SSPA “Scientific and Practical Materials Research Centre of NAS of Belarus”Minsk

«Application of multilayer films screens for electromagnetic protection of electronic and scientific

equipment, providing of electromagnetic compatibility»

Grabchikov S.S, Trukhanov A.V.

2015

Objective and Assignment of multilayer films screens

Protection of electronic and scientific equipment from influence:

- External magnetostatic fields (MSF);

- Low frequency (LF) electromagnetic fields (EMF) in the range 50-10 000 Hz;

- Electromagnetic pulses;

- Electromagnetic compatibility of radio-electronic components and blocks equipment.

Main directions of shielding:

- Electrostatic fields;

- Magnetostatic fields;

- Low frequency (LF) electromagnetic fields (EMF);

- Electromagnetic radiation (plane wave)

Magnetostatic shielding

(1)

(2),S

lRm

Principle of magnetic field shunting by ferromagnetic materials

Shielding effectiveness (Э) is determined by the formula:

,D

d1Э

µ – magnetic permeability;d – thickness of shield;D – diameter of the equivalent spherical shield.

[М.Л. Волин Паразитные процессы в радиоэлектронной аппаратуре. М., «Радио и связь», 1981. с.61]

Value of magnetic flux resistance Rm :

S - cross sectional areal – average length of the magnetic induction lines through the shield

Conclusion: Maximum protection is achieved by materials with maximum values of μ and S

Materials µmax ЭH=2А/m ЭH=9А/m

79 HM 105 ~380 ~400

71 КНСР(ТО)

0,8∙106 ~140 ~300

71 КНСР(исх.)

0,8∙106 35 ~90

АМАГ-172(ТО)

1,5∙106 210 250

АМАГ-172(исх.)

1,5∙106 60 95

Calculation results of shielding effectiveness for equivalent spherical steel screens (μ = 100) as a

function of D and d [eq. (1), slide 4]

When D=50мм; d=1мм; Э=2.

For «Armko» Fe (µ=3000) D=400мм; d=10мм; Э=37,5;

Experimental results of shielding effectiveness for commercial soft-magnetic materials – permalloy (79HM) and amorphous alloys (71КНСР and АМАГ-172)

[П.А. Кузнецов, Б.В. Фармаковский ЦНИИ КМ «Прометей», РФ]

[В.В. Винников Основы преобразования РЭС. Электромагнитная совместимость и конструирование экранов. С-Пб. Северо-зап. государственный заочный технический университет., 2006, 164 с.]

Magnetostatic shielding effectiveness

The processes taking place during the electromagnetic wave transmitting through metal screen

[Henry W. Ott. Noise Reduction Techniques in Electronic Systems. – N.Y. I. Wiley and Sons. 1988. – 429p.]

мотротрпоглдБобщ АААА

f

ddАпогл

1;68,8

268,8

25,94lg20

4lg20

2

1 воздухадляотр z

zА

If Апогл 10 dB 3,16, Амотр can be neglected [Кечиев Л.Н., Акбашев Б.Б. Степанов П.В. Экранирование технических средств и

экранирующие системы. М.: ООО «Группа ИДТ», 2010. – 470с.]

Frequency dependences of shielding effectiveness as a function of absorption (a) and reflection (б) for

different electromagnetic shield with thickness 0.05 mm in the range 10-2 до 103 МHz:

1– (Сu); 2– (Al); 3 - (steel); 4 – (permalloy)

А

Б

Shielding effectiveness of industrial metallic materials (calculated data)

d, mm Cu Al Steel = 100

0,1 15 9,0 -

1,0 160 87 940

2,0 730 290 5,1*105

4,0 1,5*104 3,2*103 1,5*1011

Thickness dependences of shielding effectiveness (Э) at 10 kHz[Shapiro D.N. Fundamentals of the theory electromagnetic shielding. L. Energy 1975]

Frequencies dependences of shielding effectiveness (Э) for different materials (in dB)[Lin’kov L.M. et. al. Methods and tools for electromagnetic shielding. M. BSUIR, 2000]

Type of shield Material of shieldFrequency, Hz

10 100 103 104 105

metal sheetsThickness 0,5 mm

Steel 64 87 120 120 120

Cu 67 70 88 120 120

Al 65 66 80 120 120

metal meshes

Cu 0,1 mmUnit 11 mm

65 55 50 42 32

steel 0,2 mmUnit 11 мм

48 47 42 36 29,5

Shielding effectiveness of industrial metallic materials in LF range

(Experimental data. Plane samples 330×330 mm Е = 10V/m. )

