A light-weight, inexpensively fabricated, hermetically sealable, repairable package for small electronic or electromechanical units, having multiple connections, is described. A molded ring frame of polyamide-imide plastic (Torlon) is attached along one edge to a base plate formed of a highly heat conducting material, such as aluminum or copper. Bores are placed through a base plate within the area of the edge surface of ring frame which result in an attachment of the ring frame to the base plate during molding. Electrical leads are molded into the ring frame. The leads are L-shaped gold-plated copper wires imbedded within widened portions of the side wall of the ring frame. Within the plastic ring frame wall the leads are bent (typically, though not necessarily at 90 deg) so that they project into the interior volume of the ring frame for connection to the solid state devices

Gray, Ormal E.

Miller, Wilson N.

English

NASA Technical Reports Server

United States Patent [191 [11] Patent Number: 4,750,031 
Miller et al. [45] Date of Patent: Jun. 7, 1988 
[54] HERMETICALLY SEALABLE PACKAGE 
FOR HYBRJD SOLID-STATE ELECTRONIC 
DEVICES AND THE LIKE 
[75] Inventors: Wilson N. Miller, Anaheim; O d  E.
Gray, Placentia, both of Calif. 
[73] Assignee: The United States of America as 
represented by the United States 
National Aeronautics and Space 
Administration, Washington, D.C. 
[21] Appl. No.: 392,093 
[22] Filed: J~n.25~1982 
[51] Int. CI.4 ........... HOlL 29/44; HOlL 23/30; 
HOlL 23/06; HOlL 23/10 
[52] U.S. c1. ........................................ 357/81; 357/72; 
357/74; 174/52 S; 174/52 P E  174/52 R, 
525/425 
[58] Field of Search ............................. 357/81, 72, 74; 
174/52 S, 52 PE, 52 R; 525/425 
~561 References Cited 
US. PATENT DOCUMENTS 
3,155,766 11/1964 Eichert et al. ............ 357/72 
3,236,936 2/1966 Robinson .............................. 357/72 
3,390,226 6/1968 Beyerlein .............................. 357/72 
3,404.213 10/1968 Brookover et al. .................. 357/74 
3,430,835 3/1969 Grable et al. ............. 357/74 
3,693,239 9/1972 Dix ........................................ 357/74 
3,767,839 10/1973 Beal ....................................... 357/74 
3,789,341 1/1974 Dalmasso .............................. 357/74 
3,829,598 SA974 Darnell ................................. 357/81 
3,906,144 9/1975 Wiley .................................. 174/525 
4,012,579 3/1977 Fox et al. ............ 174/52 PE 
4,126,758 11/1978 Knunme ............................... 357/74 
4,172,261 10/1979 Tsuzuki et al. ....................... 357/81 
4,303,934 12/1981 Sfitt ....................................... 357/75 
4,330,683 5/1982 Parker ................................... 357/74 
4,331,831 5/1982 Ingram et al. ........................ 357/81 
4,340,697 7/1982 Aya et al. ............................ 525/425 
FOREIGN PATENT DOCUMENTS 
0037301 10/1981 European Pat. Off. .............. 357/74 
976278 11/1964 United Kingdom .................. 357/74 
2057757 4/1981 United Kingdom .................. 357/74 
Primary Examiner-Andrew J. James 
Assfitant Examiner-Jerome Jackson 
Attorney, Agent, or Finn-Russell E. Sch loa  John R. 
Manning; Edward K. Fein 
[571 ABSTRACT 
A small component package employing a ring frame 11 
of a mouldable polyamide-imide thermoplastic directly 
moulded onto a heat conducting base plate 10 with 
integral moulded anchoring pins of the thermoplastic 
material engaging corresponding bores 21 and 22 
through the base plate. The other edge of the ring frame 
11 is metalized as is the interface area 13 with a cover 
plate 12 of the same thermoplastic material for a 
soldered seal. Multiple solid electrical leads 17, 18, 19, 
20 are moulded into the ring frame 11 during the base 
plate-to-ring from moulding operation to provide an 
inexpensive, sealed package which is also light in 
weight. Threaded inserts 14 facilitate a firm connection 
to an external heat sink surface along surface loa of base 
plate 10. 
