CA1282870C - Method of making metal printed circuit panels wherein circuitry thereon is connected to signal ground by means of mesas - Google Patents

Abstract

ABSTRACT

A unique housing (104) or a portable radio transceiver (100) is described that includes unique metal printed circuit panels providing for grounding and heat sinking of electrical components and circuitry thereon, and a battery as a structural element thereof. In one illustrated housing (104) three printed circuit panels (212, 213 and 214) and a stick battery (210) are held together by interlocking side rails (206, 207). The unique printed circuit panels (212, 213 and 214) include mesas (422) that protrude through corresponding holes in the dielectric and circuitry layers (404 and 405) laminated on the panel. The mesas (422) are preferably soldered to the circuitry layer of electrical components thereon. The shape and size of the mesas (422) can be varied to provide the desired grounding and/or heat sinking. The unique metal printed circuit panel of the present invention may be advantageously utilized in a variety of applications including battery-operated radio transceivers, such as, for example, cellular radiotelephone systems and trunked radio systems.

Description

32~3 METEIOD OF MP~I~G ~/ETAL PR~ED CIRCUIT PANELS W~EREIN
CIRCUITRY T~E~ECN IS C3:)NNECIrED 10 SI(~IAL GRI:)UND BY
MEANS OF MESAS
Backaround Art The present invention is generally related to radio 5 transceivers and more particularly related to an improved portable radio transceiv~r housing structurally supported by a battery.
In the prior art, batteries for portable radio transceivers were typically designed to be an appendaqe to or to ~e inserted into and removed from a receptacle in the portable transceiver housing. For example, the battery was often an appendage to a side of the portable radio transceiver housing (see U.S. design patent no.
D269873). However, none of the prior art portable radio 15 transceivers took advantage of the heat sinking, electrical shielding and structural characteristics of batteries.

Oblects and Summary of the Invention Accordingly, it is an object of the present invention to provide an improved electronic circuitry housing that takes advantage of the heat sinking, electrical shielding and structur~l characteristics of a battery.

It is an~ther ohj~t of the present invention to provide an i~proY~d el~ctronic circuitry housing including a battery that is a ~tructural element thereof.
It is another o~ject of the present invention to provide an improv~d, ligh~-weight electronic circuitry housing including ~ ~ttery that strengthens the housing, shields electrical components therein and sinks heat from electrical components therein.
It is yet an~ther ~bject of the present invention to provide an improved electronic circuitry housing including a battery that is a ~tructural element thereof, whereby the housing is stronger with the battery than without the battery~
Brie~ly described, the present invention encompasses an improved method of coupling electronic circuitry to a grounding surface of a metallic housing panel, said method comprising the steps; of producing a plurality of mes~s protruding from the grounding surface 2~ of the metallic housing panel, bonding a dielectric layer to the grounding surface of the metallic housing panel, said dielectric layer including a plurality of holes, and each of said mesas protruding through a corresponding one of said holes; bonding a circuitry layer to the dielectric layer, said circuitry layer including a plurality of holes, and each of said mesas protruding at least partially through a corresponding one of said holes; bonding electronic circuitry to said circuitry layer~ and coupling the electronic circuitry on the circui~ry layer to said plurality of mesas.
Brie~ Descri~tion o~_~h~_a~r3 Figure 1, with parts ~roken away, is a perspective view of a p~rt~le radi~ transceiver ~mbodying the present inventicn~
~igure 2 is ~n exploded perspective view of the housing of the p~rta~l2 radiD transceiver in Figur~ l.