Frequency; / material

Al Cu Ni Steel 3408

Aaronia X-Dream

Thickness; mm

0,8 0,8 0,5 0,6 0,15

50 Hz 1,5 1,1 2,1 35 47

500 Hz 1,7 1,1 2,8 50 63

5000 Hz 3,3 3,3 3,0 83 66

Electromagnetic shielding effectiveness by multilayer structures

Shielding effectiveness (SE) of multilayer structures consisting of metals with different wave

resistance is higher than SE of single-layer shields with the same thickness.

The shielding effect is due to the processes of absorption and reflection of EMW at interfaces.

In multilayer structures the role of the reflection effect increases with the differences of the wave

resistance and number of layers increasing.

[Чернушенко А.М. Конструкции СВЧ устройств и экранов. М. Радио и связь, 1983.]

0Z

Shielding effectiveness of double layer screen (Э12):)1( 212112 ГГЭЭЭ

Э1; Э2 – shielding effectiveness of the first and second layers respectivelyГ1; Г2 – reflection coefficients of the first and second layers respectively

reflection coefficient: )/()( 01020201 ZZZZГ

Shielding effectiveness of tree layer screen(Э123):

22

313221321123 )1()1(

Э

ГГГГГГЭЭЭЭ

Method of multilayer shields formation1. Composite or Multiple screens[Гроднев И.И. Электромагнитное экранирование в широком диапазоне частот. М.:

«Связь» 1972, 112с. системы - медь/сталь/медь; алюминий/сталь/алюминий; свинец/сталь/свинец; медь/алюминий/медь; медь/свинец/медь].

2. Vacuum coating [Гапонов С.Н. Свидетельство на полезную модель. РФ №16976, 27.02.2001].

3. Sequential pressing of dispersed materials[Шторгин В.С., Швырев Ю.Н., Шатохин А.Н. Патент РФ №200210891, 27.02.2004].

4. Chemical precipitation[A Comparison of Conductive Coating for EMI Shielding Application/ E/ Bastenbeck, et al.

// ITEM. 1995. p.100-106, 278-287.]

5. Electrolytic deposition [Дмитренко В.В., Батищев А.Г., Грабчиков С.С. и др. Патент РФ №2474 890. 27.05.2011].

Technology of electromagnetic multilayer film shields formation allows :

- high manufacturability in the forming process on conductive substrates; - Rigid fixation of the shields on conductive substrates;

- obtained single-layer and multi-layer film shields (thickness from 1 to 500 microns); - varying by number and thickness of the partial layers in multilayer film shields in wide range of

values;

Samples of device housings with electromagnetic shields

Samples of modular housing spacecraft equipmentwith multilayer shields

(1 sample - 190×160×160mm; 2 sample - 190×160×60mm)Sample of linear step motor housing with multilayer

shields

(bottom diameter 40 mm, housing diameter 28 mm, height 35 mm), NiFe [8x50mкm] + Cu [7x5 mкm]

Optical images of polished sections of multilayer shields

Sample №1: NiFe 50 layers +Cu 50 layers

Sample №2: NiFe 8 layers +Cu 8 layers

Sample №3: NiFe 5 layers +Cu 5 layers

Magnetostatic shielding effectiveness of single-layer and multilayer screens

(experimental data) cylindrical aluminum substrates - diameter 60mm, height 100mm

Magnetostatic shielding effectiveness of (FeNi/Cu) multilayer screens with different number of

magnetic layers (2, 5, 10, 20 and 40) at the equal magnetic layer thickness (10 mm) and Cu layer

thickness (2 mm).

200 400 600 800 1000 1200 1400 1600 1800 2000 2200

0

4

8

12

16

20

24

28

32

alloy 29НК (3 mm) 5х10 m

10х10 m

20х10 m

40х10 m

steel СТ20(3 mm)

Н (А/m)

Э

Magnetostatic shielding effectiveness of (FeNi) single-layer and (FeNi/Cu) multilayer screens with different thickness of magnetic layer (from 5 to 400 mm) and number of magnetic layers (1, 5, 10, 40 and 80) at constant thickness of Cu layer

(2 mm) . All samples characterized by the same total thickness of magnetic layers (400 mm).

