Package for housing semiconductor elements

A package for housing semiconductor elements including an insulating base which consists of electrical insulation material, and has a mounting portion that mounts semiconductor elements on the upper surface as well as a plurality of depressions on either of the upper surface and the lower surface thereof, a plurality of metallized wiring layers led away from the periphery of the mounting portion and extending to one end surface of the depressions, a plurality of connection pads for electrically connecting the metallized wiring layers formed on the end surface of the depressions of the insulating base and terminals which are soldered to the connection pads, wherein the terminals are accurately attached by solder to designated positions on the connection pads and securely and strongly joined to designated wire conductors of external electronic circuit boards to achieve reliable electrical connections of semiconductor integrated circuit elements housed inside the package to external electronic circuit boards.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention, relates to a package for housing semiconductor 
elements for the purpose of housing semiconductor integrated circuit 
elements and the like. 
More specifically, the invention relates to a package for housing 
semiconductor elements that can accurately electrically connect each 
electrode of semiconductor integrated circuit elements to external 
electronic circuits. 
2. Related Art 
In the past, packages for housing semiconductor elements, in particular, 
semiconductor integrated circuit elements such as LSI (large-scale 
integrated circuits), were generally made of electrical insulating 
materials like alumina ceramic and comprised an insulating base having a 
depression at nearly the center section on top of the packages for housing 
the semiconductor integrated circuit elements, a plurality of metallized 
wiring layers formed of high melting point metallic powders such as 
tungsten or molybdenum led away from the periphery of the depression of 
the insulating base and extending to the lower surface thereof, a 
plurality of connection pads formed on the lower surface of the insulating 
base which are electrically connected to the metallized wiring layer, ball 
terminals consisting of solder (brazing filler) hard-soldered to the 
connection pads, and a lid. 
Such packages for housing semiconductor elements become a semiconductor 
device that can be fabricated as a product by attaching the semiconductor 
integrated circuit elements to the bottom surface of the depression of the 
insulating base using an adhesive consisting of materials such as glass or 
resin; electrically connecting each electrode of the semiconductor 
integrated circuit elements to the metallized wiring layer by means of 
bonding wires while joining a lid to the upper surface of the insulating 
base using a sealant such as glass or resin; and hermetically sealing the 
semiconductor integrated circuit elements inside a container consisting of 
the insulating base and the lid. 
Such semiconductor devices are operably mounted on an external electronic 
circuit board by installing ball terminals, which are formed of solder 
hard-soldered to the connection pads on the lower surface of the 
insulating base, on the wire conductor of the external electronic circuit 
board to make contact each other; thereafter fusing the ball terminals at 
about 150.degree. C. to 250.degree. C.; and thereby joining the ball 
terminals to the wire conductor. Simultaneously, each electrode of the 
semiconductor integrated circuit elements housed inside the package for 
housing semiconductor elements is electrically connected to the external 
electronic circuit by means of a metallized wiring layer and the ball 
terminals. 
However, in these packages for housing semiconductor elements in the prior 
art, the coefficient of thermal expansion of the insulating base made of 
alumina ceramic was on the order of 6.5.times.10.sup.-6 /.degree.C., 
whereas an external electronic circuit board, which is generally made of 
glass epoxy, has a coefficient of thermal expansion of from 
2.times.10.sup.-5 /.degree.C. to 4.times.10.sup.-5 /.degree.C. Because 
there was a large difference between the two coefficients, when the 
semiconductor integrated circuit elements were housed inside the package 
for housing semiconductor elements followed by being operably mounted on 
the external electronic circuit board and, heat generated while the 
semiconductor integrated circuit elements are operated was repeatedly 
applied to both the insulating base and the external electronic circuit 
board, a large thermal stress occurred between the insulating base of the 
package and the external electronic circuit board due to the difference of 
both coefficients of thermal expansion. This stress acted on the 
peripheral portion of the connection pads on the lower surface of the 
insulating base to separate the connection pads from the insulating base. 
A defect that occurred as a result of this was that, over a long period of 
time, each electrode of the semiconductor integrated circuit elements 
housed inside the package for housing semiconductor elements could not be 
electrically connected to the designated external electronic circuits. 
As a further example of the package for housing semiconductor elements in 
the prior art, packages using ball terminals hard-soldered to the 
connection pads by means of a brazing filler have been known to be used in 
place of ball terminals which consist of solder brazer mounted to the 
connection pads. 