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Figure 3 is an end view of the portable radio transceiver housing in Figure 2.
Figure 4 is a partial cross-sectional view of a printed circuit panel in the portable radio transceiver housing in Figure 2.
Figure 5 is an exploded perspective view of the end cap of the portable radio transceiver housing in Figure 2.
Figure 6 is a cross-sectional view of another portable radio transceiver housing embodying the present invention.
Figure 7 is a partial top view of the portabl~ radio transceiver in Figure 6.
Figure 8 is a perspective view of a surface-mount connector used to interconnect the three printed circuit panels in the portable radio transceiver housing in Figure 2.
Figure 9 is a cross-sectional view of the surface-mounk connector in Figure 8 as it may be used to interconnect the three printed circuit panels in the portable radio transceiver housing in Figure 2.

Detailed Description of the Preferred Embodiment In Figure 1, there is illustrated a perspective view of a portable radio transceiver 100 embodying the present invention. Transceiver lO0 includes an outer covering 102 preferably of compliant plastic and an inner shell or housing 104 preferably comprised of sheet metal.
Transceiver lO0 also includes keyboard 106, display 10~, speakar 110 and microphone port 112 for communicating in a radio system. Transceiver 100 may be advantageously utilized in a variety of radio systems, such as, for example, cellular radiotelephone systems and trunked radio systems.
Referring next ot Figure 2, there is illustrated an exploded perspective view of the housing 104 in the portable radio transceiver 100 in Figure 1. A stick battary 210 inserts into housing 104 and is a structural element thereof. The elements of housing 104 may be made of light-weight sheet metal since battery 210 contribut~s significantly to the structural strength of the housing. In the preferred embodiment of the present invention, battery 210 includes three to ~i~e individual cells which are stacked together as a stick.
~ousing 104 in Figure 2 includes three printed circuit panels 212, 213 and 214, a stick battsry 210, a battery tube 211, side rails 206 and 207 and end caps 202 and 203. In the preferred embodiment illustrated in Figure 2, panels 212, 213 and 214, side rails 206 and 207 and battery tube 211 are made of sheet metal, and the exterior portions of end caps 202 and 203 are made of plastic and metal. Panel 212 is the logic printed circuit panel and includes on one side keyboard 106 and display 108, and on the other side electronic circuitry, which performs the signalling and control functions of the portable transceiver 100. The electronic circuitry on each o~ the panels 212, 213 and 214 includes surface mountable electrical components 224 soldered to an elactrical circuitry layer, which toqether with a dielectric layer is laminated to panel 212 (shown in more detail in Figure 4).
Panel 213 in Figure 2 is the transmitter printed circuit panel and includes male connector 220 which interconnects panels 212, 213 and 214, and on one side elactronic cixcuitry, which is the radio frequency (RF) --5~

