Journal of the HKPCA / Issue No. 50 / 2013/ Q412

Technical Paper

PCB

(Stripline)

(Df) (Rz)

(Test

Coupon or Vehicle)

(Df)

(Rz)

PCBPCB

The main factors of PCB AttenuationThe main factors of PCB Attenuation

Vic WONG / TTM Technologies - Dongguan Meadville Circuits Limited/ -

PCB

The main factors of PCB Attenuation

Abstract:

Key words:

PCB's attenuation sometimes was called

transmission loss or insertion loss (S21) as well.

This article has summarized the main factors of

attenuation of PCB's stripline structure based on

the exper iments: t ransmiss ion l ine length ,

laminate's loss tangent (Df), copper foil's surface

roughness (Rz), line width, backdrill and via stub.

According to customer's stackup, a test coupon or

vehicle with different parameters' combination can

be adjusted and tried, and then a good attenuation

product can be achieved.

Attenuation, Transmission Loss, Loss

Tangent (Df), Surface Roughness (Rz), Resin

Content, Skin Effect, Skin Depth, Line width,

Backdrill and via stub

( 1)

( )

1 Intel

PCB

2.1

Attenuation or Transmission Loss

(dB)

dB/m

(VNA: Vector Networks Analyzer 2) 3

PCB H OZ 155mm 90 m

(

GHz 0.4Ghz) (dB

) 3

PCB

( 4)

PCB

dB/m

µ

2.2

13www.hkpca.org

Technical Paper

2.3 (Df)

3 5 (Stripline

)

( Panasonic R-1755V R-5725)

VNA 6

2 Agilent N5247A

3 PCB HOZ 155mm 90um

4

R-1755V

R-5725

Df SPP (Short Pulse

Propagation technique)

1GHz (Df) 0.023 0.008

(Skin

Effect) ( 7)

(Skin

Depth) 7

(Df)

2.4 (Rz)

5 Stripline

6 Panasonic R-1755V R-5725

Journal of the HKPCA / Issue No. 50 / 2013/ Q414

Technical Paper

7 (ac) (

)

100MHz

7 m 10,000MHz (10GHz)

1 m

(Rz)

(Standard Foil) 7~8 m VLP (very Low

Prof ile) 3~5 m

100MHz

9 1 OZ 6mil

(Ra Rz

Ra Rz )

µ

µ

µ

µ

2.5 (Line width)

Stripline ( 10) 1 OZ

4.3+/-1 mil

4.3mil

0.4mil 4.7mil

1

35 0.4mil

3.5% ( 11)

8

9

10 Stripline

11

2.6 (Backdrill)

(via stub)

Broadside-Coupled Stripline

( 12 Broadside)

7 L5_L6 L8_L9

L 1 1 _ L 1 2 L 1 5 _ L 1 6 L 1 8 _ L 1 9 L 2 1 _ L 2 2

L24_L25 via

stub 7

(SDD21) 13 26

5.7mm Test pads L1

stub stub

stub

via stub

(Resonance) stub

7 (L26)

( 15) 14

via stub

12 Broadside-Coupled Stripline

13 7 Broadside stub

14 (

L25 ( ) L22 L19 L16 L12 L9 L6)

15 7 Broadside

3.1

PCB

(Stripline)

dB/m dB/in

dB

15www.hkpca.org

Technical Paper

Journal of the HKPCA / Issue No. 50 / 2013/ Q416

Technical Paper

3.2 (Df)

3.3 (Rz Ra)

3.4 (Line width)

3.5 (Backdrill) (via stub)

(Df)

(Resin Content)

Df

PCB

PCB

PCB

stub

(backplanes)

1.

PCB

PCB (Optical

PCB) PCB

Ra Rz

1. Ra: (arithmetical mean

deviation of the assessed prof ile)

Ra

Z Ra Ra

Ra

Ra

Ra 0.025~6.3 mµ

2. Rz (maximum height of prof ile)

Rz 5

5

[1] D r. E r i c B o g a t i n < S i g n a l I n t e g r i t y > ,

http://www.bethesignal.net/bogatin/

[2] IPC-TM-650 2.2.17A, Surface Roughness and

Prof ile of Metallic Foils (Contacting Stylus

Technique)

[3] P o l a r C I T S 8 0 0 s U s u a l M a n u a l ,

http://www.polarinstruments.com

[4] Intel SET2DIL: Method to Derive Differential

Insertion Loss from Single-Ended TDR/TDT

Measurements, Jeff Loyer, Intel Corp.

[5] Agilent Network Analyzer Basics

[6] IPC-TM-650 2.5.5 .12, Test methods to

Determine the Amount of Signal Loss on

Printed Boards (PBs)