6 claims, 2 Drawing Sheets 
https://ntrs.nasa.gov/search.jsp?R=19880014557 2020-03-23T19:51:08+00:00Z
US. Patent JU. T, 198s Sheet 1 of 2 4,750,031 
FIG. I 
US. Patent J U ~ .  7,1988 Sheet 2 of 2 4,750,031 
4,750,03 1 
1 2 
tion are required in this package and overall weight is 
obviously relatively large. 
U.S. Pat. No. 3,433,885 is another “all metal” enclo- 
sure for a single power semiconductor device. This 
5 enclosure is not adapted for multiple lead circuits such 
as semiconductor hybrids and is relatively heavy. 
Devices of the prior art including those specifically 
mentioned hereabove suffer from the disadvantages of 
high cost of manufacture, relatively large weight fac- 
HERMETICALLY SEALABLE PACKAGE FOR 
HYBRID SOLID-STATE ELECIRONIC DEVICES 
AND THE LIKE 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance Of work under a NASA ‘Ontract and is sub- 
ject to the provisions Of Section 305 Of the National 10 tors and poor adaptability where multiple electrical 
Aeronautics and Space Act Of 19589 connections are required. Wherever glass-to-metal or Law 85-568 
(72 Stat. 435; U.S.C. 2457). ceramic-to-metal seals are used, there is a hazard of 
chipping, fracture, loss of hermetic seal and electrical 
breakdown. Unintended mechanical stress applied to 
through such significantly in- 
creases the hazard of such damage and consequent elec- 
trical brekdown. 
The manner in which the invention deals with the 
disadvantages inherent in the prior art to produce a 
20 novel structure having particular advantages will be 
understood as this description proceeds. 
TECHNICAL FIELD 
device Packages and more specifically to hermetically 
sealed packages for hybrid solid-state devices, small 
electromechanical apparatus, and the like. 
BACKGROUNDART 
In the electronic arts, encapsulation of electrome- 
chanid or hybrid semiconductor arrangements or the 
like is required in order to stabilize many of the ambient 
conditions to which these elements are subjected and to The invention comprises a light-weight, inexpen- 
protect them from extremes of other conditions. This 25 sively fabricated, hermetically sealable, repairable pack- 
encapsulation or packaging has been variously accom- age for electronic or electromechanical devices of small 
plished. In particular, where hermetic sealing is re- size, especially for multi-connection devices such as 
quired, metallic enclosures with glass-to-metal electri- solid-state hybrids. 
cal lead feed through has been the standard approach. A moulded ring frame of polyamide-imide plastic 
m e n  the package is small and appreciable voltage 30 material is adhered along one edge to a base plate. The 
and power levels are extant, the conventional glass-to- base plate &-ofhighly heat conducting material, such as 
metal electrical feed through arrangements are difficult ahmnhum or copper, typically. Bores through the base 
to manufacture and relatively expensive. Moreover, Plate Within the area of edge surface ofthe ring frame in 
such seals are to and fail- contact with the base plate afford attachment of the ring 
ure due to incidental mechanical stresses. 35 frame to the base plate during the moulding operation. 
prior art packages of the type and size The ring frame plastic material flows into these bores in 
in the invention have been made from such materials as the sing1e moulding step 
The electrical leads are contemporaneously moulded Kovar, steel, aluminum, copper, molybdenum and ce- 
ramic materials, all of which are relatively heavy and into the ring frame. These leads are “L-shaped” gold- 40 plated copper wires imbedded in the ring frame walls as costly. they extend in the normal direction with respect to the 
termined point or points within the plastic ring frame in the patent literature, as follows: 
wall the leads are bent (typically, although not necessar- closure with the aforementioned glass-to-metal seals for 45 ily at so that they project into the interior volume 
of the ring frame for connection to the solid-state device the electrical feed through leads. 
