Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a fluid tempera-
ture sensor and more speciflcally t~ a fluid temperature sensor
of the semiconductor type having a high sur~ace area to mass
ratio ~or the temperature sensing assem~ly thereby provid1n9 an
extremely fast acting temperature sensing unit.
2. Description of the Prior Art ~ ~`
As described above, the present lnvention relatss to
a temperature sensor which will provide a fast response device
suitable for use in control systems where a rapld t2mperature
..
sensing of a flowin~ fluid media is required. A typical use of -
such a temperature sensor would be in conjunction with the air
induction system in an automotive engine wherein the air tempera~
ture is utilized in conjunct~on with other en~ine parameters for
controlling the fuel in a fuel management syste~. ~
There are devices presently on the market which are ~ ;
similar to that which is to be described, but do not provide
the extremely fast temperature response associated wlth the
sensor of the present invention. In the temperature sensors
presently being manufactured, for example by the Texas Instru-
ments Corporation, the temperature sensin~ element is a silicon
chip semiconductor which is doped by various impurities to
control the resistance of the chip in response to variations in
temperature. The silicon semiconductor chips are sized as blocks
of approxlmately .015 x .015 x .006 inch dimension, the blocks
being bonded to a metal plate on one side and a gold w~re attached
to the opposite side of the chip in typical semiconductor manufac- ;
turing fashion. The chip is then bonded to a metallic frame which
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- is used as the base of the device, which frame i5 approximately
500 times the rnass of the silicon chip. The entire assembly is
then encased in a plastic moldin~ for handling and lnstallation
strength.
The metallic frame utilized as the base o~ the device
is of a thick cross-sectional area and relatively short in length
thereby providing a low surface area to mass ratio. Further, the
plastic incapsulant which has been made a strUctural part of the
device has a low thermal conductivity compare~ to metal and thus
lG impedes the flow of heat to or from the silicon chip. This incap-
sulant has been utilized due to the structural design of the
assembly.
Co-pending Canadian application 317,292 filed
December 4, 1978, commonly assigned, discloses a fast
response fluid temperature sensor wherein a semiconductor device
ismounted on a relatively flat fin which is open on both sides to
the fluid being sensed. In order to facilitate the connection of
the silicon chip to the exterior conductors, a pair of fins are
proYided, the fins being generally dish-shaped to ensure air flow ~
around the entirety of the assembly. -
However, with the air flow flowing around the entire
assembly, it is possible that, under certain circumstances, contami~
nants and other foreign material may cause damage to the chip and/or
lead attached to the chip. The present invention desrribes a
method of overcoming this problem.
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SUI~MARY OF THE INVENTlON
It has been found that the dynamic perfor~ance of a
sem;conductor type temperature sensor can be max;mized if the
rnass of the semiconductor chlp utilized in conjunction with
sensors of this type is minimized and is bonded to a metallic
fin ha~ing a large area relative to the mass of the fln and
semiconductor chip assembly. In a preferre~ embodiment, ~he
connection to one terminal of the serniconductor chip is achieved
by conductively bondin~ the chip to the metallic fin and providing
a second lead to the edge of the fin by various techniques to be ;
described hereinafter.
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The metallic fin should be arranged so that the ~luid
flow of the fluid being sensed is parallel to the fin or in maximum
heat transfer therewith. As will be shown, the temperature response ; ~-
of a thin. constant thickness ~etallic fin emersed in a fluid is
,
primarily a function of the surface area to mass ratio of the fin. ` ~`
In accordance with the present invention there is
provided a bemperature sensor for sensing the temperature of
a fluid ccmprising a base ~ember, fin means formed of a thin
disc havqng a high surface area to mass ratio mounted in fixed
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relationship to the base m~mber whereby the fluid to be sensed
may -flow over the fin means, semicc)nductor means moun-ted c~
the fin means having the characteristics of changing resistance
with changes in te~perature, a first output conductor connected
to the fin means, a second autput conductor electrically in~
sulated from the fin means and cc~nected to the surfaoe of
the chip remote from the surface of the chip in electrical
CDntaCt with the fin.
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Tt11JS, for a given material and independent of the size o~f the
fin, the temperature response tlme constant approaches ~ero
dS the thickness of the fin approaches zero in a theoretical
assembly .
