct position through

comparisons with programmed

target structures even when refer-

ence marks are incomplete or

damaged (actual structures).

The shapes are not inviolably

specified; they can be taught with-

out restrictions.

Additional functions of the PCB vi-

sion module are the position rec-

ognition of the feeders and ce-

ramic substrates (optional) and the

calculation of processing data in-

cluding mapping.

In addition, recognition of faulty

PCBs is conducted via ”ink spots”

with the aid of the PCB vision

module.

Vision Sensor Technology:

PCB Vision Module

Technical Data

Reference marks

Local marks

Library memory

Recognition of poor panels

up to 3 (subpanels and multiple panels)

up to 2 per component

(may be of different type)

up to 255 types of reference marks

per subpanel

Image analysis Correlation principle

based on gray-scale values

Lighting method Front lighting

Recognition time

mark/ink spot

0.8 s

Camera’s field of view 5.7 x 5.7 mm

Correlation Principle

Actual High

Structure Correlation

Description

Different reference mark shapes

prove to be optimal depending on

the condition of the surface.

Particularly advisable for bare cop-

per surfaces with little oxidation is

the single cross. Maximum recog-

nition reliability is achieved due to

the high information content. Rec-

tangle, square and circle are less

”informative” but save space, are

rugged, and can even be used

when oxidation is at an advanced

stage.

Advisable for tinned structures are

circle or square because in this

case the ratio of the mark dimen-

sions to the presolder thickness is

particularly favorable.

Vision Sensor Technology:

PCB Position Recognition

Template

Window

PCB Camera

Field of View

Area

Fiducial to

Be Located

Reference

Fiducal

Reference Mark Criteria

Locate 2 marks

Locate 3 marks in addition

X-/Y-position, rotation angle, mean dis-

tortion

Shear, distortion in X- and Y-direction

Mark shapes Freely definable via teaching, e.g.,

single cross, rectangle, square, circle

Mark surface

Copper

Tin

Without oxidation and solder resist

Warp ≤ 1/10 of structure width,

good contrast to environment

Mark dimensions

single cross

rectangle/square

circle

Length and width: 0.9 - 2 mm

Line thickness: 0.3 - 1.0 mm

Edge length: 0.5 - 2 mm

Diameter: 0.5 - 2 mm

Mark environment Clearance around reference mark not

necessary if there is no similar mark

structure in the search area

(5.7 x 5.7 mm)

Description

In cluster technology, each sub-

panel is assigned an ink spot. If

this is present when the PCB vi-

sion module conducts the meas-

urement, the pertinent subpanel is

not populated.

Naturally, it is also possible to pre-

vent the population of the sub-

panel when the ink spot is miss-

ing.

This function can be used to pre-

vent costs incurred by unneces-

sarily populating faulty subpanels.

n n

n R

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f f

f F

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eed

The pick-up position of the com-

ponents can be determined pre-

cisely with the aid of the position

recognition of the feeder. It is acti-

vated each time after a change of

feeder or component table. The

offset in position relative to the

stored ideal position is determined

on the basis of fiducials on the

feeder modules using the PCB vi-

sion module. This provides a very

high pick-up reliability even for the

very first component. This is par-

ticularly important with small com-

ponents.

Vision Sensor Technology:

Recognition of Faulty PCBs via Ink Spots

Position Recognition of Feeder

Ink Spot Criteria

Mark shapes Single cross (recommended because

of lowest susceptibility to problems),

rectangle, square, circle, etc.

Masking material Mat dark (light-absorbent)

Not advisable: white or glossy

Size of mark masking

Circular: Diameter ≥ 8.1 mm

Square: Edge length ≥ 5.7 mm

Mark recognition time

(Travel > 100 mm)

Mark masked: 1.2 s

Mark not masked: 0.4 s