Somacis Zigzag PCB #1 QA Report - PowerPoint Presentation

Slide1

Somacis Zigzag PCB #1 QA Report

B.Azmoun

, BNL

March 7, 2017Slide2

Inspecting Somcis PCB zigzag using microscope

SECTION 1

SECTION 2

SECTION 3

SECTION 4

SECTION 5

Inspected 5 different regions of PCB to gather statistics for the

fabricated ZZ

pattern

2Slide3

Method

Length calibration of microscope traced to certified standard

Measured pad pitch=2.001mm

Design=2.000mm

Measured zigzag period =586um

Design=587um

Since pad pitch and ZZ period are reproduced very accurately, these may be used as a reference for the measurement of

other, smaller scale features

PCB ZZ period used here as length reference scale for high precision length measurement at the 100 micron level

3

Trace width

Gap width

Gap width-prime

SCALE

MeasurementSlide4

Statistics

(um)

Trace width

Trace width

near Trough

Gap width

Gap width

near Tip

Gap width prime

tip to tip dist.

Section1

148

158.4

84.5

87.4

557.7

350.9

139.3

154.1

81.8

88.8

569.3

349.5

84.7

87.5

84.9

84.9

     84   1143.7156.384.087.2563.5350.2Section Avg.Section2141.8146.585.185.1567.9355.3 142.1154.482.285.1576.6362.6 140.7 86.189.4   141.8 83.6   2141.6150.584.386.5572.3359.0Section Avg.Section3142.2150.786.579.3549335.5 138.5153.880.783.8553.4331.1 141.8148.377.889.4     83.8   3140.8150.982.284.2551.2333.3Section Avg.Section4139.3160.680.584.8559.2344.2 141.3156.679.381.8557.8344.2 141.8 83.1    142.9 79.1      80.5   4141.3158.680.583.3558.5344.2Section Avg.Section5137.2149.283.889.8567.9364.6 136.915089.690.2570.8360.2 136.4 87.9    135.6 87.5      86.9   5136.5149.687.190.0569.4362.4Section Avg.Overall Avg.140.8153.283.686.2563.0349.8

4Slide5

Trends

There appear to be no position dependent trends for the measured attributes of the PCB (

ie

, curves are flat)5Slide6

Summary of Results

4 Defining Parameters of Zigzag pattern

DESIGN

PCB (Avg

.

of

Measurements)

Pad pitch (p)

2.000

2.001

mm

zigzag pitch (d)

0.587

0.586

mm

gap (g)

0.075

0.084

mm

trace width (s)

0.155

0.141

mm

Resultant

Zizag

characteristics

DESIGN

Calculated attributes based

upon measurement of 4

param

.

Directly measured attributes

zigzag characterisitic angle

6.604

6.442

?

deg.g'0.6520.7450.563mms'1.3481.2551.437mmStrip Overlap1.8821.8531.650mmStrip Offset-0.534-0.598-0.213mmTip-to-Tip Dist.0.1180.1470.350mmStrip Overlap / Pitch94.192.782.5%Gap / Pitch3.84.24.2%Electrode Area / Tot. PCB Active Area67.462.7?%The reason that the values in the 2nd column differ from the corresponding quantities in the 3rd column is due to deviations of the PCB pattern from a true zigzag geometry(See next slide)6Slide7

Distortions in PCB pattern

7

We’ve identified several distortions in the

features of the PCB electrodes which result in a pattern that deviates from a strict zigzag geometryOver-etched tipsOver-etched trace width (& Trace width waist)

Under-etched troughs

Critical items:The over-etched tips may substantially diminish the performance of the PCB (vis-a-vis reduced charge sharing)

Gaps larger than the design spec. and trace widths narrower than the design spec. will also impact the performance by reducing the amount of copper conductor covering the active area (vis-a-vis larger field distortions near pads)

Minor items:

The trace waist is a small artifact that likely has little impact on the overall design, therefore a waist at the level shown here is tolerable.

The under-etched troughs, though significant in scale, likely have a small impact on the performance and therefore this distortion is tolerable at the levels shown here.

Eroded

Tips

Rounded

Troughs

Slight

Waist

140.8um

153.2um

118um (94% overlap)

350um (83% overlap)

563um

745um

Tip-to Tip dist.