“snap-in“ header which is not hermetically sealable and generating heat and can be in thermal 
does not provide a heat sink feature. contact with the base plate surface within the enclosure. 
Of a metallic 50 The outside surface of the base plate is suitable for con- 
enclosure for a solid-state hybrid. Glass-to-metal seals ventional to a massive heat G ~ ~ -  
are shown to provide the large number Of erally the base plate would be flat and attached to the 
electrical leads required for connections to the hybrid external heat sink with a heat conductive compound 
sealed therein. material between the base plate and external heat sink. 
The hermetic enclosure afforded is completed by a 
plate, preferably of the same plastic material as the ring 
ring frame so that the cover plate can be conventionally 
U S  pat. NO. 2,932,684 appears to be a nomepairable 60 soldered in place and removed and subsequently resol- 
dered, if necessary. The cover can be attached other- 
wise, of course, with epoxy adhesives, for example. 
The details of a typical and preferred embodiment of 
the invention will be more fully described hereinafter. 
BRIEF DESCRIPT1oN OF THE 
The details of the invention will be described in con- 
The invention relates generally to sealable electronic 15 the leads 
DISCLOSURE OF THE INVENTION 
The known pertinent prior art is described base plate from their external projections. At a prede- 
u’s‘ pat’ No. 3’621’1 l2 proposes a ferrous metal en- 
u*s* pat’ No* 3,575,546 shows a plastic body with or devices therein. Those devices may be of the type 
pat. No* 375489076 is further 
US. Pat. No. 3,538,597 deals with a cover plate for a 55 
‘‘flat pack” Containing lIliCrOCirCUitS O r  the like. The 
metallic housing (although the insulation Of electrical 
cover plate over the other ring frame edge. A cover 
frame, may be metallized along with the edge of the 
KOVar Cover Plate (lid) is soldered Onto an apparently 
leads passing therethrough is not shown). 
encapsulation device of typical early form. Many in&- 
vidual parts are included in a relatively massive, single 
power transistor package. 
U.S. Pat. No. 3,419,763 contemplates the paralleling 
of a plurality of individual solid-state devices within a 65 
sealed housing structure with heat sinking features. The 
familiar glass-to-metal electrical lead seals through its 
base and metallized ceramic seals for top cover penetra- nection with accompanying drawings in which 
4,750,03 f 
3 4 
FIG. 1 is a top view of the ring-frame and base assem- 
bly of the invention combination before installation of 
the cover plate; 
FIG. 2 is a side view of the package of FIG. 1 with 
the cover plate in place, the view being a partial section 5 
taken as indicated on FIG. 1; 
FIG. 3 is an end view of the package of FIG. 1 and 
FIG. 2 with cover plate in place. 
in connection with hybrid circuits operating at voltages 
up to lo00 volts dc. The addition of the glass fiber im- 
proves the ring frame coefficient of expansion match, 
vis-a-vis, a copper base plate at 10. 
The metallizing of the edge surface of ring frame 11 
at interface 13 and the congruent portion of Torlon 
cover plate 12 is by plating, sputtering, painting on with 
subsequent bake, or other conventional processes. The 
Torlon material is well adapted to metallizing, and for 
10 hermetic sealing along interface 13, a solder preform 
can be inserted and heat applied by induction heating or INVENTION 
Referring now to FIG. 1 and FIG. 2, the base plate 10 other conventional means. 
is seen to be attached to the ring frame 11 during the The tooling required in the injection moulding pro- 
moulding of the ring frame. In FIG. 2, bores, typically cess, including the holding in place of the electrical 
21 are shown with expanded head potions 22 such that, 15 leads during moulding, can be readily provided within 
during the moulding of 11, “pins” are formed which are the skill of that art. 
integral with the ring frame 11 and act to hold the edge The electrical leads are normally copper, and their 
of the ring frame into tight contact with the base Plate adherence to the Torlon moulding is enhanced by gold 
in a tension grip. The plastic material employed flows plating conventionally applied. 
readily into the bores 21 and head Portio- 22 and 20 Some typical dimensions giving a concept of the 
harden therein as the M Y  of ring frame 11 hardens. physical sues typical of packages according to the in- 
Still further, there is substantial direct adherence of the vention are as follows: 
plastic material to the surface of base plate 10 along the 
interface area between them. 