0 200 400 600 800 1000 1200 1400 1600 1800 2000

10

15

20

25

30

35

40

45

Э

Н (А/m)

40х10 m 1х400 m 5х80 m 10х40 m 80х5 m

Application of screens for protection the fiber optic equipment from the influence of magnetostatic fields

Cap and body of the fiber optic devices with screens made of modular technology from AMA and electrodeposition technology (diameter 120 mm, height 20mm)

0 50 100 500 1000 1500 2000 2500

0

10

20

30

40

50

60

70

80

90

100 Amorphous strip 84КХСР Electrolitic alloy Ni

20Fe

80

Н (А/m)

Shi

eldi

ng e

ffec

tiven

ess

Shielding effectiveness of screens based on Ni80Fe20 alloy (single-layer at thickness 400mm) (∆) and amorphous strip 84KHSR (10x30 mm) (●)

Magnetostatic shielding effectiveness as a function of Ni80Fe20 thickness

0 500 1000 1500 2000 2500 3000 3500 40000

20

40

60

80

100

120э э

50 мкм

180 мкм

Н (А/м)

400 мкм

0

4

8

12

16

20

Field dependences of magnetostatic shielding effectiveness of Ni80Fe20 films - 50 (▲); 180 (◊) и 400 (○)

mm, (diameter 20 mm, height 40 mm)

Field dependence of magnetic permeability of Ni80Fe20 film with thickness 200 mm

Вывод: position of the maxima on the curves Э=Э(Н)and μ = μ (H) do not coincide to each other

Non-linear behavior of the magnetic permeability in thickness of the screen

Boundary conditions of the normal component of magnetic induction (BA1, BA2) and the tangential component of the magnetic field strength (HA1, HA2) at the interface of two media at the point A:

ВА1 = ВА2 и НА1 = НА2

Since the magnetic permeability is given by:

μ= μ(Н) и μ=В/Н, So: μА

1 = μА2

и μВ1 = μВ

2; :

μА1 = μА

2= μ(Н); μВ1 = μВ

2= μ(Н1)

Conclusion:

- magnetic permeability of the screen decreases as the penetration into the screen;

- values μВ

1; μВ2 in Э times less than μА

1; μА2;

- for correct determination the value of shielding effectiveness we have to considered as the main

magnetic characteristics of materials and the value of the magnetic field strength corresponding to the maximum value of the magnetic permeability.

Shielding effectiveness of NiFe/Cu multilayer shields

Shielding effectiveness of NiFe/Cu multilayer samples as a function of total thickness and number of magnetic layers at 50Hz (a) and 5 kHz (b)

[thicknesses of partial magnetic layer are: 5 mm; 10 mm; 40 mm and 200 mm; thickness of partial Cu layer – 3 mm]

Е = 10 V/m.

0 50 100 150 200 250 300 350 400 450

0

20

40

60

80

100

120

140

5 m 10 m 40 m 200 m

d,m

SE

0 50 100 150 200 250 300 350 400 450-5000

0

5000

10000

15000

20000

25000

30000

35000

SE=7215

5 m 10 m 40 m 200 m

SE

d, m

SE=1600

а b

Application for the protection of photomultiplier tubes (PMTs) from influence of static magnetic fields

(in cooperation with «MEPhI»)

Samples of PMT-85 with multilayer screen (left) and

without screen (right) Field dependences of the gain of PMT-85 without

screen and with multilayer screen

Practical application of multilayer shields based on NiFe for protection of EMR

(Multilevel hull construction - MHC) (in cooperation with “Testpribor”, Moscow)

Protection of 1-st level MHC from external static magnetic fields

0 500 1000 1500 2000

6

8

10

12

14

16

18

without screen with screen

Н (А/m)

Shi

eldi

ng e

ffec

tiven

ess

(dB

)

0 200 400 600 800 1000 1200 1400 1600

13

14

15

16

17

18

19

20

21

22

23

Sh

ield

ing

eff

ecti

ven

ess

(dB

)Н (А/m)

without screen with screen

Field dependences of shielding effectiveness for 1-st level MHC (steel ~2 mm) without screen and with screen in

different orientation of external magnetic field

Shielding effectiveness of MHC in LF range

• Sample “ТАСФ 735312.002” (thickness ~1mm); “ТАСФ 745535.002” – 2mm. Material – steel (СТ20).• Total thickness of Multilayer shield ≈ 350mm. Layer thickness: dNiFe. = 17-18mm; dCu. = 2-2,5mm.