Such semiconductor devices are operably mounted on the external electronic 
circuit board by installing ball terminals, which are hard-soldered to 
connection pads on the lower surface of the insulating base, on the wire 
conductor of the external electronic circuit board to make contact each 
other and by joining the both by solder. Simultaneously, each electrode of 
the semiconductor integrated circuit elements housed inside the package 
for housing semiconductor elements is electrically connected to the 
external electronic circuit by means of the metallized wiring layer and 
ball terminals. 
However, these packages for housing semiconductor elements in the prior art 
had a defect in that the semiconductor elements housed inside could not 
accurately and reliably provide an electrical connection to the external 
electronic circuit because of the fact that the connection pads provided 
on the lower surface of the insulating base were flat and the terminals 
joined to the wire conductor of the external electronic circuit board were 
balllike resulting in variations in the hard solder positions due to 
movement of the ball terminals which occurred easily with these variations 
making it impossible to install the terminals while making contact and 
thus joining the wire conductor of the external electronic circuit board. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a package for housing 
semiconductor elements in which each electrode of the semiconductor 
integrated circuit elements housed inside can be accurately, electrically 
connected to designated external electronic circuits over long periods of 
time. 
It is another object of the invention to provide a package for housing 
semiconductor elements in which ball terminals can be accurately 
hard-soldered at designated positions on connection pads formed on the 
lower or upper surface of an insulating base to securely and strongly join 
the ball terminals to designated wire conductors of a external electronic 
circuit board and thereby to allow for the semiconductor integrated 
circuit elements housed inside to be accurately electrically connected to 
the external electronic circuits. 
In one aspect of the invention, there is provided a package for housing 
semiconductor elements, the package comprising an insulating base, which 
consists of electrical insulation material, the insulating base having on 
the upper surface thereof a mounting portion that mounts the semiconductor 
elements as well as a plurality of depressions on either of the upper 
surface and the lower surface thereof; a plurality of metallized wiring 
layers led away from the periphery of the mounting portion and extending 
to one end surface of the depressions; a plurality of connection pads for 
electrically connecting the metallized wiring layers, formed on the end 
surface of the depressions of the insulating base; and terminals which are 
soldered to the connection pads, each terminal forming integrally with the 
soldered portion, a ball protrusion on the surface of the insulating base, 
wherein the following equations must be satisfied with respect to 
D.sub.1a, D.sub.2 and d where D.sub.1a represents the diameter of the ball 
protrusion, D.sub.2 represents the diameter of the opening of the 
depression, and d represents the depth of the depression: 
D.sub.2 &lt;D.sub.1a 
0.2 (mm).ltoreq.D.sub.2 .ltoreq.1.0 (mm) 
d.gtoreq.0.05 (mm) 
0.08.ltoreq.d/D.sub.2 .ltoreq.0.85 
Preferably, the terminal comprises a low melting point lead-tin solder with 
a lead-to-tin weight ratio of about 6:4. 
In another aspect of the invention, there is provided a package for housing 
semiconductor elements, the package comprising an insulating base, which 
consists of electrical insulation material, the insulating base having on 
the upper surface thereof a mounting portion that mounts the semiconductor 
elements as well as a plurality of depressions on either of the upper 
surface and the lower surface thereof; a plurality of metallized wiring 
layers led away from the periphery of the mounting portion and extending 
to one end surface of the depressions; a plurality of connection pads for 
electrically connecting the metallized wiring layers, formed on the end 
surface of the depressions of the insulating base; and ball terminals 
which are soldered to the connection pads, wherein the following equations 
must be satisfied with respect to D.sub.1b, D.sub.2 and d where D.sub.1b 
represents the diameter of the ball terminal, D.sub.2 represents the 
diameter of the opening of the depression, and d represents the depth of 
the depression: 
D.sub.2 &lt;D.sub.1b 
0.2 (mm).ltoreq.D.sub.2 .ltoreq.1.0 (mm) 
D.sub.1b -(D.sub.1b.sup.2 -D.sub.2.sup.2).sup.1/2.ltoreq. 2 d 
Preferably, the ball terminal comprises a high melting point lead-tin 
solder with a lead-to-tin weight ratio of about 9:1. More preferably, the 
ball terminal is soldered to the connection pads using a low melting point 
lead-tin solder with a lead-to-tin weight ratio of about 6:4. 
