Printed circuit board structure including a closed cavity
A printed circuit board can include a substrate layer, a first metal layer disposed over the substrate layer, a core layer disposed over the first metal layer, and a second metal layer disposed over the core layer, where the core layer defines a closed cavity between the first and second metal layers. Optionally, the cavity is filled with air and operates as an antenna.
1. A closed cavity printed circuit board comprising:
a substrate layer;
a first metal layer disposed over the substrate layer;
a core layer disposed over the first metal layer, and
a second metal layer disposed over the core layer, the core layer defining a closed cavity filled with air between the first and second metal layers, a circumferential side wall of the cavity defined by the core layer.
2. The printed circuit board of claim 1 further comprising a second core layer disposed over the second metal layer and a third metal layer disposed over the second core layer.
3. The printed circuit board of claim 2 wherein the third metal layer is a planar antenna.
4. The printed circuit board of claim 1 , wherein the second metal layer is part of a 2-layer board disposed on the core layer.
5. The printed circuit board of claim 1 further comprising a pair of adhesive layers between the core layer and the first and second metal layers, the pair of adhesive layers defining a top wall and a bottom wall of the cavity.
6. The printed circuit board of claim 5 wherein the adhesive layers include a low-flow adhesive.
7. A radiofrequency module comprising:
a printed circuit board including a substrate layer, a first metal layer disposed over the substrate layer, a core layer disposed over the first metal layer and defining a closed cavity filled with air, a circumferential side wall of the cavity defined by the core layer, a second metal layer disposed over the core layer, a second core layer disposed over the second metal layer and a third metal layer disposed over the second core layer, the third metal layer forming a planar antenna; and
one or more components configured to process radio frequency signals transmitted or received by the planar antenna.
8. The radiofrequency module of claim 7 further comprising a pair of adhesive layers between the core layer and the first and second metal layers, the pair of adhesive layers defining a top wall and a bottom wall of the cavity.
9. The radiofrequency module of claim 8 wherein the adhesive layers include a low-flow adhesive.
10. The radiofrequency module of claim 7 wherein the cavity defines an antenna.
11. A wireless mobile device comprising:
an antenna defined by a printed circuit board including a substrate layer, a first metal layer disposed over the substrate layer, a core layer disposed over the first metal layer and defining a closed cavity filled with air, a circumferential side wall of the cavity defined by the core layer, a second metal layer disposed over the core layer, a second core layer disposed over the second metal layer, and a third metal layer disposed over the second core layer, the cavity defining the antenna and configured to radiate in a first direction;
a planar antenna defined by the third metal layer and spaced apart from the cavity and configured to radiate in a second direction different than the first direction; and
a transceiver configured to process signals received by the antenna.
12. The wireless device of claim 11 further comprising a pair of adhesive layers between the core layer and the first and second metal layers, the pair of adhesive layers defining a top wall and a bottom wall of the cavity.
13. The wireless device of claim 12 wherein the adhesive layers include a low-flow adhesive.