2EMI屏蔽材料应用设计.ppt

2EMI屏蔽材料应用设计
常用屏蔽材料1:导电布( Fabric Over Foam: FOF)
Fibric +foam+ PSA or Clip
常用屏蔽材料2—导电泡棉(Conductive 受正压力
受单剪切力
受单剪切力/倒沟
受90压力
双向受的剪切力
EMI衬垫在安装条件下受力后的尺寸
H: 衬垫压后高度
W: 衬垫压后宽度
应用EMI衬垫考虑之 5 -塑性变形,无恢复变形
塑性变形,残余变形,无恢复变形(图例中)
=
= . 120
= 4%.
.120
.200
应用EMI衬垫考虑之 6 -SE
对比Qualitative Shielding EffectivenessFive Popular Gasket Types
120 ---

100 ---
80 ---
60 ---
40 ---
20 ---
0 ---
dB
| | | | | | |
10k 100k 1M 10M 100M 1G 10G
Frequency (Hz)
BeCu Metal Gaskets
BeCu Mesh Gaskets
BeCu
Fabric Over Foam Gaskets
Elastomer Gaskets
Monel Mesh Gaskets
应用EMI衬垫考虑之 7 - EMI衬垫的固定方法
卡扣
短缝
沟槽
双卡
压敏胶/导电胶
铆,焊,螺
SNAP-IN
WELD
RIVET
RITE TRAK®
SNAP-IN RIVET TRAK
CLIP-ON
OTHERS
SOLDER
SLOT MOUNT
PSA
-金属簧片 –安装
应用EMI衬垫考虑之 8: UL Rate
Laird Technologies FOF UL ratings driven by foam and adhesive layer
HB
80/20 Blend of TPE/DSM Foam w/ Polyethylene Adhesive
FR Urethane Foam w/ Polyester Adhesive
V0
100% DSM TPE Foam w/ Polyethylene Adhesive
FR Urethane Foam w/ FR Polyester Adhesive
对比Five Popular Gasket Types
Parameter
dB Falloff, 10k-10G
Variability
Compression Range
Closure Pressure
Usable in Shear
Compression Set
Flame Retardant
Fluid Seal
Surface Area
Weight
Gas Permeable
BeCu Finger
No
0 - 6 dB
20 - 80%,45
20 #/Lin Ft
0,3 kg/cm
Yes
None
Yes
No
Minimum
Light
No
BeCu Mesh
Yes (Hi Freq)
6 - 18 dB
15 - 75%,45
10 #/Lin Ft
0,15 kg/cm
No
None
Yes
No
Medium
Light
No
Monel Mesh
Yes (Hi Freq)
6 - 18 dB
5 - 15%,10
20 #/sq in
kg/sq cm
No
Medium
Yes
No
Maximum
Medium
No
Fabric o Foam
Yes (VHiFreq)
0 - 10 dB
20 - 60%,45
10 #/Lin Ft
0,15 kg/cm
Limited
Low
Yes
No
Medium
Light
Yes
Ag Filled Elast
Yes (LowFreq)
>40 - 60 dB
5 - 20