The above objects, as well as further objects, features and advantages of 
the present invention, will be more fully understood by reference to the 
following detailed description and the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
This invention will be described in detail by way of example with reference 
to the accompanying drawings. FIGS. 1 and 2 show a preferred embodiment of 
the package for housing semiconductor elements according to this 
invention. In FIG. 1 is there shown an insulating base 1 and a lid 2. This 
insulating base 1 and lid 2 comprise a package 4 that houses a 
semiconductor integrated circuit element 3. 
At the center section of the upper surface of the insulating base 1, a 
hollow part 1a is provided in order to house the semiconductor integrated 
circuit element 3, and the semiconductor integrated circuit element 3 is 
attached to the bottom surface of the hollow part 1a by an adhesive such 
as glass or resin. 
The insulating base 1 is made of electrical insulation material including 
aluminum oxide sintered body, mullite sintered body, silicon carbide 
sintered body, aluminum nitride sintered body, and glass ceramic sintered 
body. For example, when the insulating base is made of aluminum oxide 
sintered body, the insulating base is produced by mixing appropriate 
organic binder, plasticizer and solvent with the raw material powders of 
aluminum oxide, silicon oxide, magnesium oxide and calcium oxide to 
prepare a slurry substance, forming a green sheet utilizing the doctor 
blade method or calendar roll method, applying an appropriate punch 
process to the green sheet, laminating a plurality of the green sheets and 
firing the sheets at a temperature of approximately 1600.degree. C. 
Furthermore, on the insulating base 1 a plurality of metallized wiring 
layers 5 are attachably formed from the periphery of the hollow part 1a 
where the semiconductor integrated circuit element 3 is mounted and 
housed, and extends to the lower surface of the insulating base. 
As shown in FIG. 2, a depression 1b is further provided on the lower 
surface of the insulating body 1 and on the bottom surface of this 
depression 1b, a connection pad 5a is attachably formed to be electrically 
connected to the metallized wiring layer 5. 
The metallized wiring layer 5 and connection pad 5a are formed of high 
melting point metallic powders such as tungsten, molybdenum or manganese. 
The metallized wiring layer 5 and connection pad 5a are then attachably 
formed in a designated pattern at a designated position on the insulating 
base 1 by applying a metal paste, obtained by mixing appropriate organic 
binder, plasticizer and solvent with a high melting point metallic powder 
such as tungsten, in a designated pattern to a green sheet that will form 
the insulating base 1 in accordance with the screen printing method which 
is well-known in the prior art. 
The metallized wiring layer 5 electrically connects each electrode of the 
semiconductor integrated circuit element 3 to a terminal 7 which is 
soldered to the connection pad 5a (explained later). Each electrode of the 
semiconductor integrated circuit element 3 is electrically connected at a 
region positioned at the periphery of the hollow part 1a of the insulating 
base 1 by means of a bonding wire 6. 
Moreover, the connection pad 5a electrically connecting the metallized 
wiring layer 5 serves as a substrate metal layer when the terminal 7 is 
attached to the insulating base 1. The terminal 7 comprising a low melting 
point lead-tin solder with a lead-to-tin weight ratio of about 6:4 is 
soldered to the surface of the connection pad 5a. 
The terminal 7 soldered to the connection pad 5a is further provided with a 
ball protrusion 7a on the lower surface of the insulating base 1 and when 
connecting the terminal 7 to a wire conductor 8a of an external electronic 
circuit board 8, the ball protrusion 7a functions to make this connection 
easy and reliable. 
The terminal 7 provided with the ball protrusion 7a satisfies D.sub.2 
&lt;D.sub.1a, 0.2 (mm).ltoreq.D.sub.2 .ltoreq.1.0 (mm), d.gtoreq.0.05 (mm) 
0.08.ltoreq.d/D.sub.2 .ltoreq.0.85 when D.sub.1a represents the diameter 
of the ball protrusion 7a, D.sub.2 represents the diameter of the opening 
of the depression 1b, and d represents the depth of the depression 1b. 
This ensures that the terminal 7 is securely hard-soldered to the 
connection pad 5a, the semiconductor integrated circuit element 3 is 
housed inside the hollow part 1a of the insulating base 1, and the package 
is operably mounted on the external electronic circuit board 8. After 
this, heat generated while the semiconductor integrated circuit element 3 
operates is repeatedly applied to both the insulating base 1 and the 
external electronic circuit board 8 and, even though a large thermal 
stress may occur due to the difference of both coefficients of thermal 
expansion between the insulating base 1 and the external electronic 
circuit board 8, this thermal stress is dissipated in the regions around 
both the external periphery of the connection pad 5a and the terminal 7 
positioned in the opening of the depression 1b of the insulating base 1, 
effectively preventing the connection pad 5 from separating from the 
insulating base 1. 