Number of magnetic layers – 18; number of Cu layers –18.

0 200 400 600 800 100020

25

30

35

40

45

50

а

f, Hz

SE

(d

B)

Е~10 V/mSample "ТАСФ 735312.002"

"ТАСФ+Shield" "ТАСФ"

0 200 400 600 800 100020

25

30

35

40

45

50

55

60

65

70

75

b

Е~10 V/mSample "ТАСФ 745535.002"

"ТАСФ"

"ТАСФ+Shield"

f, Hz

SE

(d

B)

Application of multilayer films screens for protection of pulse electromagnetic radiation

(in cooperation with “Testpribor”, Moscow) rise time on levels 0,1-0,9; -0,5 and 5 nsec; pulse duration at 0,5-3 and 1000 nsec.

1. Образец №52. Образец №1

t, мкс50403020100

0.3

0.25

0.2

0.15

0.1

0.05

0

-0.05

-0.1

Н, А/м

Magnetic field strength of pulse radiation in protected area for screens №1 и №5

(5 нс; 1000 nsec)

№ Structure ofNiFe/Cu screen

5 nsec; 1000 nsec 0.5 nsec; 3 nsec

Кн, dB КЕ, dB

Кн, dB

КЕ, dB

~100 КHz

>1МHz

1 10х5mm/9х2,5mm

~85 >90 >74 >82 >65

2 50mm/0

~61 >90 >74 >82 >65

3 15mm/0

~59 >85 >74 >82 >65

4 3х5mm/2х2,5mm

~63 >85 >74 >82 >65

5 0/0 ~55 >75 >74 >82 >65

Attenuation coefficients of pulse EMR for screens

Application of multilayer films screens for electromagnetic compatibility of blocks for aircraft and space equipment

(in cooperation with SRI RAN, Moscow)

Device for scan the spacecraft (linear stepper motor with multilayer screen)

Measurement of the amplitude-frequency characteristics of electromagnetic radiation of a linear stepper motor

Amplitude-frequency characteristics (AFC) of electromagnetic radiation of a linear stepper motor

AFC without screen AFC with screen

1. It has been developed technological process that allows to produce multilayer electromagnetic shields on standard metal blocks and housing of electronic equipment. These shields provide high efficiency of low-frequency EMR protection and high manufacturability of the process, good adhesive and the possibility of variation by the number and thickness of the partial layers in a wide range.

2. For protection of static magnetic fields most effective single-layer screens based on Ni 80Fe20 alloys with thickness 300-400 mm. Screens (the cylinder with diameter of 60 mm and a height of 100mm) characterized by shielding effectiveness 4 ÷ 10 (0,25 ÷ 2,0 Э) in the field 20 ÷ 160А/m; and 20 ÷ 36 (2,5 ÷ 25,0 Э) in the field 200 ÷ 2000А/m. It has been shown that for maximal shielding effectiveness we must take into account the basic magnetic characteristics of the screen material Bs, μmax and magnitude of the magnetic field corresponding to the maximum value of the magnetic permeability

3. Screens based on multilayer films structures provides higher level of LF EMR protection in comparison with industrial materials – Al, Cu, steel (CT20 and 3408). Shielding effectiveness of multilayer screens in the range 50-5000Hz is 100÷34 000. These values are in 20÷103 times higher than shielding effectiveness of screens based on industrial metal materials. Shielding effectiveness is a function of total screen thickness; number and thickness of magnetic layers.

4. Shields based on Ni80Fe20/Cu multilayer film structures at 100; 1000 and 10000 Hz are characterized by SE which in 2; 5 and 7 times higher than single-layered shields with the same chemical composition and total thickness. The most effective protection against LF EMR provides multilayer film structure with the maximal possible number of layers at the given thickness (close to value of the depth of EMR penetration).

CONCLUSIONS:

5. It has been investigated electric and magnetic component of pulsed EMR inside protected area (protection by screen). It is shown that at frequencies of 100 kHz MFS provides attenuation of the magnetic component is 85dB (for single-layer screen with the same chemical composition and thickness attenuation is 61dB). In frequency range higher 1MHz attenuation is more than 90dB.

CONCLUSIONS: