# US 5,703,544 A · RF printed circuit module and method of making same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,544 A - Document ID: US5703544A - Status: Granted - Kind: A - Application number: 08/615,653 - Filed: 1996-03-13 - Granted: 1997-12-30 - Earliest claimed: 1996-03-13 - Assignees: Ericsson Inc. - Inventors: William Witherspoon Hays III - Web page: https://patentgrep.com/patent/US5703544A ## CPC - H01P 1/20381: {Special shape resonators} - Y10T 29/49004: including measuring or testing of device or component part - H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention discloses an RF printed circuit module and the method of making it. The RF printed circuit module includes a first single-clad sheet having a dielectric layer and a metal layer attached to a top surface thereof, a second single-clad sheet having a dielectric layer and a metal layer attached to a bottom surface thereof, and a double-clad sheet having a dielectric layer with a first metal layer attached to a top surface and a second metal layer attached to a bottom surface, wherein the double-clad sheet is positioned between and attached to the first and second single-clad sheets. The first and second metal layers of the double-clad sheet are etched to form desired lumped and distributed circuit elements thereon. The metal layers of the first and second single-clad sheets are etched to provide ground planes and portions of external terminals for the RF printed circuit module. The RF printed circuit module is edge-plated along the perimeter thereof to connect the metal layers of the first and second single-clad sheets, with a portion of such edge-plating being removed on one side of the RF printed circuit module to form a pair of external terminals to permit electrical connection thereto by a surface mounting arrangement. ## Claims ### Claim 1 An electronic module for an RF device, comprising: (a) a first single-clad sheet including a dielectric layer having a metal layer attached to a top surface of said dielectric layer; (b) a second single-clad sheet including a dielectric layer having a metal layer attached to a bottom surface of said dielectric layer; (c) a double-clad sheet including a dielectric layer having a first metal layer attached to a top surface of said dielectric layer and a second metal layer attached to a bottom surface of said dielectric layer, wherein said first and second metal layers are etched to form desired lumped and distributed circuit elements, said double-clad sheet being positioned between and attached to said first and second single-clad sheets; (d) edge-plating along the perimeter of said electronic module connecting said metal layers of said first and second single-clad sheets; (e) a pair of external terminals brined on at least one side of said electronic module to permit electrical connection thereto by a surface mounting arrangement; and (f) an outer layer around said first single-clad sheet, said second single-clad sheet, and said double-clad sheet. ### Claim 2 (depends on 1) The electronic module of claim 1, wherein said electronic module is an RF bandpass filter. ### Claim 3 (depends on 1) The electronic module of claim 1, wherein said distributed circuit elements comprise stripline resonators. ### Claim 4 (depends on 3) The electronic module of claim 3, wherein said metal layers of said first and second single-clad sheets are etched to serve as ground planes for said stripline resonators. ### Claim 5 (depends on 1) The electronic module of claim 1, wherein said electronic module is an RF coupler. ### Claim 6 (depends on 1) The electronic module of claim 1, further comprising at least one plated via through said electronic module, wherein said metal layers of said first and second single-clad sheets are connected electrically to at least one of said first and second metal layers of said double-clad sheet. ### Claim 7 (depends on 1) The electronic module of claim 1, wherein at least one of said metal layers of said first and second single-clad sheets is etched to form external terminals isolated from ground planes etched onto said metal layers of said first and second single-clad sheets. ### Claim 8 (depends on 7) The electronic module of claim 7, wherein said external terminals are formed by removing said edge-plating from a portion of at least one side of said electronic module between metal layers of said first and second single-clad sheets. ### Claim 9 (depends on 1) The electronic module of claim 1, said external terminals extending between and onto at least one of said metal layers of said first and second single-clad sheets, wherein said external terminals are available on any of such sides of said electronic module for surface mounting. ### Claim 10 (depends on 9) The electronic module of claim 9, wherein said electronic module is mountable to a host circuit board in a configuration allowing a low profile with a maximum footprint. ### Claim 11 (depends on 9) The electronic module of claim 9, wherein said electronic module is mountable to a host circuit board in a configuration allowing a high profile with a minimum footprint. ### Claim 12 An electronic module for an RF device, comprising: (a) a first single-clad sheet including a dielectric layer having a metal layer attached to a top surface of said dielectric layer; (b) a second single-clad sheet including a dielectric layer having a metal layer attached to a bottom surface of said dielectric layer; (c) a double-clad sheet including a dielectric layer having a first metal layer attached to a top surface of said dielectric layer and a second metal layer attached to a bottom surface of said dielectric layer, wherein said first and second metal layers are etched to form desired lumped and distributed circuit elements, said lumped circuit elements comprising capacitive elements and said double-clad sheet being positioned between and attached to said first and second single-clad sheets; (d) edge-plating along the perimeter of said electronic module connecting said metal layers of said first and second single-clad sheets; and (c) a pair of external terminals formed on at least one side of said electronic module to permit electrical connection thereto by a surface mounting arrangement. ### Claim 13 (depends on 12) The electronic module of claim 12, wherein said metal layers of said first and second single-clad sheets are etched to serve as ground planes for said capacitive elements. ### Claim 14 (depends on 12) The electronic module of claim 12, said capacitive elements of said first and second metal layers of said double-clad sheet being sized and arranged so that changes in capacitance values are minimized during parallel shifts of one metal layer with respect to the other. ### Claim 15 A production panel, comprising: (a) a plurality of interconnecting divider/support strips; (b) a plurality of RF printed circuit module clusters arrayed in said production panel, said clusters including a plurality of RF printed circuit modules connected to said divider/support strips by means of support tabs; and (c) means for measuring the impedance of a transmission line located on said production panel. ### Claim 16 (depends on 15) The production panel of claim 15, said transmission line comprising a stripline formed on a metal layer attached to an inner dielectric layer of said production panel, wherein lamination of a plurality of dielectric and metal layers forming said RF printed circuit modules is monitored and controlled by maintaining the impedance of said stripline within a specified range. ### Claim 17 (depends on 15) The production panel of claim 15, said transmission line comprising a microstrip formed on a metal layer attached to an inner dielectric layer of said production panel, wherein etching of metal layers attached to said inner dielectric layer is monitored and controlled by maintaining the impedance of said microstrip within a specified range. ### Claim 18 A process for making an RF printed circuit module, comprising the following steps: (a) providing a double-clad sheet having a dielectric layer with a first metal layer attached to a to surface of said dielectric layer and a second metal layer attached to a bottom surface of said dielectric layer; (b) etching said first and second metal layers of said double-clad sheet in a specified pattern to form desired lumped and distributed circuit elements thereon; (c) attaching a first single-clad sheet to the top of said double-clad sheet, said first single-clad sheet having a dielectric layer and a metal layer attached to a top surface of said dielectric layer; (d) attaching a second single-clad sheet to the bottom of said double-clad sheet, said second single-clad sheet having a dielectric layer and a metal layer attached to a bottom surface of said dielectric layer; (e) edge-plating the periphery of said RF printed circuit module between said metal layers of said first and second single-clad sheets; (f) forming external terminals on at least one side of said RF printed circuit module to permit electrical connection thereto by a surface mounting arrangement; and (g) providing an outer layer around said first single-clad sheet, said second single-clad sheet, and said double-clad sheet. ### Claim 19 (depends on 18) The process of claim 18, further comprising the step of forming at least one via through said RF printed circuit module, wherein said metal layers of said first and second single-clad sheets are connected electrically to at least one of said first and second metal layers of said double-clad sheet. ### Claim 20 (depends on 18) The process of claim 18, further comprising the step of isolating said external terminals from said metal layers of said first and second single-clad sheets. ### Claim 21 (depends on 18) The process of claim 18, further comprising the step of isolating said external terminals from said edge-plating on at least one side of said RF printed circuit module. ### Claim 22 (depends on 18) The process of claim 18, further comprising the step of forming said lumped circuit elements on said first and second metal layers of said double-clad sheet so they are sized and arranged to minimize changes in capacitance values during parallel shifts of one metal layer with respect to the other. ### Claim 23 (depends on 18) The process of claim 18, wherein said lumped and distributed circuit elements are arranged to form an RF bandpass filter. ### Claim 24 (depends on 18) The process of claim 18, further comprising the step of extending said external terminals onto at least one of said metal layers of said first and second single-clad sheets, wherein said terminals are available on any of such sides of said RF printed circuit module for surface mounting. ### Claim 25 A process for making a plurality of RF printed circuit modules substantially simultaneously on a production panel, comprising the following