If the diameter D.sub.1a of the ball protrusion 7a of the terminal 7 
becomes smaller than the diameter D.sub.2 of the opening of the depression 
1b of the insulating base 1, it becomes impossible to form the ball 
protrusion 7a on the terminal 7 at a prescribed height thereby making it 
impossible to accurately and strongly join the terminal 7 to the 
designated wire conductor 8a of the external electronic circuit board 8. 
Therefore, the diameter D.sub.1a of the ball protrusion 7a of the terminal 
7 is specified to be larger than the diameter D.sub.2 of the opening of 
the depression 1b of the insulating base 1. 
Furthermore, if the diameter D.sub.2 of the opening of the depression 1b of 
the insulating base 1 is smaller than 0.2 mm, the connection pad 5a and 
the terminal 7 cannot be strongly soldered and, if it is larger than 1.0 
mm, the gap between neighboring depressions 1b will narrow thereby making 
it easy for a contact short-circuit to occur between the ball protrusions 
7a of the neighboring terminals 7 when the terminal 7 having the ball 
protrusion 7a on the lower surface of the insulating base 1 is formed, 
which in turn makes it impossible to form with high density terminals 7 
having the ball protrusion 7a on the lower surface of the insulating base 
1. Consequently, the diameter D.sub.2 of the opening of the depression 1b 
of the insulating base 1 is specified to be within a range from 0.2 mm to 
1.0 mm. 
Further, if the depth d of the depression 1b of the insulating base 1 is 
less than 0.05 mm, when heat generated while the semiconductor integrated 
circuit element 3 operates is repeatedly applied to both the insulating 
base 1 and the external electronic circuit board 8 and, a large thermal 
stress occurs due to the difference of both coefficients of thermal 
expansion between the insulating base 1 and the external electronic 
circuit board 8, it becomes impossible to effectively dissipate this 
thermal stress in the regions around both the external periphery of the 
connection pad 5a and the terminal 7 positioned in the opening of the 
depression 1b of the insulating base 1. Consequently, the depth d of the 
depression 1b of the insulating base 1 is specified to be 0.05 mm or more. 
Continuing further with the relationship between the diameter D.sub.2 of 
the opening of the depression 1b of the insulating base 1 and the depth d 
of the depression 1b, if d/D.sub.2 .ltoreq.0.08, when heat generated while 
the semiconductor integrated circuit element 3 operates is repeatedly 
applied to both the insulating base 1 and the external electronic circuit 
board 8 and, a large thermal stress occurs due to the difference of both 
coefficients of thermal expansion between the insulating base 1 and the 
external electronic circuit board 8, it becomes impossible to effectively 
dissipate this thermal stress in the regions around both the external 
periphery of the connection pad 5a and the terminal 7 positioned in the 
opening of the depression 1b of the insulating base 1 and moreover, if 
d/D.sub.2 .gtoreq.0.85, material inside the depression 1b is absorbed into 
the ball protrusion portion 7a of the terminal 7, which comprises solder, 
results in an incomplete electrical connection between the terminal 7 and 
the connection pad 5a. Consequently, the relationship between the diameter 
D.sub.2 of the opening of the depression 1b of the insulating base 1 and 
the depth d of the depression 1b is specified to be 0.08.ltoreq.d/D.sub.2 
.ltoreq.0.85. 
The terminal 7 having the ball protrusion 7a is formed on the lower surface 
of the insulating base 1 by first filling excessive solder into the 
depression 1a of the insulating base 1 and then fusing this solder at a 
temperature of from about 150.degree. C. to 250.degree. C. In this case, 
the solder protruding from the depression 1a of the insulation base 1 
forms the ball protrusion 7a by surface tension. 
In this way, the package for housing semiconductor elements according to 
the invention becomes a semiconductor device that can be fabricated as a 
product by attaching the semiconductor integrated circuit elements 3 to 
the bottom surface of the depression 1a of the insulating base 1 using an 
adhesive; electrically connecting each electrode of the semiconductor 
integrated circuit elements 3 to the metallized wiring layer 5 by means of 
bonding wires; joining the lid 2 to the upper surface of the insulating 
base 1 using a sealant such as glass or resin; and hermetically sealing 
the semiconductor integrated circuit elements 3 inside a container 4 
consisting of the insulating base 1 and the lid 2. 
