semi合集-English.pdf - 第6249页
SEMI G48-89 © SEMI 1989, 1996 6 5.21.2 Pin Marks (e.g. , Pin 1 i ndicator at end of pack age). 5.21.2.1 Equipment — Toolmaker’s Microscope . 5.21.2.2 Focus the micros cope on the surface of the package and measure the di…
SEMI G48-89 © SEMI 1989, 1996 5
5.17.2 The measurement is made from the intersection
of the straight part of the shoulder with the shoulder
bend radius of the lead on one side of the package to the
same point on the lead on the opposite side of the
package. Locate this point on the first lead by lining up
the vertical comparator cross hair with the straight of
the lead. Bring the center point of the cross hair to this
intersection. Zero the readout, move to the opposite
lead, and repeat the location of the intersection. Record
the measurement.
NOTE: Due to shadowing of leads, only the end leads on the
package can be measured. A visual check with a 10 to 20×
microscope should be made to check for gross difference of
other leads.
5.18 Surface Finish
5.18.1 Comparative Method — (EDM Finishes only)
5.18.1.1 Equipment — Charmille Standard Surface
Gauge Binocular Microscope and Light.
5.18.1.2 Insert gauge and molded package to be
checked into a holder so that both can be viewed at the
same time under the microscope.
5.18.1.3 Estimate the surface finish on the package.
5.18.2 Absolute Method
5.18.2.1 Equipment — Automatic Surface Analyzer
Surface Standards.
5.18.2.2 Calibrate the analyzer using the gauges.
5.18.2.3 Measure the surface finish on the package.
The analyzer gives the average roughness (R
a
) and the
actual surface roughness. Use average roughness for
acceptance.
5.18.3 Table of approximate equivalent finishes
Mirror
Satin
Extra
Fine
Fine
Medium
Course
Micro
Inches
4 30 ± 10 50 ± 10 75 ± 10 105 ± 10 145 ± 10
Charmilles N/A N/A 18–21 21–24 24–27 27–30
Microns N/A 1 1.5 2 2.5 3.5
5.19 Radii
5.19.1 Comparative Method
5.19.1.1 Equipment — Optical comparator at 20×.
5.19.1.2 Radii are measured by comparison to known
radius overlays marked at the same magnification as the
comparator.
5.19.2 Absolute Method
5.19.2.1 Equipment — Toolmaker’s Microscope.
5.19.2.2 Radii are measured using the reticle lines and
the X and Y axes to obtain the radius.
5.19.2.3 Care must be taken to assure that each radius
is measured separately.
5.20 Lead Position
NOTE: Lead position is a combination of pitch variations due
to lead movement after forming and lead width. If the lead is
to fit a solder pad or hole, the combination must be
considered. In some cases, the lead width can be a major
contributor to poor lead position, eg. SO packages with gull-
wing leads, PCC with J bend.
5.20.1 Comparative Method
NOTE: This method will only determine if the part is usable,
not the breakdown of width and pitch variations.
5.20.1.1 Equipment — Optical Comparator at 20×.
5.20.1.2 Align the package to an overlay displaying
limit lines for lead pitch/width.
5.20.2 Absolute Method
5.20.2.1 Equipment — Toolmaker’s Microscope.
5.20.2.2 Move to the edge of the lead number and zero
the readout.
NOTE: Where there is a definitive end to the lead as in the
case of SO, SIP and DP, the end of the lead at the intersection
of the lead in feature, will be the measurement point. Quad
PCC packages will be measured at the top of the “J” bend
when in the “Dead Bug” position.
5.20.2.3 Move to the opposite edge of that lead and
record width.
5.20.2.4 Move to the first edge of the next lead. Record
the measurement. Repeat the width measurements.
5.20.2.5 Repeat for all leads to be measured.
5.20.2.6 Pitch can be calculated from the
measurements.
5.21 Draft Angles
5.21.1 Package Sides
5.21.1.1 Equipment — Optical comparator at 10x.
5.21.1.2 Lay the top or bottom surface of the package
squarely onto the comparator to insure that no
protrusions on the surface cause the package to be
tilted. Align the horizontal cross-hair to the leadframe.
Using the vertical cross hair, compare the draft angles
to an overlay.
NOTE: This measurement should be taken before the leads
are formed.
5.21.1.3 Repeat the procedure for all sides of the
package.
SEMI G48-89 © SEMI 1989, 1996 6
5.21.2 Pin Marks (e.g., Pin 1 indicator at end of
package).
5.21.2.1 Equipment — Toolmaker’s Microscope.
5.21.2.2 Focus the microscope on the surface of the
package and measure the diameter of the pin hole. (D1)
5.21.2.3 Focus on the bottom surface of the pin hole
and measure the diameter. (D2)
5.21.2.4 Tangent of Draft angle = (D1 – D2)/2H where
H is pin depth from Section 5.12 or cavity thickness.
5.21.2.5 In some cases ejector pin holes may require
measurement if a deep hole is specified.
5.22 Lead Spread — (Figures 1, 7, and 7a)
5.22.1 MDIP, SO — (Figure 7, 7a)
5.22.1.1 Equipment — Optical Comparator at 10×
Magnification.
5.22.1.2 Place the package squarely on the comparator
with the leads “UP” and find the mid-point of the
bottom cavity width.
5.22.1.3 Measure the distance to the outer edge of each
row of leads at the widest point of spread.
5.22.2 PCC (J bend lead dimension) (Foot Print)
Measure from perpendicular to the greatest extension of
the “J” radius of the leads on one side of the package to
the perpendicular tangent to the greatest extension of
the “J” radius of the leads on the opposite package side.
(See Figure 1.)
5.23 Foot Angle — (Figure 7)
NOTE: Applies to gull-wing leads.
5.23.1 Equipment — Optical Comparator at 20×
Magnification. Device Holding Fixture (see Section
5.16).
5.23.2 Place the device in the fixture, so that the flat
section of the leadframe at the junction with the plastic
body rests on the fixture’s flats. Leads to be facing
“UP”.
NOTE: Do not rest the radiused sections of the leads on the
flats. Be sure that all mold flash is removed from the area of
the frame that rests on the flats.
5.23.3 Measure the angle of the foot with respect to the
horizontal.
5.24 Foot Length — (Figure 7)
NOTE: Applies to gull-wing leads.
5.24.1 Equipment — Optical Comparator at 20×
Magnification. Device Holding Fixture (see Section
5.23).
5.24.2 While the foot angle is being measured, place a
circle template that contains the same radius as the
formed part onto the comparator. Align this template to
the radius of the outside bend. Where the radius of the
template meets the radius of the outside bend, this is the
tangent point to measure foot length.
5.25 Stand-Off
5.25.1 Measure the plastic stand-off, when applicable,
using the procedures of Section 5.12.
5.26 Lead Sweep
5.26.1 Equipment — Toolmaker’s Microscope or
Optical Comparator.
5.26.2 Method
5.26.2.1 Determine centerline of lead at egress of lead
from molded body (CL1) (see Figure 4).
5.26.2.2 Determine centerline at the end of the lead
(CL2). The difference between the two centerlines
CL2 – CL1, shall be the lead sweep.
NOTE: On “J” lead devices, the end of the lead is defined as
the bottom of the “J” lead radius.
5.26.3 Cautionary Notes
5.26.3.1 Verify centerlines on leadframe before
measuring to ensure lead-frame is correct.
5.26.3.2 Verify lead position in relation to the top
cavity centerline.
SEMI G48-89 © SEMI 1989, 1996 7
Figure 1
Figure 2