steps; (a) providing a double-clad sheet having a dielectric layer with a first metal layer attached to a top surface of said dielectric layer and a second metal layer attached to bottom surface of said dielectric layer; (b) etching said first and second metal layers of said double-clad sheet in a specified pattern to form desired lumped and distributed circuit elements thereon; (c) attaching a second single-clad sheet to the top of said double-clad sheet, said first single-clad sheet having a dielectric layer and a metal layer attached to a top surface of said dielectric layer; (d) attaching a second single-clad sheet to the bottom of said double-clad sheet said second single-clad sheet having a dielectric layer and a metal layer attached to a bottom surface of said dielectric layer; (e) cutting slots into said production panel to establish the perimeter of each RF printed circuit module, wherein at least one support tab remains attaching each said RF printed circuit module to at least one of an adjacent RF printed circuit module or said production panel; (f) edge-plating the periphery of each said RF printed circuit module between said metal layers of said first and second single-clad sheets; and (g) forming external terminals on at least one side of each said RF printed circuit module to permit electrical connection thereto by a surface mounting arrangement. ### Claim 26 (depends on 25) The process of claim 25, further comprising the step of removing said support tab from each RF printed circuit module. ### Claim 27 (depends on 25) The process of claim 25, further comprising the steps of: (a) providing a microstrip transmission line on said production panel; (b) monitoring the impedance of said microstrip transmission line; and (c) adjusting the time and solution of said etchings on said first and second metal layers of said double-clad sheet to cause said impedance to fall within a specified target range. ### Claim 28 (depends on 25) The process of claim 25, further comprising the steps of: (a) providing a stripline on said production panel; (b) monitoring the impedance of said stripline; and (c) varying the thickness and dielectric constant of said double-clad sheet to cause said impedance to fall within a specified target range. ### Claim 29 An electronic module for an RF device, comprising: (a) a first single-clad sheet including a dielectric layer having a metal layer attached to a top surface of said dielectric layer; (b) a second single-clad sheet including a dielectric layer having a metal layer attached to a bottom surface of said dielectric layer; and (c) a double-clad sheet including a dielectric layer having a first metal layer attached to a top surface of said dielectric layer and a second metal layer attached to a bottom surface of said dielectric layer, wherein a first set of capacitor plates are etched onto said first metal layer of said double-clad sheet and a second set of capacitor plates are etched onto said second metal layer of said double-clad sheet, said double-clad sheet being positioned between and attached to said first and second single-clad sheets; wherein said first and second sets of capacitor plates of said first and second metal layers of said double-clad sheet are sized and arranged so that at least some of the capacitor plates of said first set extend past the capacitor plates of said second set in a first direction and at least some of the capacitor plates of said second set extend past the capacitor plates of said first set in a second direction substantially perpendicular to said first direction, whereby changes in capacitance values are minimized during parallel shifts of one metal layer with respect to the other. ### Claim 30 (depends on 29) The electronic module of claim 29, further comprising edge-plating along the perimeter of said electronic module connecting said metal layers of said first and second single-clad sheets. ### Claim 31 (depends on 30) The electronic module of claim 30, further comprising at least one plated via through said electronic module, wherein said metal layers of said first and second single-clad sheets are connected electrically to at least one of said first and second metal layers of said double-clad sheet. ### Claim 32 (depends on 29) The electronic module of claim 29, further comprising a pair of external terminals formed on at least one side of said electronic module to permit electrical connection thereto by a surface mounting arrangement. ### Claim 33 (depends on 32) The electronic module of claim 32, said external terminals extending between and onto at least one of said metal layers of said first and second single-clad sheets, wherein said external terminals are available on any of such sides of said electronic module for surface mounting. ### Claim 34 (depends on 29) The electronic module of claim 29, wherein said metal layers of said first and second single-clad sheets are etched to serve as ground planes for said capacitive elements. ### Claim 35 (depends on 34) The electronic module of claim 34, wherein at least one of said metal layers of said first and second single-clad sheets is etched to form external terminals isolated from ground planes etched onto said metal layers of said first and second single-clad sheets. ### Claim 36 (depends on 29) The electronic module of claim 29, further comprising an outer layer around said first single-clad sheet, said second single-clad sheet, and said double-clad sheet.