Ceramic filter with differential conductivity
View Patent ↗The present application is directed to a filter and methods of making the same. The filter includes a block of dielectric material with a top surface including a patterned region, a bottom surface, and side surfaces. The filter also includes a through-hole extending through the block from the top surface to the bottom surface. The through-hole is partially surrounded by the patterned region. The filter also includes a wall extending from the top surface, the wall having an inner surface, an outer surface, and a roof. The bottom surface, side surfaces, outer surface, and roof have a first coating of silver and glass frit. The patterned region, through-hole and inner surface have a second coating of silver and glass frit. The glass frit in the first coating is at least 0.5% greater than the glass frit in the second coating. The application is also directed to a system including a printed circuit board and a filter.
1. A filter comprising:
a block of dielectric material with a top surface including a patterned region, a bottom surface, and side surfaces;
a through-hole extending through the block from the top surface to the bottom surface, the through-hole being partially surrounded by the patterned region; and
a wall extending from the top surface, the wall having an inner surface, an outer surface, and a roof, wherein
the bottom surface, side surfaces, outer surface, and roof have a first coating including glass frit,
the patterned region, through-hole and inner surface have a second coating including glass frit, and
the glass frit in the first coating is at least 20% greater than the glass frit in the second coating.
2. The filter of claim 1 , wherein the glass frit in the first coating is at least 30% greater than the glass frit in the second coating.
3. The filter of claim 2 , wherein the glass frit in the first coating is at least 40% greater than the glass frit in the second coating.
4. The filter of claim 1 , wherein the wall extends along a perimeter of the top surface.
5. The filter of claim 4 , wherein the wall includes a slot extending there through from the inner surface to the outer surface.
6. The filter of claim 5 , wherein the wall includes a post formed between the slot and a second, spaced-apart slot extending from the inner surface to the outer surface.
7. The filter of claim 6 , wherein a second post and the post are located on a similar side surface of the block.
8. The filter of claim 6 , wherein the patterned region of the top surface continuously extends to the post.
9. The filter of claim 1 , wherein a cavity is defined by the top surface and the wall.
10. A duplex filter comprising at least two filters according to claim 1 .
11. A system comprising:
a printed circuit board having a top surface and including input and output pads; and
a filter including:
a block of dielectric material with a top surface including a patterned region, a bottom surface, and side surfaces,
a through-hole extending through the block from the top surface to the bottom surface, and
a wall extending from the top surface, the wall having an inner surface, an outer surface, and a roof, the wall including a first post formed between two spaced-apart slots extending from the inner surface to the outer surface, and a second post formed between two other spaced-apart slots extending from the inner surface to the outer surface, wherein
the bottom surface, side surfaces, outer surface and roof have a first coating of silver and glass frit,
the patterned region, through-hole and inner surface have a second coating of silver and glass frit, and
the first and second coatings have different compositions.
12. The system of claim 11 , wherein the glass frit in the first coating is at least 20% greater than the glass frit in the second coating.
13. The system of claim 11 , wherein the input and output pads of the printed circuit board contact the first and second posts.
14. The system of claim 13 , wherein the roof is coupled to the top surface of the printed circuit board.
15. The system of claim 11 , wherein the through-hole is partially surrounded by the patterned region.
16. A method of patterning a filter comprising:
providing a dielectric block filter including a top surface, a bottom surface, side surfaces, a through-hole extending through the block filter from the top surface to the bottom surface, and a wall extending from the top surface, the wall having an inner surface, an outer surface, and a roof;
masking the top surface, through-hole, and inner surface of the wall;
depositing a first coating including glass frit and silver on the side surfaces, outer surface and roof;
masking side surfaces, outer surface and roof;
depositing a second coating including glass frit and silver on the top surface, through-hole, and inner surface of the wall; and
etching the second coating deposited on the top surface such that an area entirely surrounding the through-hole includes the second coating,
wherein the glass frit in the first coating is at least 20% greater than the glass frit in the second coating.
17. The method of claim 16 , wherein
the wall includes two spaced-apart slots extending there through from the inner surface to the outer surface,
the wall includes a post formed between the two spaced-apart slots, and
the top surface includes a second area outside the area with the deposited second coating, and continuously extends to the post.
18. The method of claim 17 , further comprising:
coupling the roof to a top surface of a printed circuit board; and
coupling the post to a pad on the top surface of the printed circuit board.
19. The method of claim 16 , wherein the glass frit in the first coating is at least 30% greater than the glass frit in the second coating.
20. The method of claim 19 , wherein the glass frit in the first coating is at least 40% greater than the glass frit in the second coating.