For a practical assembly, the dens1ty and specific
heat also affect the time constant and both parameters have
been found to maximize the time response ~hen these parameters
are mininlized. Additionally, when the silicon chip is adcled
to the fin, the heat transfer between the fin and S~licon chip
beconles important. The thermal contact material between the
fin and chip must be of a high conductivity type, as for example
gold. Additionally, the heat tlow from the surrounding areas of
the fin relative to the area covered by the semiconductor chip
nlUS~ t mdxiflli~ed. Accordinyly, the thermal conductivity of the
fin becomes important and any material with high hea~ conductivity
(such as alurninum) is desirable.
Irl one embodiment of the invention the fin
i:, fdbiic~ed as a eirculdr, thin metallic disc with a semicon-
ductor chip mounted centrally of the edges of the disc. Theo-
retically, the fin should be fabricated of a tapering cross-sect~on,
the thickest portion of the cross-section being in the area wherein
the semiconductor chip is mounted, the fin taperin~ to zero
thickness at the periphery. In the practical embodiment of the
invelltiorl, the fin is supported at the periphery by various means
and the semiconductor chip is electrically bonded on the surface
of the chip but not in contact therewith.
It has been found tha-t the assembly which supports the
fin r;lust be such that heat flow to or from the support is minimized
since this heat flow does not necessarily result from the
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temperature of the fluld under consideratiun and, therefore,
the dynamic performance and the steady state temperature of
the semiconductor ehip maybe affected. St~ted otherwise,
a difference in temperat~re between the chip and the Fluid
media represents an error in the output signal and it ls ~his
error which sho~ld be minimized for any given instantan~ous
period of time. It is the desiratum of this invention to min~mize
the transient time to achieve stabjli~y between the temperature
of the chip and the te~perature of the fluid under consideration.
As stated above, one possible source af error
in this signal results from heat flow to or from ~he fin support.
Therefore, the fin support shollld be located at a point as
remote as possible fro~l the semiconductor chip and in the~;
pre~erred embodiment this support is establlshed at the outer
edge of the chip. Therefore, this necessity for a ~echanical
attachment prevents the outer edge of the chip from being
a theoretical ideal zero thickness. It has been found that
if the fin is of sufficient size in area, the radial Flow of heat
from the inner to outer or outer to inner port~on of the chip
~0 is essentially zero, and thus the heat flow due to the mechanical
support of the fin is minimized.
In this embodlment of th~ invent:Lon, the other ~:
terminal, other than the fin terminal, connected to the chip is
formed by providing a thin stripe of insulating material from
the outer edge of the fin radially inwardly to the semi-
conductor chip, up the side of the semiconductor chip and
slightly overlapping the top surface thereof. The lead wire,
ribbon or cond~cting film is then fabricated to conform to the
,
surface of the insulating stripe and extended Dn th~ top surface
of the chip beyond the lnsulating stri pe . Fi nally 9 a second thln
coat of insulating material ls appll e~ ~o the lead to encase
the lead from its end adjacent the bare upper surface ~f the
semiconductor chip across the fin to the nuter ed~ of the fin.
The insulating material may be any plastic adhesive
which satisfies the adheslve requirements of the fin and has an
el ectrical resi stance when in place for at least two orders of
magnitude greater than the resistance of the semiconductor
chip and is tolerant of the temperature and the environmental
conditions of the finished temperature sensor. ~ typical
material for automotive applications is the cyanoacrylate class
of adhesives such as marketed by the Eastman Corporation as
adhesive 910THT.
Since the lead wire and adhesive material described
above represent additional undesirable mass, the adhesive
insulating stripe should be of minimal thickness and $he wire
should he of minimal size to minimize the effect of this
additional mass on the dynamic and steady state perf~nance of
the sensor assembly.
In selecting suitable fin material the following relation-
ship is considered to be of significance in lnvestigating the
various characteristics of a material for its merit in conjunçtion
with use in connection with the present invention. For maximum
theoretical performance, the following relationship exists.
Mt = K where K - thermal conductivity,
bo) (Sp.Hp.~ ~= density, and
SP.HP, = specific heat
~he most desirable material l5 that which has pro~erties maxl-
mizin~ the term Mt. ln a practical applicat;on, other prDperties
such as cost fabricabil~ty, envirnnmental tolerance and avall-
ability may modify the material selection. In a modified form
of the invention it has been found that the heat transfer from
the fin to the chip maybe maximized and the apparent mass oF the ;;
assembly minimi~ed by contacting both sides of the chip with an
individual fin. Thus, each fin becomes one of the electrical
connections to the chip and the transfer of heat to and from the ~
fin, and thus the semiconductor chip, is made most efficient. It ;
is apparent that the fin ~ust be spaced a suFfic;ent distance to
prevent interference of the flow of the fluid under consideration
~*tween the fins, which interference would lower the heat transfer
between the fins and the fluid. As a modiFied form of the inven-
tion, it has been found that the fins could be fabricated of approxl-
mately a conical or disc shape with the apex of each disc electri-
rally connected to the opposite sides o~ the semiconductor chip.