transmitter of the portable transceiver 100. Male connector 220 extends on both sides of panel 213 for coupling control, RF and audio signals by way of corresponding female connectors 222 and 223 between the transmitter circuitry, logic circuitry and receiver - circuitry (shown in more detail in Figures 8 and 9).
Panel 213 also includes two connecting pins 242 and 243 that couple transmitter and receiver RF signals to serpentine antenna that is located in end cap 203 (shown in more detail in Figure 3). Panel 213 has an I-beam cross-section for imparting strength to housing 104. One side of panel 213 inserts into a channel in battery tube 211 for structurally coupling panel 213 to battery 210.
In the preferred embodiment illustrated in Figure 2, battery 210 and tube 211 have canted sides 240 and 241 for resisting torsionally applied forces. These features of battery 210, tube 211 and panel 213 are illustrated in more detail in the cross sectional view in Figure 3.
Panel 214 in Figure 2 is the receiver printed circuit panel and includes on one side electronic circuitry, which is the RF receiver of the portable transceiver 100. Panel 214 includes flanges 226 and 232 which insert into slots 230 and 236 in end caps Z03 and 202, respectively, for positioning and retaining panel 214 in housing 104. Similarly, edges 227 and 233 of panel 213 insert into slots 231 and 237 in end caps 203 and 202, respectively, for positioning and retaining panel 213 in housing 104; and flanges 22~ and another flange (similar to flange 228 but not shown) which insert into slots 232 and 238 in end caps 203 and 202, respectively, for positioning and retaining panel 212 in housing 104. Once panels 212, 2~3 and 21~ in Figure 2 are positioned in end caps 202 and 203, side rails 206 and 207 may be slipped onto the edges of panels 212, 213 and 214 for completing assembly o~ housing 104. The elements of housing 104 are essentially held together by interlocking geometry which causes side rails 206 and 207 and panels 2~2, 213 and 214 to be one structure. End cap 202 includes a battery retaining tab (not shown) and metal plate 271 which has slots 236, 237 and 23g. Metal plate 271 is connected to end cap 202 by screws (not shown) or adhesive. End cap 203 (shown in more detail in Fi~ure 5) has an outer portion 270 which is connected to inner portion 269 by screws (not shown) or adhesive~
Once assembled, housing 104 is slipped into outer covering 102~ Thus, transceiver 100 may be ~uickly and easily assembled without using screws 268.
Referring next to Figure 3, there is illustrated an end view of housing 104 where end cap 203 has been removed. The center porkion 250 o~ side rail 207 is shaped to capture the flanged side 259 of panel 213. The center portion 251 of side rail 206 is shaped to fit over side 240 of battery tube 211. In other embodiments, center portion 25~ canted of side rail 206 may be shaped to capture cant2d side 240 of battery tube 211. Battery tube 211 includes side rails 261 shaped to captur~ the flanged side 258 of panel 213. Side rail 261 is attached by spot welding or other suitable means to canted side 241 of battery tube 211. Contacts 2~4 on battery 210 feed a DC voltage to the electronic circuitry by way of contacts on end cap 203 which in turn are coupled to leaf contacts ~not shown) that connect to corresponding pads on the transmikter circuitry on panel 213 when housin~
104 is assembled. Pins 242 and 243 coupled transmitter and receivar signals to an antenna located in end cap 203 (shown in more detail in Figure 5). Flanges 226 and 228 insert in~o slots 230 and 23~, respectively, in end cap 203 as explained hereinabove with respect to Figure 2.
The edges 244-247 of side rails 206 and 207 in Figure 3 include channels which slide in~o corresponding channels in the edges 252-255 of panels 212 and 214. The center portion 25Q of side rail 207 is also shaped to capture the I-beam side 259 of panel 213. According to a feature of the present invention, the edges 244-247 of side rails 206 and 207 are also shaped to exert a spring force on the edges 252-255 ~f panels 2~2 and 214 when housing 104 is assembled. Furthermore, panels 212, 213 and 214 are strengthened by battery 210 since battery 210 is a structural element of housing 104. As a result, panels 212l 213 and 214 may be made out of sheet metal.
The electronic circuitry on each of the panels 212, 213 and 214 is also illustrated in greater detail in Figure 3. The logic circuitry on panel 212 includes components 272 which, in the preferred embodiment, are soldered to an electrical circuitry layer, which together with a dielectric layer is laminated to panel 212 (shown in more detail in Figure 4). Similarly, the transmitter circuitry on panel 213 includes components 274, and the receiver circuitry on panel 214 includes components 273.
The components 272 on panel 212 are electrically shielded from the RF signals on panels 213 and 214 since panels 212, 213 and 214 are preferably made of sheet metal and are coupled to signal ground. Furthermore, large components such as component 273 on panel 214 and component 274 on panel 213 may be offset relative to one another such that they may have a vertical length slightly less than the vertical distance between panels 212 and 214.
Referring next to Figure 5, there is illustrated an ~f~

