Aluminum EMI / RF Shield
A shield made from aluminum (AL) or an aluminum-based alloy coated with a solderable plating such as nickel or tin provides thermal improvement over existing shielding materials. The shield for circuitry on a circuit board comprising an aluminum material plated with a solderable material, the shield providing electromagnetic interference and radio frequency interference shielding and heat transfer when positioned over a circuit.
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This application is a Continuation Application of, and claims priority to U.S. patent application Ser. No. 14/210,561 filed on Mar. 14, 2014, which claims priority to U.S. Provisional Patent Application No. 61/788,151 filed on Mar. 15, 2013, the entire contents of each of which are hereby incorporated by reference.
BACKGROUND1. Field
The present disclosure relates to an EMI/RF shield for circuitry on a circuit board and more particularly an EMI/RF shield comprised of aluminum or an aluminum-based alloy and plated with a solderable material.
2. Related Art
Traditional EMI/RF shielding materials include but are not limited to nickel silver, tin plated cold rolled steel or SPTE, stainless steel, brass, or phosphor bronze materials which are good for formability and EMI/RF shielding but are poor from a thermal performance perspective or cost prohibitive for a shielding application.
One piece shields are typically used on thin devices where the height is a concern and replaceable lids cannot be used due to height restrictions. One piece shields are also used for cost saving solutions when compared to two piece shields. Two piece shielding solutions are generally used for reworkability and are typically higher cost.
SUMMARYA shield made from aluminum (AL) or an aluminum-based alloy coated with a solderable plating such as nickel or tin provides thermal improvement over existing shielding materials. Plated aluminum offers enhanced thermal performance while also offering a significant weight reduction when compared to commonly used shielding materials. Aluminum in its raw form is not a solderable material but can be post-processed with a solderable plating allowing the shield to be soldered directly to a circuit board. The aluminum-based shield helps spread heat generated from a device (IC) across the top surface of the EMI lid flattening out “hot spots.” Due to the higher thermal conductivity of aluminum and the ability to solder the shield directly to the board, the shield will also transfer heat from the top surface down the shield side walls and “dump” the heat into the circuit board. Circuit boards constructed using layers of copper traces will transfer heat away from the device offering a lower operating temperature improving device life and reliability.
The foregoing features will be apparent from the following Detailed Description, taken in connection with the accompanying drawings, in which:
An EMI/RF shield is made of aluminum or an aluminum-based alloy to take advantage of the thermal performance of aluminum. To allow for soldering, the aluminum material is plated with a solderable material such as nickel or tin.
The shield can be attached to the fencing in any way known in the art, such as by soldering. The attachment can be snap down or as otherwise know in the art. The shields 10 include top wall 20 and side walls 30. The shields lids 10 are made of an aluminum or aluminum-based alloy plated with a solderable material such as nickel or tin. The fence 9 can be made of aluminum or an aluminum-based alloy plated with a solderable material such as nickel or tin to permit soldering of the shield. The aluminum containing shields disclosed herein can be manufactured in accordance with what is known in the art in connection with manufacturing shields of conventional shielding materials. The aluminum material can be plated with nickel, tin or another solderable material before or after being formed into a lid configuration.
The shield 310 includes a top wall 320 and may include side walls 330. The shield 310 is attached to fence 9 on a circuit board. Fins 340 include a series of valleys 342 wherein the fins 340 can be soldered to the top wall 320, a plurality of upstanding walls 344 and a plurality of top surfaces 346 which interconnect adjacent upstanding walls 344. As shown, the upstanding walls 344 of fins 340 can be configured to extend from the top wall at an angle other than a right angle from the top wall 320. Further, upstanding walls 344 may include further heat dissipation features such as additional fins 348.
The shields disclosed herein can be: single piece shields that are non-peelable or non-reworkable; single piece shields that are peelable/reworkable; two piece shields including a fence and lid both made using plated aluminum; two piece shields including a fence and lid, one component of which is plated aluminum (typically the lid) (the fence could use nickel silver, cold rolled steel or plated stainless steel); and two piece shields with soldered pre- or post-plated aluminum or copper (not limited to material selection) fin stock soldered to plated lid surface.
Low profile/low power devices such as mobile handsets, tablets, thin laptops may use either a one or two piece shield solution without soldered fin stock to the lid offering a thermal advantage over commonly used nickel silver and cold rolled shields.
High power applications such as RF modules, processor modules which typically are found in larger case structures (e.g. server chassis, wireless modems, set top boxes or cable boxes) which are typically force convection cooled. These devices can use plated fin stock to offer additional thermal improvement when used with the base plated aluminum fence and lid. Fin stock (formed, folded, stamped, etc.) is soldered to the top surface of the EMI/RF shield lid increasing thermal performance.
Having thus described the disclosure in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. It will be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure. What is desired to be protected is set forth in the following claims.
Claims
1. A two piece shield attached to a circuit board for providing electromagnetic interference and radio frequency interference shielding and heat transfer when positioned over a circuit, comprising:
- a fence made of a first material, the fence attachable to a circuit board; and
- a lid attached to the fence, the lid made of a second material.
2. The two piece shield of claim 1, wherein the first material is nickel silver.
3. The two piece shield of claim 1, wherein the second material is aluminum.
4. The two piece shield of claim 3, wherein the second material is plated with nickel.
5. The two piece shield of claim 3, wherein the second material is plated with copper.
6. The two piece shield of claim 3, wherein the second material is plated with tin.
7. The two piece shield of claim 1, wherein the lid is snapped on to the fence.
8. The two piece shield of claim 1, wherein the shield comprises a top wall and one or more side walls.
9. The two piece shield of claim 6, further comprising heat dissipating fins attached to the top wall of the shield.
10. The two piece shield of claim 1, wherein the shield is peelable.
11. The two piece shield of claim 1, wherein the shield is non-peelable.
12. A circuit shield assembly comprising:
- a circuit board including circuitry thereon;
- a two piece shield including a fence and a lid, the fence and lid containing aluminum plated with a solderable material, the fence attached to the circuit board enclosing at least a portion of the circuitry, the two piece shield transferring heat generated by the circuitry.
13. The two piece shield of claim 12, wherein the aluminum comprises an aluminum based alloy.
14. The two piece shield of claim 12, wherein the solderable material comprises at least one of nickel, copper, and tin.
15. The two piece shield of claim 14, wherein the shield further comprises heat dissipating fins attached to the top wall.
16. The two piece shield of claim 12, wherein the shield is peelable.
17. The two piece shield of claim 12, wherein the shield is non-peelable.
Type: Application
Filed: Jun 10, 2015
Publication Date: Oct 1, 2015
Applicant: A.K. Stamping Company, Inc. (Mountainside, NJ)
Inventors: Arthur Kurz (New Vernon, NJ), Michael Schneider (Montgomery, NJ), Bret Barry (Fincastle, VA)
Application Number: 14/735,437