A package for housing semiconductor elements of the invention comprises an 
insulating base, which consists of electrical insulation material, the 
insulating base having on the upper surface thereof a mounting portion 
that mounts the semiconductor elements as well as a plurality of 
depressions on either of the upper surface and the lower surface thereof; 
a plurality of metallized wiring layers led away from the periphery of the 
mounting portion and extending to one end surface of the depressions; a 
plurality of connection pads for electrically connecting the metallized 
wiring layers, formed on the end surface of the depressions of the 
insulating base; and terminals which are soldered to the connection pads, 
each terminals forming integrally with the soldered portion, a ball 
protrusion on the surface of the insulating base, and the package is 
characterized in that D.sub.2 &lt;D.sub.1a, 0.2 (mm).ltoreq.D.sub.2 
.ltoreq.1.0 (mm), d.gtoreq.0.05 (mm) 0.08.ltoreq.d/D.sub.2 .ltoreq.0.85 
when D.sub.1a represents the diameter of the ball protrusion, D.sub.2 
represents the diameter of the opening of the depression and d represents 
the depth of the depression. Consequently, the terminal can be securely 
attached by hard-solder to the connection pad, and when the package is 
operably mounted on the external electronic circuit board while 
simultaneously housing the semiconductor integrated circuit element inside 
the package, heat generated while the semiconductor integrated circuit 
element operates is repeatedly applied to both the insulating base and the 
external electronic circuit board and, even though a large thermal stress 
occurs due to the difference of both coefficients of thermal expansion 
between the insulating base of the package and the external electronic 
circuit board, this thermal stress is dissipated in the regions around 
both the external periphery of the connection pad and the terminal 
positioned in the opening of the depression of the insulating base. As a 
result, the connection pads do not separate from the insulating base and 
allow each electrode of the semiconductor integrated circuit elements 
housed inside the package for housing semiconductor elements to be 
accurately electrically connected to a designated external electronic 
circuit over a long period of time. 
FIG. 3 shows another preferred embodiment of the package for housing 
semiconductor elements according to the invention. Similar to FIG. 2, FIG. 
3 is a principal expanded sectional view showing the vicinity of the lower 
surface of the depression 1b of the insulating base 1. As shown in FIG. 1, 
the schematic construction of the package according to this embodiment is 
essentially identical to the previous embodiment. Therefore, detailed 
explanation is omitted with only the different portions being explained 
referring to FIG. 3. 
The connection pad 5a electrically connecting the metallized layer 5 serves 
as a substrate metal layer when the ball terminal 7 is attached to the 
insulating base 1 and the ball terminal 7 is soldered to the surface of 
the connection pad 5a using brazing filler material 8 such as a low 
melting point lead-tin solder with a lead-to-tin weight ratio of 6:4. For 
example, the ball terminal 7 comprises a high melting point lead-tin 
solder with a lead-to-tin weight ratio of 9:1. 
In soldering the ball terminal 7 to the connection pad 5a, D.sub.2 
.ltoreq.D.sub.1b, 0.2 mm.ltoreq.D.sub.2 .ltoreq.1.0 mm, D.sub.1b 
-(D.sub.1b.sup.2 -D.sub.2.sup.2).sup.1/2 .ltoreq.2d are satisfied when 
D.sub.1b represents the diameter of the ball terminal, D.sub.2 represents 
the diameter of the opening of the depression 1b, and d represents the 
depth of the depression 1b. Thereby, the ball terminal 7 is soldered with 
reliable positioning at a designated position on the connection pad 5a 
without being completely embedded inside the depression 1b and only one 
portion protruding while the movement on the connection pad 5a of the ball 
terminal 7 is restricted by the depression 1b. Therefore, because the ball 
terminal 7 is soldered at a designated position on the connection pad 5a 
in the package for housing semiconductor elements, when the ball terminal 
7 is joined to the wire conductor 9b of the external electronic circuit 
board 9, that joint is extremely reliable and secure, thus allowing the 
electrodes of the semiconductor integrated circuit elements 3 housed 
inside the package for housing semiconductor elements to be accurately and 
securely electrically connected to the designated external electronic 
circuit. 
Furthermore, if the diameter D.sub.2 of the opening of the depression 
becomes larger than the diameter D.sub.1 of the ball terminal, the ball 
terminal 7 will be embedded inside the depression 1b of the insulating 
base 1 and will not protrude from the lower surface of the insulating base 
when the ball terminal 7 is soldered to the connection pad 5a. 
Consequently, the diameter D.sub.2 of the opening of the depression 1b is 
specified to be smaller than the diameter D.sub.1 of the ball terminal. 