With both fins attached to a support structure, a ~ery stiff . ~ :
mechanical structure is obtainable. ~
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Electrical connection to the fin or plural fins ~aybe
accomplished by providing electrically conducting supports for -
the fin or for the conductors in nonconducting supports. The
atlacl,l"~nt of ~he leads to the outer peripher maybe made by any
suitdble method siJch as soldering, weldin~, conductive adhesives,
or hy simple ~lechanical contact. An alternate lead and support
approach may be to prbvide integral support ar~s on the basic fin
stamping which maybe bent to a suitable shape to provide support
and cnrlYerlient electrical connection to the temperature sensing
body.
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As is readl'ly apparent, the fln or plura'lity of
fins maybe formed by die stampin~ methods and suitable radial
or clrcumferential ridges maybe provlded in the fins to enhance
structural ridig~ty. These fins may additlonally perform the
functlon of promoting boundary layer turbulence for better h~at
transfer between the fluid under considerat~on and the fin and
may also be utilized to provide a protective trough for lead
wires and insulation.
In a second em~odiment of th~ venti~n l;he f in
ls formed of a do~ed-shaped e'lement wh1~h ~s sealingly ~itted to
a multiple plastic member and the semiconductor chip ~s mounted
on the inside apex o~ the dome whereby the semiconductor chip and
any conductors leading to the chip or the domed fin will be fully
enclosed by the domed fin and the plastic molded member. In this
way the connections and the semiconductor chip are fully protected
from contaminants and mechanical injury due to foreign particles
striking either the leads or the semiconductor chip. As will~be :
noted from a further description of the device~ a foamed material
may ~e provided within the confined volume of the dome to further
protect the semiconductor chip and leads connected therewithO
Accordingly, it is one object of the present invention
to provide an improved fluid temperature sensing device.
It is another object of the present invention to provide ~-
improved ~emperature sensing device for a fluid having extremely
fast dynamic and steady state performance.
It is a further object of the present invention to pro-
vide an lmproved fluid temperature sensing device havin~ a high
surface area ~o mass ratio to enhance the transfer of heat from a
heat transfer deYice to the actual temperature sensin~ element.
It is another obiect of the present invention to provlde
an improved fluid temperature sensing device ~hich responds faster
than previous known temperature sensing devices by an order of
magnitude. -
It is still another object of the present invention to
provide an improved mountiny assembly for a temperature sensing
device wh1ch enhances the response time and steady stata perfor-
mance of the temperature sensor assembly.
It is a further object of the present invention to pro- ;
vide improved lead connection techniques for temperature sensing
assemblies incorporating assembly conductor chips for the sensin
element.
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l~ is still another object oF the present invention
to provide an improved temperature sensing assembly util~zing
a semiconductor chip which anhances the transfer of heat from
the fluid whose tempera~ure is being considered to the semicon-
ductor chip.
It is another object of ~he present inventlan to pro-
vide an impro~ed fluld temperature senslng assembly whlch is
inexpensive to manufacture, rel~able in operation and easily
installed.
