Semiconductor device package side-by-side stacking and mounting system

The invention is to an array of stacked devices utilizing vertical surface mounted semiconductor devices stacked side by side and inserting the stack of devices into a casing. The packaged stack of devices creates a cube package which is capable of replacing SIMM boards, and saves considerable space. The casing dissipates heat generated in the devices, and may be of metal or thermally conductive plastic.

FIELD OF THE INVENTION 
This invention relates to semiconductor devices, and more particularly to a 
mounting the stacked packages onto a circuit board. 
BACKGROUND OF THE INVENTION 
Memory devices used, particularly in computers, are arrayed on the computer 
circuit board, or mounted on small circuit boar& to group encapsulated 
memory device packages into a distinct amount of memory capacity. For 
example, SIMM (Semiconductor Integrated Memory Module) devices, utilize 
several memory device packages interconnected on a small circuit board to 
form memory modules. The devices comprise integrated circuit memory chips 
encapsulated into discrete protective packages, with electrical 
connections established by soldering exposed chip contact leads onto 
corresponding contacts of the circuit board. The sockets into which the 
memory circuit boards are mounted on the computer circuit board occupy 
considerable space, especially if the computer is to be designed to 
utilize 4-Mbytes or more of memory. As computer boards become more 
complex, and additional functions are integrated into fie computer circuit 
board, the space required for individual memory devices and SIMM modules 
needs to be reduced to accommodate other circuitry. 
SUMMARY OF THE INVENTION 
The invention is to an array of stacked devices utilizing vertical surface 
mounted semiconductor devices stacked side by side and inserting the stack 
of devices into a casing. The packaged stack of devices creates a cube 
package which is capable of replacing SIMM boards, and saves considerable 
space. The casing dissipates heat generated in the devices, and may be of 
metal or thermally conductive plastic. 
The casing has two side clips which clip directly onto the circuit board on 
which the devices are to be mounted. The devices, which normally are 
attached to a circuit board by solder reflow, may be tightly damped to 
contact pads on the circuit board, avoiding the necessity to solder the 
devices to the circuit board, and allowing the devices to be removed, when 
defective, without the need to remove a solder connection. Larger memory 
arrays are possible in a smaller space by stacking or joining a number of 
arrays together. 
The technical advance represented by the invention as well as the objects 
thereof will become apparent from the following description of a preferred 
embodiment of the invention when considered in conjunction with the 
accompanying drawings, and the novel features set forth in the appended 
claims.

DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 shows a vertical surface mount device 1 which comprises an 
encapsulated integrated circuit memory chip having generally planar and 
parallel, rectangular front and rear side faces 2, 3 and a plurality of 
contacts 11 extending out from a bottom edge 4 of the packaged device. 
Device 1 is usually flow soldered onto a circuit board having a contact 
pad for each contact 11. 
FIG. 2 shows an array 10 of nine identical vertical surface mount devices 
stacked horizontally together, side by side with their side faces 2, 3 
brought into adjacent superposed relationships so that a front face 2 of 
one device 1 abuts a rear face 3 of a neighboring device 1 and so that 
their bottom edges 4 are aligned in a common plane with the contacts 11 of 
each device packages extending out of the bottom of stack 10 of the 
arrayed devices. More or fewer device packages may be encased, depending 
upon the particular application. A case 12 is shown positioned above the 
horizontally arrayed device packages. Case 12 is placed over devices 1 and 
encloses them as illustrated in FIG. 3. As shown, case 12 has a generally 
rectangular bottom parallelepiped box-like construction, with a bottom 
opening internal cavity 5 (see FIG. 4) defined by internal surfaces of 
top, front and rear end, and right and left side walls 6, 7, 8. The 
dimensions of cavity 5 are chosen so that the open bottom of case 12 can 
be placed over the array 10, to bring the top, ends and sides of array 10 
into corresponding abutment with top, end and side surfaces 6, 7, 8 of 
cavity 5, leaving contacts 11 exposed and accessible through the open 
bottom of case 12. There are two clips 13, only one shown in FIG. 3, 
located in spaced positions, attached to respective opposite sides 8 of 
case 12. The clips 14 have depending leading ends 9 which are inserted 
respectively into correspondingly spaced holes in a circuit board, 
described below, to hold the case and arrayed device packages in contact 
with contact pads on a circuit board. The clips are made, for example from 
a spring-leaf material, and have a V-noah 13a for securing the clips by 
snap action within the holes in the circuit board. 
FIG. 4 shows an end view of the arrayed packaged deuces 1 in a case 12, 
with a potion of the case cut away to show the packaged devices in case 
12. Contact 11, which extend below the bottom of case 11, are in contact 
with circuit board 14. Clip 13 extends through a hole in circuit board 14. 
FIG. 5 is a side view of the encased array 10 of packaged deuces 1. Case 12 
conforms at an angled cut-off top corner edge 12a with a correspondingly 
angled top edge of the stacked array 10 defined by aligned chambered edges 
1a of the package exteriors of deuces 1, as shown in FIG. 1. The 
conforming of an angled top corner of case 12 with the corresponding 
aligned angled chamfered edges of the package exteriors of devices 1 helps 
hold devices 1 in position within case 12 and present more surface area of 
each deuce package in contact with the case. This is important since case 
12 also serves as a heat sink for the cased devices. Case 12 may be either 
metal or a thermally conductive plastic to assist in dissipating heat 
generated by the devices. Both clips 13 are shown in FIG. 5. The two clips 
securely hold case 12 over packaged devices 1 against a circuit board on 
which the packaged deuces are mounted. 
FIG. 6 shows four sets of cased deuces. As an example, if deuces 1 are 
1-Mbyte memory devices, each cased array 10 represents a 9.times.1-Mbyte 
array, providing 1 Mbyte of memory. Eight deuces are needed to provide a 
1-Mbyte.times.8-bit memory. Eight devices in a case provide provide the 
1-Mbyte.times.8-byte memory array. The ninth clip provides a ninth bit for 
parity. The four cased arrays 10 then provide 4 Mbytes of memory, which is 
commonly used in computer systems. 
FIG. 7 shows the top of a circuit board 23 with contacts 32 arrayed for the 
four cased arrays in FIG. 6. In the illustrated example, each packaged 
device has 16 pins. Therefore, to provide contacts to each pin on each 
chip, an array of 16.times.9 contacts is needed for each cased array. In 
practice, the mounting area required by the four cased arrays is less than 
the space required by four SIMM modules. 
Circuit board 23 has four sets of holes 24-31, one set for each 16.times.9 
array of Contacts. Clips 19-22 lock in holes 25-31 and another set of 
clips (not illustrated) lock into holes 24-30, to hold cased arrays 15-18 
on circuit board 23. When the clips are locked into the holes on circuit 
board 23, sufficient down-pressure is exerted on the device packages to 
hold the device contacts in electrical contact with contact pads 32. 
Therefore, it is not necessary to flow solder the contacts on the devices 
to the contact pads on the circuit board.