Flame retardant EMI shields
View Patent ↗An electromagnetic interference shield generally includes a resilient core member and an electrically conductive layer. An adhesive bonds the electrically conductive layer to the resilient core member. The adhesive can include halogen-free flame retardant. The electrically conductive layer can be provided with halogen-free flame retardant and/or a corrosion inhibitor.
1. An electromagnetic interference (EMI) shield comprising at least one resilient core member, at least one electrically conductive layer, and at least one adhesive bonding the electrically conductive layer to the resilient core member with a bond strength of at least ten ounces per inch width, the adhesive being free of halogen and including 25 percent or more by dry weight of at least one halogen-free flame retardant, the shield having a flame rating of V0 under Underwriter's Laboratories (UL) Standard No. 94, wherein the electrically conductive layer comprises at least one fabric material, and wherein the resilient core member comprises at least one urethane foam material that is free of flame retardant.
2. The shield of claim 1 , wherein the adhesive includes about 50 percent or more by dry weight of halogen-free flame retardant.
3. The shield of claim 2 , wherein the adhesive includes between about 50 percent and about 70 percent by dry weight of halogen-free flame retardant.
4. The shield of claim 3 , wherein the adhesive includes about fifty percent by dry weight of halogen-free flame retardant.
5. The shield of claim 3 , wherein the adhesive includes about sixty-three percent by dry weight of halogen-free flame retardant.
6. The shield of claim 3 , wherein the adhesive includes about fifty-five percent by dry weight of halogen-free flame retardant.
7. The shield of claim 1 , wherein the amount of halogen-free flame retardant within the adhesive is within a range of about fifty percent to sixty-three percent by dry weight of halogen-free flame retardant.
8. The shield of claim 1 , wherein the adhesive includes at least one halogen-free phosphorous-based flame retardant.
9. The shield of claim 1 , further comprising halogen-free flame retardant and urethane provided to the electrically conductive layer, and wherein the weight pick-up from the halogen-free flame retardant and urethane is between about 0.16 ounces per square yard and about 0.33 ounces per square yard.
10. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer, and that comprises about fifty-four percent by dry weight of a phosphorous-based flame retardant and about forty-six percent by dry weight of urethane.
11. The shield of claim 1 , further comprising halogen-free flame retardant and urethane provided to the electrically conductive layer, and wherein the weight pick-up from the halogen-free flame retardant and urethane is about 0.27 ounces per square yard.
12. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer, the halogen-free flame retardant comprising urethane and a corrosion inhibitor, and wherein the weight pick-up from the halogen-free flame retardant including the urethane and the corrosion inhibitor is between about 0.05 ounces per square yard and about 0.35 ounces per square yard.
13. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer, the halogen-free flame retardant comprising urethane and a corrosion inhibitor, and wherein the weight pick-up from the halogen-free flame retardant including the urethane and the corrosion inhibitor is about 0.15 ounces per square yard.
14. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer, the halogen-free flame retardant comprising about four percent by dry weight of a corrosion inhibitor and about ninety-six percent by dry weight of urethane.
15. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer, and wherein the electrically conductive layer has a surface resistivity of less than 0.1 ohms/sq.
16. The shield of claim 1 , further comprising halogen-free flame retardant provided to the electrically conductive layer.
17. The shield of claim 1 , wherein the adhesive comprises between 25 percent and about 70 percent by dry weight of halogen-free flame retardant.
18. The shield of claim 1 , wherein the shield has only three layers, consisting only of:
a first layer that includes the at least one resilient core member; and
a second layer that includes the at least one adhesive having the halogen-free flame retardant; and
a third layer that includes the at least one electrically conductive layer.
19. The shield of claim 18 , wherein the at least one electrically conductive layer includes a urethane coating.
20. The shield of claim 1 , wherein:
the at least one urethane foam material comprises polyurethane foam;
the at least one adhesive comprises at least one halogen-free phosphorus-based flame retardant, and a polyester adhesive layer which includes the halogen-free phosphorus-based flame retardant; and
the at least one fabric material comprises a metalized fabric laminated to the polyester adhesive layer.