FIG. 1 in particular, the cover plate 12 shown in FIG. 
2 preferably having am outside perimeter shape the same 
as that of ring frame 11. 
It will be noted that the plural electrical leads of 
which 17, 18, 19 and 20 are typical9 extend and are 30 
imbedded within widened portions 15 and 16 of the ring 
cover plate. At a predetermined point (or points, not 
BEST CARRYING OUT THE 
The shape of the ring frame member can be seen in 25 dimension centimeters 
a 12.19 
b 3.05 
C 0.18 
d 1.02 
e 0.5 1 
f as required 
g 0.23 
h 0.18 
0.51 
k per constraints 
frame side wall, thereby avoiding interference with the 
n e c e s d y  in alignment) the leads are bent inward to 
j 
enter the ‘ulterio; volume within the ring frame 11 as 
enclosed by the base plate 10 and cover plate 12. The 
points at which the leads enter this interior volume may 
be staggered as desired to accommodate the circuitry 
therein. 
It will be realized that the resistance to mechanical 
damage (of the type which is often destructive of glass- 
to-metal seals) afforded by the configuration of leads 
shown is much superior to that afforded in prior art 
arrangements. 
The ends of leads 17, 18, 19 and 20 extending exter- 
nally are visible at 170, 18a. 19a. and 20u in FIG. 3. In 
addition to the moulding of the ring frame 11 to base 
plate 10, the aforementioned leads are moulded in place 
during the same operation. Still further, four threaded 
inserts (typically 14) are moulded into the ring frame 
itself for attachment of the entire assembly by means of 
screws through the external heat sink into these inserts 
from the 1Oa side of 10. Bore 21 provides an overtravel 
space for such screws. 
At this point in the description the preferred material 
for the ring frame 11 and cover plate 12 will be de- 
scribed. That preferred material is a polyamideimide 
thermoplastic generically classed as an amorphous pol- 
ymer. Such a material is available from Amoco Chemi- 
cal Co. under the trademark 6‘Torlon’’, and is ideal for 
injection moulding. It is available in a standard grade 
produce as Torlon 5030 with 30% glass fiber and 1% 
ITFE (polytetrafluorethylene). Whew hardened, Tor- 
lon is very strong, has a dielectric strength on the order 
of 600 volts/mil and a volume resistivity of at least 
1.ZX 1017 ohm-cm, thereby affording the electrical 
properties suitable for relatively high voltage circuits. 
One particularly advantageous use for the invention is 
35 
The constraints affecting dimension k include the 
height of the semiconductor components, the voltage 
requirements and the “reach” capabilities of the hybrid 
bonding equipment. 
40 The particular dimensions accommodate four 
0.635 ~ 0 . 6 3 5  centimeter (0.25 X0.25 inches in the trade) 
semiconductor chips continuously dissipating 40 watts. 
The heat generated is removed by thermal contact of 
these chips with base plate 10 and hence to an outside 
FIG. 3 shows the same structure as FIG. 2, viewed 
from a 90” rotated point (end view). The Torlon cover 
plate 12 is nominally 0.50 cm. in thickness. The ring 
frame wall thickness varies in the embodiment shown, 
50 but can provide proper strength and stability in rela- 
tively thin sections. The Torlon material has a deflec- 
tion (transition) temperature on the order of 270” Cel- 
sius. Moreover, it is resistant to nuclear and ultraviolet 
radiation, is rated 94V-0 (Underwriters Laboratory 
55 rating) for flame retardancy, and is out-gas free after 
curing. Unsealed, it will absorb and release a maximum 
of 0.22% water by weight at 21” Celsius with substan- 
tially no chemical or dimensional changes. 