Further objects, features and advantages of the present
invention will become more readily apparent upon a cons1deration
of the following specification when taken in conjunctlDn with the
attached drawings, in which:
BRIEF DESCRI~TION OF THE DRAWlNGS
Figure l is a sido view of a preferred form of the
fas-t response air temperature sensor incorporating certain
features of the present inventiorl;
Figure 2 is a top view of the a~r temperatur0 sensor
of Figure 1 and par~içularly illustrating the positioning of the
semiconductor chip and the interconnections between ~he output
leads and the semiconductor chip and fin;
Figure 3 is a cross-sectional view of the air tempera-
ture sensor of Figure 2 taken along lina 3-3 thereof;
Figure 4 is a cross-sectlonal view of the lnterconnec~ion
between the output conductor and the semiconduct~r chip of Figure
2 taken along line 4-4 thereof;
Figure 5 is a top view of a modified form o~ ~he fast
response temperature sensor of Flgure l;
Figure 6 is a partial cross-sectional view of the
modified air temperature sensor of Figure 5 taken along llne
6-6 thereof and particularly ~llustratlng a modlfied positlon
for the semiconductor chip and the ~nterconnection w1th the
output conductor;
Figure 7 is a cross-secti¢nal view similar to Figure
4 and particularly illustrating th~ intarconnection ~etween
the output conductor and the fin, the cross-sectional view
taken along line 7-7 of Figure 5;
Figure 8 is a top v1ew of another mod~f1ed form of
the fast response air temperature sensor of the present inven-
tion, partially broken away; ~ -
Figure 9 is a cross-sectional view of the modifled :~
air temperature sensor of Figure 8 taken along line 9-9 thereof;
Figure 10 is another cross-sect~onal view of the
modified air temperature sensor of Figure 8 taken along line
lO-lO thereof;
Figure 1l is a further modified air temperature sensor
utilizing certain other features of the present invention, th1s
figure being shown partially in section to illustrate the inter-
connection between the dual fins and the support members;
Figure 12 is a cross-sectional view of a further :
modification of the ai~ temperat~re sensor of the present :
invention and particularly illustrating another type of inter-
connection between the output conductors and the ~in and semi-
conductor chip;
Figure 13 is a cross-sectional view of another modified
form of the present invention and partieularly Illustrating a
modification of the interconnections between the output conductors
and the fin and semiconductor chipi
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Figure 14 is a bottom view of the semiconductor chip,
thin and interconnection assembly of Figure 13 taken along l~ne
14-14 thereof;
Figure 15 is an illustration of a further mod~flcation
of a method for providiny connections from the output conductor
to the semiconductor chip;
Figure 16 is a perspective view oF a modified form of
semicond~ctor chip in which the output terminals for the semi-
conductor chip are provided on a single face thereof;
Figure 17 is a plan view, partially broken aw~y, of
a method of mounting the semiconductor chip ~f Figure 16 on a
fin and particularly illustrating the connections between the :~
semiconductor chip and the fin and output conductor; and
Figure 18 is a modified form of the invention wherein
the temperature responsive element is attached by thick or thin
filnl techniques.
Figure l9is a perspective view of a preferred form of
fast response fluid temperature sensor incorporating the features
: of the present invention; :-
Figure 20is a cross-sectional view of the improved fluid
temperature sensor of Figurel9 taken along line 2-2 thereof and
particularly illustrating the interconnections between the external ~-
conductors and the semiconductor chip and domed fin; ~;~
Fiyure 21is a cross-sectional view of a mod~fied form
of the improved fluid tenlperature sensor of Figure 19and particu~
larly illustrating a modifica~ion of the manner in which the con-
ductors are led through a molded plast~c memher;
Figure 22is a cross sectional view of a further modifiecl
form of the temperature sensor of the present invention and illus-
trating an alternative method of interconnecting the external con-
ductors to the semiconductor chip and the doomed fin; and
Figure 23is a cross-sectional view of a further modified
form of the temperature sensor illustrating applying the temperature
responsive element with thick film techniques.
D_TAlLED DESCRIPTION ~F THE I VENTI~N
Referring now to the drawings, and part1cular~y Figure l
thereof, there is illustrated a side view of a preferred form
of temperature sensor 20 incorporating the features of the present
invention. The sensor 20 includes three portions, a c~nnectDr ; .
22, the sensor assembly 24 and a pair of interconnecting wires 26 -~
which provlde a connection between the sensor ~4 and the connector `
22. The connector 22 is of the tYpe typically utili~ed in the
automotive industry which includes a housing 28, within which are
formed the plug and socket members utilized to mate with the
corresponding socket and plug members, respectively, in the wiring
harness of the automobile. Suitable interlocking means 30 is
provided to lock the houslna 28 to the corresponding member in
the wiring harness to preclude the two members from being uninten-
tionally disassembled.
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The temperature sensor assembly includes a brass or
other suitable metal f~ttin~ 34 which is adapted to be threaded
into an aperture in the intake manifold of an automobile and
suitably tightened by means of a hexagonal head port~on 36 as
is common in the automotive art~ The temperature sensor
assembly 24 further includes a molded element 38 which ~s
adapted to mount a fin 40 at one end thereof and r~gidly fix
the fin 40 relative to the brass f~tting 34 as we will fully
explain hereinafter. The conductors 26 are molded within the
interior of the plast~c element 3B and, as will be seen herein-
after, the conductors are led up through the center of a pair
of mounting arms 42, 44. The entire assembly including arms 42,
44 and the fin 40 are protected by a wire cage 46 which lnclude
a pair of formed domed wires which are welded at their apex and
the opposite ends thereof are inserted 1nto apertures fcrlned in
the brass fitting 34 and soldered into place. ~hus, the tempera-
ture sensing fin 40, and the semiconductor chip to be described
hereinafter, are protected from foreign elements which may be
injurious to the fin and semiconductor chip shuuld these latter
elements be struck by the foreign elements.