21. A fabric-over-foam electromagnetic interference (EMI) shielding gasket comprising at least one resilient core member, at least one electrically conductive layer, and at least one adhesive bonding the electrically conductive layer to the resilient core member, the adhesive being free of halogen and including an amount of halogen-free flame retardant within a range of about fifty percent to about seventy percent by dry weight, the shield having a flame rating of V0 under Underwriter's Laboratories (UL) Standard No. 94, wherein the adhesive bonds the electrical conductive layer to the resilient core member with a bond strength of at least ten ounces per inch width, wherein the electrically conductive layer comprises at least one fabric material, and wherein the resilient core member comprises at least one urethane foam material that is free of flame retardant.
22. The gasket of claim 21 , wherein the adhesive includes about fifty percent by dry weight of halogen-free flame retardant.
23. The gasket of claim 21 , further comprising halogen-free flame retardant provided to the electrically conductive layer.
24. The gasket of claim 23 , wherein the halogen-free flame retardant provided to the electrically conductive layer is a corrosion inhibitor.
25. The shield of claim 21 , wherein the shield has only three layers, consisting only of:
a first layer that includes the at least one resilient core member; and
a second layer that includes the at least one adhesive having the halogen-free flame retardant; and
a third layer that includes the at least one electrically conductive layer.
26. The shield of claim 25 , wherein the at least one electrically conductive layer includes a urethane coating.
27. The gasket of claim 21 , wherein:
the at least one urethane foam material comprises polyurethane foam;
the at least one adhesive comprises at least one halogen-free phosphorus-based flame retardant, and a polyester adhesive layer which includes the halogen-free phosphorus-based flame retardant; and
the at least one fabric material comprises a metalized fabric laminated to the polyester adhesive layer.
28. An electromagnetic interference (EMI) shield comprising at least one resilient core member, at least one electrically conductive layer, and at least one adhesive bonding the electrically conductive layer to the resilient core member with a bond strength of at least 10 ounces per inch width, wherein the adhesive is free of halogen and includes an amount of halogen-free flame retardant that is not more than 70 percent by dry weight, the shield having a flame rating of V0 under Underwriter's Laboratories (UL) Standard No. 94, wherein the electrically conductive layer comprises at least one fabric material, and wherein the resilient core member comprises at least one urethane foam material that is free of flame retardant.
29. The shield of claim 28 , further comprising halogen-free flame retardant provided to the electrically conductive layer.
30. The shield of claim 28 , wherein the shield has only three layers, consisting only of:
a first layer that includes the at least one resilient core member; and
a second layer that includes the at least one adhesive having the halogen-free flame retardant; and
a third layer that includes the at least one electrically conductive layer.
31. The shield of claim 30 , wherein the at least one electrically conductive layer includes a urethane coating.
32. The shield of claim 28 , wherein:
the at least one urethane foam material comprises polyurethane foam;
the at least one adhesive comprises at least one halogen-free phosphorus-based flame retardant, and a polyester adhesive layer which includes the halogen-free phosphorus-based flame retardant; and
the at least one fabric material comprises a metalized fabric laminated to the polyester adhesive layer.
33. An electromagnetic interference (EMI) shield comprising at least one resilient core member, at least one electrically conductive layer, and at least one adhesive bonding the electrically conductive layer to the resilient core member, the adhesive being free of halogen and including halogen-free flame retardant in an amount within a range of about 50 percent by dry weight and about 63 percent by dry weight, such that the shield has a flame rating of V0 under Underwriter's Laboratories (UL) Standard No. 94, and such that the adhesive has a bond strength of at least 10 ounces per inch width, and wherein the electrically conductive layer comprises at least one fabric material, and wherein the resilient core member comprises at least one urethane foam material that is free of flame retardant.
34. The shield of claim 33 , wherein the shield is substantially free of halogen.
35. The shield of claim 33 , wherein the shield is entirely free of halogen.
36. An electronic device including the shield of claim 33 .
37. The shield of claim 33 , wherein the shield has only three layers, consisting only of:
a first layer that includes the at least one resilient core member; and
a second layer that includes the at least one adhesive having the halogen-free flame retardant; and
a third layer that includes the at least one electrically conductive layer.
38. The shield of claim 37 , wherein the at least one electrically conductive layer includes a urethane coating.
39. The shield of claim 33 , wherein:
the at least one urethane foam material comprises polyurethane foam;
the at least one adhesive comprises at least one halogen-free phosphorus-based flame retardant, and a polyester adhesive layer which includes the halogen-free phosphorus-based flame retardant; and
the at least one fabric material comprises a metalized fabric laminated to the polyester adhesive layer.