The Torlon material is an excellent substitute for 
60 metal, providing excellent strength amd other character- 
istics. The overall weight of an assembly according to 
the invention is on the order of half of that of a compa- 
rable package fabricated from lightest structural metals 
and may be even much lighter in comparison to Kovar, 
From the foregoing, it will be evident that the cost of 
manufacture is much less than for conventional prior art 
packages for the purpose. This is achieved in large 
45 heat sink through base plate 10. 
65 ferrous metal or ceramic implementations. 
4,750,03 1 
5 
measure through the moulding process in which the 
ring frame is wedded to the base plate and the electrical 
leads are embedded all in one operation. 
It is again emphasized that the embedded lead config- 
uration is highly resistant to twisting or other mechani- 
cal stresses and also to vibration and thermal shock. 
Those effects are capable of causing failure of the her- 
metic sealing in the prior art. 
In view of its relatively low cost and other advan- 
tages, the invention is applicable to a wide variety of 
uses, such as in aircraft systems, electric automobiles, 
industrial equipment, shipboard electronics, solar cell 
arrays, satellites and other space vehicles. 
Variations within the scope of the invention will 
suggest themselves to those of skill, once the invention 
is understood. Accordingly, it is not intended that the 
invention should be regarded as limited to the specific 
form and materials shown and described. The drawings 
and this description are intended to be typical and illus- 
trative only. 
We claim: 
I. A sealed solid-state electronic hybrid package 
comprising: a base plate for mounting at least one elec- 
tronic component in thermal contact along a first sur- 
face of said base plate, said base plate having a second 
surface adapted to be mounted in thermal contact with 
a surface of an external heat sink, said base plate formed 
of a metal having high heat conductivity; a ring frame 
formed of amorphous polymer polyamide-imide mate- 
rial having approximately 30% glass fiber and 1% 
PTFE moulded into contact with said base plate first 
surface about a first edge surface of said ring frame, said 
ring frame having at least one electrical lead moulded 
through a side thereof, said lead projecting into the 
interior volume of the ring frame for connection to the 
electronic component; and a cover plate fabricated 
from amorphous polymer polyamide-imide material 
5 
10 
15 
20 
25 
30 
35 
40 
6 
having approximately 30% glass fiber and 1% PTFE 
overlying a second edge surface of said ring frame, said 
second ring frame edge surface and the congruent area 
of said cover plate being metallized, said metallized ring 
frame edge and metallized cover plate area being 
soldered together. 
2. The apparatus according to claim 1, in which said 
base plate comprises a plurality of bores therethrough 
within said edge surface of said ring frame, said ring 
frame including pins of said mouldable thermoplastic 
integral with said ring frame extending into said bores as 
a part thereof to secure said ring frame against said base 
plate. 
3. The apparatus according to claim 2 in which at 
least some of said bores include an expanded diameter 
section adjacent to said base plate second surface, said 
pins thereby having a correspondingly enlarged end 
adjacent said base plate second surface for securing said 
ring from against said base plate first surface. 
4. The apparatus according to claim 1 in which said 
electrical leads are L-shaped conductors, a first leg of 
said L-shape extending within the wall thickness of said 
ring frame from external points of connection to a point 
within said ring frame wall at which said leads are bent 
to form the second leg of said L-shape extending into 
the interior volume within said ring frame. 
5. Apparatus according to claim 4 in which the side 
wall of said ring frame has increased thickness extend- 
ing laterally outward beyond said cover plate surround- 
ing said electrical leads whereby said electrical lead first 
legs pass laterally outward with respect to said cover 
plate. 
6. Apparatus according to claim 1 in which said met- 
allized portions of said ring frame and cover plate are 
areas of plated-on copper. * * * * *  
45 
50 
55 
60 
65 


Hermetically sealable package for hybrid solid-state electronic devices and the like

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