Referring now to Figure 2, wh~ch is a top view of the
temperature sensor assembly 24 of Figure 1, there is illustrated
the particular referred method of mounting the semiconductor chip
on the fin 40 and also the method in which the connect~ons are
made to the conductors 26 froln the fin 40 and a semiconductor
chip4~. 5pecifically, the fin 40 has mounted thereon a nonconductin~
ceramic chip S0 by any suitable method described above, for example
by conductive adhesive, etc. As is seen from Fi~ure 2, the chip
50 is mounted a sli~ht distance away from the mountinq arm 44 to
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permit a conductor 52 cenkered in the mountlng arm 44 to be 'led
up through an aperture formed in the fin 40. The conductor 52 is
then lapped over the top of the fin 40 and attached to the non-
conducting chip 50 as will be more fully explained in coniunction
with the description of Figure 4 a conductor 539 in the form of
a gold wire~ connects the conductor 52 w~th the semiconductor chip
48. Similarly, a conductor 54 which i5 molded into the center
of mounting arm 42 is led up through a second aperture for~ed ~n the
fin 40 and folded over into engagement with the top surface of the
fin 40. The conductor 54 is then suitably attached to fin 40 by
soldering or conductive adhesives.
Flgure 3 illustrates various features of the assembly
nnt illustrated in great detall in Figur~s 1 and 2. For example,
the conductors 26 are molded within the member 38 and suitable
connectors 58, 60 are provided to connect the interconductors
of conductors 26 to the conductors 52, 54. As is seen from Figure
3, the conductors 54 are molded within the mountlng arms 44, 42
respectively and folded over at the tops thereof to form the ,
connections described in con,iunction with Figure 2, The material
forming support elements 42, 44 is of the thermal plastic type
whereby heat is applied to the upper ends of the members 42, 44
and the upper ends are melted over to form a firm at~achment to
the fin 40. As is seen from the left end of the drawing, the
bottom of brass fastener 24 is swaged over at 62 to firmly hold the
molded member 38 within the brass element 36.
Referring to Figure 4, there is illustrated one me$had
of interconnecting the conductor 52 with the semiconductor chip
48. Also illustrated is the heated portion of the upper end of
mounting arm 44 whicn is melted to form the attachment between arm
44 and the ~in 40.
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As is seen froln Figure 4/ the conductor 52 ls led through
an aperture 64 formed in the fin 40 and fo'lded over to f'orm a loop
and a flat portion 66, flat portion being cont~guous ~ith the
upper surface of the chip 60. The portion 66 is then s~ita~ly
attached to the nonconducting chip 50 by any suitable method, as for
example, by using a conductive adhesive forming a mechanical bond
and electrical contact between conductor 66 and chip 50. As will be
seen from the description of Figures 12 to 17, other methods of
attaching the conductors may be utilized or keeping within the
spirit of the invention.
Referring now to Figure 5, there is illustrated a
modified form of the air temperature sensor of the Present invention
which includes substantially the same base element described above
bearing reference numerals 34 and 36 and the same protective cage
wires 46. The modified form as best illustrated ~n Figure 6,' :',
includes a plastic element 70, into which is molded into the conductors
26, the connectc~rs 58, 60 and a pair of conductors 72, 7~. The
conductors 74 is led up through a mounting arm 76 integrally for~ed
as a part of the plastic member 70 and folded over for attachment
to a fin element 78 as will be more fully described in conjunction
with the descriptlon of Figure 7. : ,;
As is seen from Figure 6, the fin 78 is formed with a
dished portion 80 into which is placed a semiconductor chip 82.
lhe semiconductor chip 82 is suitably electrically ccn~ected to,
the conductor 72 by any suitable method as for example that describing
in conjunction with Figure 4 and to be described in conjunction with
Figures 12-15. The dished portion 80 of the fin 78 pro~ides -~'
protection for the chip 82 and enhances the uniform heating of the
chip 82 by the fin member 78.
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r~ f
Referring to Figure 7, it is seen that an aperture
86 is formed in the fin 78, ~hrQugh which is passed a thin upper
portion of the mountin~ arm 76 and the conductor 74. The f1n 76
is heated ~nd melted to form a head ~o securely fasten the ~in 78
to the mounting arm 76. The conductor 74 i~s fDlded oVcr to be
placed in close contact with tha fin 78 and is considerably
attached thereto, for example by soldering or through the use of
adhesives.