exploded perspective view of end cap 203 of the porta~le radio transceiver housing 104 in Figure 2. End cap 203 includes serpentine antenna therein for transmitting and receiviny ~F signals. End cap includes inner portion 269, outer portion 270 and cover 514. Inner portion 269 includes metal ground plane 502 and circuit board 504.
Circuit board 504 includes posts 506 and 507 which are coupled by stripline circuitry to receptacles 509 and 508, respectively. Outer portion 270 of end cap 203 includes a circuit board 518 having a serpentine loading circuit 512. The serpentine loading circuit 512 is formed by a zig-zag stripline. Pins 242 and 243 on panel 213 in Figure 2 insert into rsceptacles 509 and 508, respectively for connecting the transmitter and receiver circuitry to the antenna formed by posts 506 and 507 and serpentine loading circuitry 512. The foregoing antenna circuitry is described in more detail in U.S. Patent No.
4,571,595, issued February 18, 1986, entitled "Dual Band Transceiver Antenna: and invented by James P. Phillips and Henry L. Kazecki.
In Figure 4, there is illustrated a partial cross-sectional view of printed circuit panel 402 representative of printed circuit panals 212, 213 and 214 in the portable radio transceiver housing 104 in Figure 2. The representative printed circuit panel 402 in Figure 4 includes an electrical circuitry layer 406 and a dielectric layer 404 which are colaminated to panel 402.
Any suitable adhesive 410 may be utilized to laminate or bond dielectric layer 404 to panel 40~ and to bond electrical circuitry layer 406 to dielectric layer 404.
~lectrical circuitry layer 406 includes conductivP
plating 412 on the top and/or bottom surface thereof for pro~iding circuit paths for electrical signal continuity 2~
- 8a between such electrical components and connectors.
Components 432 are preferable surface mount components.

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Panel 402 in Figure 4 includes a plurality of mesas 422 which are indPntations extending up between corresponding holes in the dielectric layer 404 and 5 electrical cir~uitry layer 406. Mesas 422 protrude through corresponding holes in the dielectric layer 404 and at least partially through corresponding holes in electrical circuitry layer 406. Mesas 422 are preferably bonded by solder 408 to plating 412. In the preferred embodiment, mesas 422 have a height of approximately 0.20 inches and a diameter o~ 0.0~0 inches; metal panel ~02 has a thickness of 0.015 inches; dielectric circuitry layer has a thickness of 0.010 inches; and electrical circuitry layer has a thickness of 0.010 inches. Since panel 402 is preferably made of a conductive metal and ooupled to siynal gro~nd, mesas 422 couple signal ground to plating 412 on th~ top surface o~ layer 406.
Furthermore, stripline transmission lines 414 may be produced between grounded plating 412 and grounded metallic panel 404. Stripline transmission lines 414 may be used to provide signal paths in a high frequency circuit, such as those found in RF signal transmitters and receiversO Moreover, in addition to providing siynal ground connections, mesas 422 also provide paths for the trans~er of dissipated heat from an electrical component 432 on layer 406 to metal panPl 402. When mesas 422 are used for heat sinking purposes, the electrical component 432 dissipating the heat may be mounted at least partially on one or more mesas 422, and the mesas 422 may be elongated slots or rectangular indentations or may b2 indentations shaped to con~orm to a particular component.

