IPC-4556 印制板化学镍钯浸金（ENEPIG）规范ENG - 第38页

Supporting Section Above Figure A4-SS-1 displays overlay of one spectrum collected on half ounce Cu/epoxy and spectrum of one ounce Cu/epoxy . Blue trace is from half ounce Cu/epoxy , red trace is from one ounce Cu/epoxy…

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Table A4-1 Summary of XRF Configuration Solutions Offered for Measurement
of ENEPIG Plating on PCB’s with Advantages and Disadvantages
ENEPIG
Layer Proportional Counter XRF Solid State Detector XRF Vacuum & Solid State Detector XRF
Au 1. Use peak deconvolution to correct
for Br interference
2. Check calibration at least twice a
day - drift correct or recalibrate as
needed
3. Difficult to measure <51 µm
4. Measure time 60 - 90 sec
depending on collimator size
5. Can measure areas as narrow as
76 µm wide or 102 µm diameters
with longer measurement times
(120 sec)
1. No deconvolution needed - can
measure <25 µm - better overall
accuracy
2. Good long term stability
3. Measure areas <305 µm wide -
impractical unless instrument
configured with x-ray optic
4. Measure time 60 - 90 sec; longer
for layers <25 µm. Less time if
collimator is 508 µm or larger
or if x-ray optic used.
1. No deconvolution needed - can
measure <25 µm - better overall
accuracy
2. Good long term stability
3. Measure areas <305 µm wide -
impractical unless instrument
configured with x-ray optic
4. Measure time 60 - 90 sec; longer
for layers <25 µm. Less time if
collimator is 508 µm or larger
or if x-ray optic used
Pd 1. Must use background correction
methods unless Cr target source
used
2. Measurement of Pd <51 µm is
problematic unless Cr target
source used
1. Must use background correction
methods unless Cr source or x-ray
optics used
2. Measurement of Pd <51 µm is
possible with longer measurement
times
3. Measure areas <305 µm wide
impractical unless instrument
configured with x-ray optic
4. Use of Cr target source or x-ray
optics improves precision, reduces
time
1. Must use background correction
methods unless Cr source or
x-ray optics used
2. Measurement of Pd <51 µm is
possible with longer measurement
times
3. Measure areas <305 µm wide
impractical unless instrument
configured with x-ray optic
4. Use of Cr target source or x-ray
optics improves precision, reduces
time and allows for measurement
of minimum of 7.6 µm
Ni-P Correct thickness measurement for
difference in % P between calibration
Most accurate - measures % P
and corrects thickness of Ni layer
Correct thickness measurement for
difference in % P between calibration
standard and sample
standard and sample
automatically
January 2013 IPC-4556
27
Supporting Section
Above Figure A4-SS-1 displays overlay of one spectrum collected on half ounce Cu/epoxy and spectrum of one ounce
Cu/epoxy. Blue trace is from half ounce Cu/epoxy, red trace is from one ounce Cu/epoxy. Note the significant reduction in
Br peak when Cu thickness increases from half ounce to one ounce. Also note the difference in background levels in the
indicated region of the spectrum where Pd intensity will be counted. Again, background ‘‘noise’’ decreases as Cu thickness
increases.
Figure A4-SS1 XRF Spectra of 1/2 oz Cu/Epoxy vs. 1 oz Cu/Epoxy
Smoothed, Comparison of Cu epoxy half ounce.cts(blue) vs. Cu epoxy one ounce.cts(red)
0.9
795
Br Pd
636
477
Br from epoxy
Background noise
in Pd region
318
159
0
8.4 15.8
KeV
Counts
23.3 30.7 38.2
IPC-4556 January 2013
Spectral Analysis Mode- WPHA
28
Fle Edt Yew Display Ogerations ROI Help
BLUE
Dx 2109.2
Peak(Ch.,KeV,Cts)
１９１，８．０，１２５４８．６
Ready
讼
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NM[
Above Figure A4-SS-2 displays spectrum from typical ENEPIG plated Cu sample (no epoxy) and spectrum from one ounce
Cu/epoxy (blue trace). Note the Red peak near Br is the Au L-β peak without any Br interference since the substrate for this
sample had no epoxy. The figure illustrates how close the energies are between the Au L-β peak and the Br K-α (blue trace,
marked as Br). Without peak deconvolution these peaks would be summed as one peak and erroneously interpreted as
immersion Au thickness.
Figure A4-SS2 XRF Spectra of ENEPIG Plated on Cu (No Epoxy) vs. 1/2 oz Cu/Epoxy
Smoothed, Comparison of Cu epoxy half ounce.cts(blue) vs. ENEPIG Cu.cts(red)
78
0.9
0
Br
Pd
624
468
Combined Au + Br
Pd peak “sits” on top of
background. It’s height
depends on Pd thickness
AND background level
unless background
subtraction is us
(from epoxy)
ed
312
156
0
8.4 15.8
Count
KeV
s
23.330.7 38.2
January 2013 IPC-4556
Spectral Analysis Mode-WPHA
29
Ele Edk Yew Display Operations BOI Help
BLUE
Dts: 00
Peak(Ch.,KeV,Cts)
１９３，８．１，１４８９３．２
Ready
△
lo bs
简首首当指
INUM