Referring now to Figure 8, there is illustrated another
modified form of the assembly of the present invention. Partlcu- :
larly, a base element 86 is provlded which maybe similar to that
described in conjunetion with the description of base element 24.
~lithin the base element is mounted a plastlc support member 8~
which is molded with a base member 90 and a plurality of pairs of
arms 92 including an outer arm 94 and an inner arm 96. As is best
seen in Figure 8, the pairs of support arms 94, 96 are adapted to
rigidly support a generally square fin ele~ent 981 there bein~
four pairs of arms 92, 10~, 102 and 10~.
As is best seen in Fiyures 9 and 10, there is molded
?0 between the inner and outer arms of each pair of arms 92, 102 a
generally U-shaped conducti~e element 106, the conductive element
being formed with a cross rnember 108 and a pair of arms 110, 112.
It will be noted from Figure 9 that the arms llQ, 112 are
generally tapered from the cross member 1~8 to the ~uter end of
the arms 110, 112. It is to be noted that the U-shaped member 106
is only provided between pairs of support arms 92 and 102. Prior
to attaching the disc 98, an aperture 114 is drilled into the
assembly to separate the arm or the conductive member 112 from the
conductive member llO for purpose to be seen from a further
3U explanation of the assembly.
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The molded base member 90 h~s embedded therein a
pair of conductors 120, 122 whlch are electr~cally connected
to the conductive arms 110. 112 respectively by any suitable
means, as for example by solderin~. After assembly of the
disc 98 into place, the ends 124, 126 are heated and folded
o~er to form a rigid attachment of the disc 98 between ~he arms
94, g63 ~he pair of arms 102 is illustrated ln Figure 9, and
also between the pairs of arms 100 and pairs of arms lD4 as seen
in Figure 8. As best seen in Figures 8 and 9J the disc 98 is
provided with a centrally located semiconductor chip 130 mounted ;
on the bottom thereof, with a suitable conductor 132 interconnect- ~ r
ing the semiconductor chip 130 with the cond~ctive element 112.
This connection to the semiconductor chip 130 could be by any
suitable means as for example that illustrated in Figure 4, 12,
13, 14, and 15. 0-F course, suitable insulating material must be
provided between the conductor 132 and the disc 98 to ensure that i ~;
the conductor 132 is insulated from the disc 98. The disc 98 is 1:
caused to overlap the upper end of the conductive arm 110 to 1~
ensure an electrical connection to the conductlve arm 110. Thus, ¦~ ;
the electrical circuit illustrated in Figure ~ is from conductor
120, through conductor 110. through disc 98, chip 130, conduct;or
132, conductor 112, to conductor 122.
Figure 10 illustrates a method of connecting the disc 98
to the conductive member 110 whereby the conductive member 110 is
provided with a 90-degree bend at the end thereof to be placed in
electrical contact with the disc 98. As described above, the
upper end of arm 94 is heated and folded over at end 136 to ensure
a tight connection between the conductive member 110 and the disc I ~
98. i :
Referrin~ now to Figure 11, it is Illustrated a
further modification of the fast response ~r temperatur~
sensor of the present in~ention. ln this modlfied verslon,
a pair of fins 140, 142 are provided, the fins 140, 142 being
generally dished shaped with the apex of each dish faclng the
other apex of the other dish. Sandwiched between the two fins
140, 142 is a semiconductor chip 144 similar to that described I ;
in coniunction with the prevlous flgures. As ~as ~he case
previously, the discs 140, 142 are suitAbly fastened to a
thermal plastic member 146, the thermal plastlc member 146 having
a pair of arms 14~, 150 into which are molded a pa~r of con- ',
ductors 152, 154. As is seen from Figure 11~ the conductor 152
is folded over and suitably soldered to the upper face of fin
142 and conductor 154 exits from the support arm 150 short of the
end thereof and is directed toward the f;n 140 and suitably
soldered thereto. The upper ends of arms 148, 160 are heated
and folded over to provide a rigid attachment for the upper fin
142. While only two arms 1489 150 have been shown, it is to be
understood that molded Plement 146 maybe provlded with four arms
of an identical configuration two arms 148, 150 with the exception
that no conductors will be molded wlthin two of the arms. As was
described in the earlv part of the specification, the confinuration
of Fi~ure 11 provides a slrnple method of electrically connectiny f~ns
1-~0, 142 to the semiconductor chip 144. Also, the confi~uration of
figure 11 does not require the delicate attachment of a conductive
lead to the semiconductor chip as was prevlously described.