Referring next to Figure 6, there is illustrated a cross-sectional view nf another portable radio transceiver housing 600 embodying the present invention.
-- 5 As shown in Figure 6, the ideal battery encompassing the present invention is a flat battery which also becomes a load-bearing surface of the housing 600. The battery walls are not only enclosures for one or ~ore cells but also a structural element of the housing.
Housing 600 in Figure 6 includes flat battery 602, a first U-shaped panel 604 and a second U-shaped panel 606.
U-shaped panel 604 has first and second side portions 651 and 662, respectively, and a center portion 663 having inner and outer surfaces. ~-shaped panel 606 has first and second side portions 671 and 672, respectively, and a center portion 673 having inner and outer surfaces.
Panels 604 and 606 each include electrical components 624 soldered to a circuitry layers 611 and 6~1, which is colaminated with dielectric layers 610 and 640 to inner surfaces of the center portions 663-673, respectively of panels 60~ and 606 by any suitable means. Colaminating circuitry layers 511 and 641 and dielectric layers 610 and 640 to inner surfaces of the center portions 663 and 673 of pallels 604 and 606 strengthens panels 604 and 606, thereby enhancing the structural integrity of housing 600. In other embodiments, circuitry layer 611 and dielectric layer 610 may be bonded by adhesives or other suitable means to panels 604 and 606. Connectors 631 and 632 provide for interconnection o~ electrlcal signals between panels 604 and 606, respectively. Although housing 600 is shown with two panels 604 and ~06, only one panel 605 ne~d be utilized in practicing the present invention.
Battery 602 in Figure 6 includes edges having channels 644 which mate with corresponding channels 642 in first and second side portions 661 and 662 of panel 604. Channels 642 and 644 extend khe entire length of battery 602 and panel 604, respectively. Housing 600 may be assembled by sliding battery 602 into panel 604.
Assembly is completed by adding end cap 650, such as caps 202 and 233 in Figure 2/ which end cap 650 maybe attached to battery 602 and panel 604 by scrsws, adhesive or other suitable means.
As can be seen form the partial top view of housing 600 in Figurs 7, battexy 602 is flat and has a length substantially the same as the overall length of housing ~00. According to an important feature of the present invention, if battery 602 is at least one-third as long as housing 600, battery 602 will be a structural element o~ housing 600. In other words, housing 600 is stronger with battery 602 th~n without it. When battery 602 has a length that is less than one-fourth that of housing 600, battery 602 becomes a load to housing S00 rather than a structural element. However, in such cases, battery 602 may also be a structural element of housing 600 if attached to other alements by kPy ways, screws, brackets, clamps or other suitable means.
For example, the stick battery 210 in Figure 2 likewise functions as a structural element of the housing since it picks up a significant portion of applied inertial and static loads. By means of the canted surfaces 240 and 241 of battery 210 in Figure 3, the torsional strength of the stick battery 210 is used to resist rotational torques applied along the length of housi~g 104 ~X-axis). Similarly, a torque about the Y-axis (width) or a load along the 2-axis (height) is resisted by canted surfaces 240 and 241, side rail 261 and battery tube 211 when sufficient deflection of tube 211 occurs for battery 210 to be loaded as a beam. A
load along the Y-axis is resisted by canted surfaces 240 and 241 and by battery 210 when tube ~11 is deflected such that it bears on battery 210.
Components 624 in Figure S dissipate varying amounts of heat during operation. Often only one or a few of the components 624 will dissipate a large fraction of the total power dissipated by the electronic apparatus in housing 600 producing a hot spot. Conventional methods minimize the effect of such hot spots by heat sinking such components to a heat spreader and adding to the housing thermal insulation, thereby forcing the internal volume of the housing to rise in temperature and hence equalize the outside sur~ace temperatur~ th~reof.
However, such conventional mathods are undesirable since additional weight and volume is required and higher temperatures are produced which reduce the reliability of the electronic circuitry.
Accordiny to the present invention, the thermal mass and heat conduction properties of battery 602 may be utilized to equali~e temparatures due to power dissipating within the housing 600 without adding additional mass. Since the lower surfac~ of battery 602 is adjacent to and in contact with panel 606, heat is conducted away from panel 606 by battery 602. Heat trallsfer can be enhanced by coating the adjoining surfa~es of battery 602 and panel ~06 with a suitable the~mally conductive ~ompound 683. Thus, in housing 600, components 624 dissipating large amounts of heat are preferably mounted on panel 606 such that battery 602 - 13 ~