Furthermore, if the diameter D.sub.2 of the opening of the depression is 
smaller than 0.2 mm, when the connection pad 5a and the terminal 7 are 
soldered, the strength of the solder joint will become weak along with the 
possibility of a cut in the electrical connection between the connection 
pad 5a and the ball terminal 7 occurring easily. Also, if it is larger 
than 1.0 mm, the overall shape of the package for housing semiconductor 
elements will increase in size and preclude itself from being installed in 
an electronic device with increasing compactness when the number of 
electrodes becomes very large in correspondence with the tendency toward 
the high density of the semiconductor integrated circuit elements 3. 
Consequently, the diameter D.sub.2 of the opening of the depression 1b is 
specified to be within a range from 0.2 mm to 1.0 mm. 
Continuing further with the relationship between the diameter D.sub.1b of 
the ball terminal 7, the diameter D.sub.2 of the opening of the depression 
1b and the depth d of the depression 1b, if D.sub.1b -(D.sub.1b.sup.2 
-D.sub.2.sup.2).sup.1/2 .ltoreq.2d, the movement restriction rendered by 
the depression 1b of the ball terminal 7 will be insufficient, making it 
impossible to accurately solder the ball terminal 7 at the designated 
position on the connection pad 5a when the ball terminal 7 is soldered to 
the connection pad 5a. Consequently, the relationship between the diameter 
D.sub.1b of the ball terminal 7, the diameter D.sub.2 of the opening of 
the depression 1b and the depth d of the depression 1b is specified to be 
D.sub.1b -(D.sub.1b.sup.2 -D.sub.2.sup.2).sup.1/2 .ltoreq.2d. 
As previously stated, when the ball terminal 7 comprise a high melting 
point lead-tin solder, the terminal is joined to the wire conductor 9a of 
the external electronic circuit board 9 using a low melting point solder 
such as low melting point lead-tin solder. Then, because the ball terminal 
7 is accurately soldered at the designated position on the connection pad 
5a by means of the depression 1b formed on the connection pad 5a, the 
joint between the wire conductor 9a of the external electronic circuit 
board 9 and the ball terminal 7 is very precise, thereby allowing the 
electrodes of the semiconductor integrated circuit elements 3 housed 
inside the package for housing semiconductor elements to be accurately and 
securely electrically connected to the designated external electronic 
circuit by means of the ball terminals 7. 
In this way, as stated above, the package for housing semiconductor 
elements according to this embodiment can also be fabricated as a 
semiconductor device product. 
Another package for housing semiconductor elements of the invention 
comprises an insulating base, which consists of electrical insulation 
material, the insulating base having on the upper surface thereof a 
mounting portion that mounts the semiconductor elements as well as a 
plurality of depressions on either of the upper surface and the lower 
surface thereof; a plurality of metallized wiring layers led away from the 
periphery of the mounting portion and extending to one end surface of the 
depressions; a plurality of connection pads for electrically connection 
the metallized wiring layers, formed on the end surface of the depressions 
of the insulating base; and ball terminals which are soldered to the 
connection pads, and the package is characterized in that D.sub.2 
&lt;D.sub.1b, 0.2 (mm).ltoreq.D.sub.2 .ltoreq.1.0 (mm), D.sub.1b 
-(D.sub.1b.sup.2 -D.sub.2.sup.2).sup.1/2 .ltoreq.2d when D.sub.1b 
represents the diameter of the ball terminal, D.sub.2 represents the 
diameter of the opening of the depression, and d represents the depth of 
the depression. Consequently, when the ball terminal is soldered to the 
connection pad mounted to the bottom surface of the depression on the 
lower surface of the insulation base, the ball terminal can be soldered 
with reliable positioning at a designated position on the connection pad 
without being completely embedded inside the depression and only one 
portion protruding while the movement on the connection pad of the ball 
terminal is restricted by the depression. As a result, when the ball 
terminal of the package for housing semiconductor elements is joined to 
the wire conductor of the external electronic circuit board, that joint is 
very reliable and secure, thus allowing the electrodes of the 
semiconductor integrated circuit elements housed inside the package for 
housing semiconductor elements to be accurately and securely electrically 
connected to the designated external electronic circuit. 
Although this invention has been described by way of several embodiments 
thereof, it should be realized that many alternatives, modifications, and 
variations will be apparent to those skilled in the art of the foregoing 
description. Accordingly, it is intended to embrace all such alternatives, 
modifications, and all variations as falling within the spirit and broad 
scope of the appended claims.