Fiyures 12-15 illustrate various other methods of
attdching leads to the serniconductor chip, particularly Figure 12
illustrates the attachment of a fine gold ~ire 160 from a
1,
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conductor 162 molded in a support member 164. the wire being
attached at the other end thereof to a semiconductor chip 166,
The chip 166 is attached ~o a fin member 168 as was described
above. The electrical connection between the fin 168 and a
second conductor 170 ls pro~lded by folding over the end of
conductor 170 and positioning it in face-to-face relation with
the fin 168.
Figure 13 is a similar conf~guration to that described
in conjunction wlth Fi9ure 12 with respect to the mountin~ of the
fin 168 and its interconnection with the conductor 170. However,
a conductor 172 is provided which is molded into the other arm of
support element l64 and folded over at the end thereof to prov~de
an open face for electrical attachment to another conductor. Again,
the chip 166 is provided hut is connected to the conductor 172 .
through a conductor 176. ~he conductor 176 is insulated from the .
fin 168 by means of insulatin~ material 178 sandwlched between the ~ ;
fin 168 and the conductor 176. A bridge is provided between the
conductor 176 and the chip 166 by means of a flap conductor 180 a~
is best illustrated in Figure 14.
Figure 15 illustrates a rather slmple connection between
a chip 182 and a conductor 184. Taking for example an attachment .
to the disc 168, a suitable layer of insulatin~ material 186 is
provided and the conductor 184 is attached to the insulating
material lB6. The conductor 186 could be the conductor illustrated
as conductor 172 in Fi~ure 13. The insulating ma~erial 186 could
be built up tQ the level of the lower face of chip 132 and the
conductor 184 would merely pass across the insulatin~ material 186
and the chip 182 in a straight line rather than the loop illustrated
in Figure 15.
1,
--19--
Figure 16 and 1~ illustrate a modifled form of semi-
conductor chip wherein the chip is provlded with both output
terminals on a single -Face thereof. For exanlple, a chip 188 may
have a pair of terminal pro~jections 190, 192 formed thereon,
which projections are utili~ed -to form the terminals for con-
nection to the disc and external conductor associated with the
chip. Figure 17 ill IIS trates this particular connection wherein
a disc 194 is provided with a strip of insulating material 196
and a conductor 198. lhe chip 1~8 is then positioned as shown
wherein the projection 192 is an electrical contact with the fin
194 and the projection 190 is in contact with the strip conductor
198. The strip conductor can then be connecte~ to the chip
associated support arms illustrated in Figures 3, 9 or 11.
~igure 18 illustra~es the invention as applied by thick
film techniques. While thick film application is described, it is
to be understood that thin filnl techniques apply equally as well.
Referring to the drawin~, the fin 40 forms the substrate on ~hich
the various layers are deposited by the screening process. In
carrying out the process, an insulating strip 200 is deposited on the
fin 40 with an aperture 202 formed in the strip 200 hy either blocking
the area of the aperture 202 with an emulsion or by etching the
ared of the aperture from the strip 200. A semiconductor portion
204 is then deposited in the aperture 202 in contact with the fin 40.
Finall~y a strip conductor 2~6 is deposited on the portion 204
and on strip 200, and within the confines thereof, to form the
conductive strip corresponding to strip 19~ in Figure 17, or conductor
53 in Figure 2. In the thin film counterpart~ the various layers are
sputtered or evaporated with the necessary masking or etching
to fornl the desired shapes.
-20-
$ ~
A preferred form of the above described temperature sensor
included a brass disc having a thickness of between 3 and 4 mils and
a diameter of approximately 7/16 inch, and the response time of the
sensor is approximately one second for one hundred declrees change
in temp~rature. The above dimensions provide a f'in which is
sufficiently stiff while maintaining the high surface area to mass
ratio required to give the desired fast response time.
Referring to Figurel9, there is illustrated a fluid
temperature sensor 208 which is extremely fa~t and highly stable in
its response which includes a bdse member 210,a sensing assembly
212,a protective cage 214for the sensing assembly 212,and a pair
of external conductors 216~lhictl are utilized to inlerconnect the
dome and semiconductor chip i;o external circuitry. The base element
210 includes a threaded portion218 which Is adapted to be threaded,
for examp1e, into the air intake of an ~nternal combustion engine
or other device through which fl~id is flowiny and the temperature
of that fluid is to be sensed. As is common in devices of this type,
the bas~ member210incllldes a h~xa(1onal portion220which is u~ilized
to tighten the sensor into position.