absorbs,spreads and conducts away heat dissipated by such components 624.
A multi-cell battery, such as battery 602 in Figure 6 or battery 210 in Figure 2, may be implemented by two methods. In both methods, some form of liquid or gas tight cell enclosure is required to electro-chemically separate Pach sell from the other. First, a very weak or thin outer enclosure only sufficient to maintain the moisture of each cell could be provided around each electrode set thereof. Such cells would be installed into a battery tube or housing which provides the strength needed to contain the contents of the cells and also acts as a structural element of housing. Secondly, individual c lls may be provided with individually strong enclosures which when coupled together act as a structural element of housing.
Turning to Figure 8, there is illustra~ed a perspective view of a surface-mount connector ~00 used to interconnect two or more printed circuit panels, such as, for example, panels 212, 213 and 214 in the portable radio transceiver housing 104 in Figure 2. Connector 800 includes a plurality of pins 802 each coupled to a spring contact B04 and extending through plastic header 806.
Plastic header 806 includes portions 810 that insulate corresponding pins 802 from metal panel 213 ~shown in more detail in Figure 9).
Two different methods may be used to manufacture connector 800 in Fiyure 8. According to the first method, the contacts 804 are insert molded into the plastic header ~06 and pins 802 are press fit in place after molding is completed. The contacts 804 are produced on a "comb" with a slightl~ extruded hole into which the pins B02 with a cold-formed, bulged center - 13a -section can be pressed. This method relatively inexpensively provides a generic molded connector 800 that gets its identity a~ter the unique pin 802 is pressed in place. A high temperature plastic is used for header 806, and pins 802 can be produced by a low c03t cold heading process. According to a relatively more expensive second method, the pins 802 and spring contacts 804 are welded or high temperature soldered together and th~n insert molded into the plastic header 806 using a high temperature solder.

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Referring to Figure 9, there is illustrated a cross-sectional view of the surface-mount connector in Figure 8 as it may be used to interconnect the three printed 5 circuit panels in the portable radio transceivex housing in Figure 2. Three male connectors 912, 913 and 914 and three female connectors 902, 903 and 904 are shown.
Connectors 902, 903 and 904 are com~entional surface-mount female connectors each including a pair of contacts 920 and 921 for each pair of pins in connector 912. Connector 912 is surface mounted to panel213 and ~onnected to panel 212 by way of surface~mounted connector 902 and to panel 214 by way of surface-mounted connector gO3. Connector 914 is surface mounted to the topside tkeyboard, display and speaker side) of panel 212 and connected to the bottom side of panel 212 by way of surface~ mounted connector 904. As a result, the circuitry and dielectric layers on the top side of panel 212 may be removed for replacing the keyboard~ display and speaker assembly. Connector 913 is surface mounted to panel 214 for providing external contacts 925, which may be used to couple transceiver 100 ts an external speakerphone, power amplifier or other peripheral devices.
In summary, a unique portable radio transceiver housing has been described that includes a battery which is a structural element thereof. The battery not only strengthens the housing, but also provid~s shielding against electromagnetic radiation and sinking o~ heat dissipated by electrical components. Since the battery is a st:ructural element of the housing, the housing elements can be implemented with sheet metal to produce bol:h a light-weight and structurally strong housing. the portable radio transceiver housing of the present ~z~
- 15 ~

invention may be advantageously utilized in a variety of radio systems including battery-operated radio transceivers, such as, for example, cellular radiotelephone systems and trunked radio systems.
.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:

1. A method for coupling electronic circuitry to a grounded surface of a metallic housing panel, said method comprising the steps of:
producing a plurality of mesas protruding from the grounded surface of the metallic housing panel;
bonding a dielectric layer to the grounding surface of the metallic housing panel, said dielectric layer including a plurality of holes, and each of said mesas protruding through a corresponding one of said holes;
bonding a circuitry layer to the dielectric layer, said circuitry layer including a plurality of holes, and each of said mesas protruding at least partially through a corresponding one of said holes;
bonding electronic circuitry to said circuitry layer; and coupling the electronic circuitry on the circuitry layer to said plurality of mesas.

2. The method according to claim 1, wherein said electronic circuitry bonding step includes the step of bonding at least one surface-mount device to said circuitry layer.