The sensing assembly 212includes a domed fill224which~
as can be seen from Figure 20,is utili~ed to conduct heat to and
away from a semiconductor chip while protecting the chip, and
associated connecting conductors, from contaminants and other
foreign material The dome memDer 224,which is extremely thin to
reduce its mdss-to-area ratio as e~plained in the aforementioned
applications, is protected by means of the cage214which includes
-21-
a pair of U-shaped wires 226,228positioned at 90, one relative
to the other, and inserted into apertures formed in the ~ase
member 210and suitably attached therein~
Referring now to Figure 20,there is also illustrated
a cross-section of the air temperature sensor of Figure 19 to
illustrate the interior portion of the temperature sensing el~nent
212. As is seen from this drawing, the external conductor 216,
which include a pair of conductive members230,232 are molded in
a plastic member234, which plastic member is rigldly seated within
the base member 210. In order to ensure that the molded member 234
is rigidly positioned within the base member210, a lip 236 is
swaged over the bottom of the molded element234 to securely position
the molded member234 within the cavity formed by th~ base member 210.
The conductor 230is, in the embodiment shown in Figure 20,
turned at 90 at portion 238and mechanically contacts the ;nner
surface of the domed member 224to effect an electrical connection
between the conductor230and the fin 224. On the other hand, conduc-
tor 232is led straight through the molded member234 to a position
above the top of the molded member 234but within the confines of
the fin224. A connection ls made between the top of conductor 232
and a semiconductor chip240 by means of a fine gold wire242 ha~lng
a diàmeter of approximately .002 ;nches.
Thus~ as is seen from Figure 20,the chip 240, gold wir~
242, andthe interior pnrtion of the domed fin224 are protected
from any contaminants or foreign material which may flow past the
domed fin224. As stated above, the interior of the domed fin 224
may be provided with foamed material to further mechanically
protect the semiconductor chip240 and the gold wire 242.
-22-
Referring now to Figure 21,there is illustrated a
modified form of connections whereby the conductors230, 232 are
embedded in a modif~ed molded plastic member 246. The plastlc
member 246~s modified by providing cutaway portions at surfaces
248an~ 250 to provide access to the top Df conductors 230, 232 which
are now positioned outside of the confines of a domed fin 252.
The connections between the conductor230and the Fln 252
is provided by a gold wire 254having a diameter of approxlmately
.002 inches, the gold wire being suitably fastened to the domed
fin 252. As was the case with ~igure 20,a semiconductor chip 258
is mounted within the fin 252 and at the apex thereof, and the con-
ductor232is interconnected therewith by a second gold wire 260.
The bonding of the semiconductor258 to the domed fin2s2 may be by ;~
any suitable methods, as for example, by gold bonding techniques.
The domed fin 252is press-fitted onto the upper end of the plastic
molded member 246and fixed thereto.
Referring now to Figllre 22,there is illustrated a further
modification of the invention disclo,ure wherein the dorned element
252is again provided with a semiconductor chip 258. However, a
molded member264 is shown as being modified from that previously
described except that the domed fin 252is again press-fitted onto
the plastic molded memben264 and suitably attached thereto. In
the case of Figure 22,the conductor230is provided at its upper
end thereof with a flexible whisker-type lead 266which is in wiping
contact with the domed fin 252thereby providinq electrical connec-
tion thereto. On the other hand, the conductor 232is provided
with a slightly longer flexible whisker-type lead 268which is in
wiping contact with the semiconductor chip 258.
-23-
Figure ~3illustrates the invention as applied by
thick film techniques, although lt is to be understood thin
film techniques apply equally as well. Referring to Figure 23,
fin2s2forms the substrate on which the various layers are
deposited by the screening process. In carrying out the process,
an insulating strip 270j 5 deposited on the fin 252with an
aperture 272formed in the strip270 by either blocking the area
of the aperture 272with an emulsion or by etching the area of
the aperture from the strip. A semiconductor portion274 is then
deposited in the aperture272in contact with the fin252. Finally
a strip conductor276is de,uosited on the semiconductor274and on
strip 270, maintaining the conductor 276, within the confines ~ -
thereof, to form the conductive strip corresponding to the
conductor 242 or 260. III the thin film counterpart, the various
layers are sputtered or evaporated with the masking or etching
desired to form the stIapes needed.
Having described a preferred embodiment of the inven~
- tion and several modi1~ications thereof, it will be understood
that the examples given are employed in a descriptive sense only ;~
and not for purposes of limitation. Other embodiment and vari-
ations will be obvious to those skilled in the art and be Inade
without deploying from the spirit and scope of my invention which
is li~ited only by the appended claims.
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