JPH02129955A - Packaging structure of semiconductor chip - Google Patents

Abstract

PURPOSE:To assure high density packaging by directly connecting electrodes of two semiconductor chips, and directly connecting a remaining electrode of the one semiconductor chip to a pad formed on the surface of a circuit board located in the vicinity of one end surface of the same. CONSTITUTION:Parts 1e-1h of an electrode group formed on one surface of a first semiconductor chip 1 are directly connected electrically and mechanically to pads 3a-3d formed on the surface of a circuit board 3 located in the vicinity of one end surface of the same. Remaining electrodes 1a-1d of the first semiconductor chip 1 project outwardly with respect to the circuit board 3 from one end surface of the same, and electrodes 2a-2d formed on a second semiconductor chip 2 are directly connected to the remaining electrodes 1a-1d electrically and mechanically. Accordingly, an interwiring distance between chips 1, 2 becomes minimum and the flexibility of a wiring position among the respective members 1, 2, 3 are increased. Hereby, packaging can be made high density.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a structure for mounting semiconductor chips on a circuit board, and in particular, a structure suitable for mounting chips such as semiconductor optical sensors and semiconductor X-ray sensors. Regarding structure.

<Prior art> Generally, there are two methods for mounting semiconductor chips such as IC chips on a circuit board: one is to mount the chip in a package, and the other is to mount the chip directly on the circuit board as a pair without using a package. Although there are methods for mounting on a chip, bare chip mounting is more advantageous from the viewpoint of high-density mounting.

Conventional methods for mounting paired chips include wire bonding, TAB (tape automated bonding), and flip-chip bonding, with flip-chip bonding being particularly suitable for high-density packaging.

<Problems to be Solved by the Invention> By the way, even in the flip-chip bonding method, which allows for the highest density packaging, for example, two IC chips are mounted on a substrate and these chips are electrically connected to each other. If it is necessary to do so, it is necessary to provide wiring for the connection on the board, and there is a limit to how short the wiring distance can be. For example, as shown in FIG. 4, two IC chips 41 and 42 are mounted on a substrate 43 by flip-chip bonding, and the electrode 41a of the IC chip 41 is
When interconnecting the electrode 32a of the IC chip 42, the minimum wiring distance on the substrate 43 is required.

As this wiring distance becomes longer, various problems arise, such as an increase in wiring capacitance and resistance, an increase in crosstalk, a decrease in the element's load driving ability, a deterioration in processing speed, signal attenuation, and an increase in noise. .

In order to solve such problems, the applicant has already devised a mounting structure as shown in FIG.
No. 16427). That is, two semiconductor chips 51 and 52 are placed with their electrode forming surfaces facing each other, and the corresponding electrodes are spaced apart (51a and 52b, 51b and 52c).

51c and 52d) by direct soldering, a hole 53c is made in the substrate 53, and with one semiconductor chip 51 accommodated in the hole 53c, the remaining electrodes 52a and 52e of the other semiconductor chip 52 are connected. It has a structure in which it is directly connected to a pad on the substrate 53 by soldering.

With this structure, the electrodes between the chips 51 and 52 are directly connected to each other without going through the wiring on the substrate 53, and the wiring distance between the chips is minimized. Since the other chip 52 is mounted on the hole 53c of the substrate 53 while being fitted into the hole 53c, the mounting density is also more advantageous than the conventional flip-chip bonding method.

However, when such a structure is applied to, for example, a semiconductor photodetector, the chip 51 in FIG. 5 is used as a sensor chip, and the chip 52 is used as its IC amplifier. Furthermore, it is not possible to combine a large number of such structures into a large-area sensor. In other words, only as many detectors as the number of elements that can be formed on one sensor chip 51 can be made.

Further, as the chip 52 which is an IC amplifier, a St chip is usually used, and its thermal conductivity is poor.

On the other hand, various single semiconductors or compound semiconductors are often used as the sensor chip 51, and are extremely sensitive to temperature, and the structure shown in FIG. 5 has a drawback in terms of heat dissipation.

The present invention has been made in view of these points, and it is possible to minimize the wiring distance between two chips, and to increase the detection surface area when applied to a photodetector or an X-ray detector. The purpose is to provide a mounting structure that allows easy heat dissipation measures.

Means for Solving the Problems> A configuration for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment.
Pads 3a, 3b, 3 formed on the surface near one end surface of
c, 3d, a part le of the electrode group formed on one surface of the first semiconductor chip 1;

ff, 1g, and lh are directly electrically and mechanically connected, and the remaining electrodes 1a of this first semiconductor chip 1,
lb, 1c, ld protrude outward from one end surface of the circuit board 3, and the remaining electrodes 1a, lb, lc, l
d, electrodes 2a, 2 formed on the second semiconductor chip 2
b, 2c, 2d are characterized by being directly electrically and mechanically connected.

In addition, in this specification, being directly electrically and mechanically connected refers to a state in which the connection causes electrical continuity and mechanically fixes each other; for example, the electrodes to be connected This refers to fixing the parts by direct soldering or by using conductive adhesive, etc.

Action> Between the corresponding electrodes 1a of the first and second semiconductor chips 1 and 2
and 2a, lb and 2b, etc. are directly connected to each other without using wiring on the substrate 3, and the inter-chip wiring distance is minimized. Further, since the second semiconductor chip 2 is disposed on the side of the end surface of the circuit board 3, each member L 2, 3
For example, as shown in Fig. 2, cooling pipes 10 etc. can be installed as needed to control the temperature, or as shown in Fig. 3, by stacking the This facilitates applications such as increasing the detection surface area.

<Example> FIG. 1 is a side view of an embodiment of the present invention.

In this example, the second semiconductor chip 2 has a diameter of 0.4 mm.
It is a minute semiconductor sensor chip in which 16 pixels of 4×4 are formed at a pitch. The first semiconductor chip 1 also includes an IC for signal processing of the output of the sensor chip 2.
This is an St chip, which is a chip in which transistors and the like are integrated to form an amplifier and the like.

Further, the circuit board 3 is used to connect the first semiconductor chip 1 to an external circuit or to perform further signal processing such as A-D conversion of the detection signal outputted via the first semiconductor chip 1. This is a board on which chips and ICs are mounted.

Now, the first semiconductor chip 1 has electrodes 1a to 1d for connecting to the second semiconductor chip 2 and electrodes 1e to 1h for connecting to the circuit board 3, respectively, on both sides on the same surface. are formed together. And electrode i
a, lb, lc and 1d, the second semiconductor amplifier 2
The electrodes 'la, 2b, 2c and 2d formed on the electrodes are directly interconnected by solder S...S, respectively. Further, the electrodes 1e, If, Ig and 1h are provided with pads 3 formed on the surface close to one end surface of the circuit board 3.
A, 3b, 3c and 3d are similarly directly connected to each other by solder S...S.

As a result, the second semiconductor chip 2 is supported on the side of the circuit board 3 via the first semiconductor chip 1.

The structure as described above can be manufactured by the following procedure.

First, after forming solder bumps on each of the electrodes 1a to 1h of the first semiconductor chip 1, each electrode 2a to 2d of the second semiconductor chip 2 and each pad 3a to 3d of the circuit board 3 are respectively applied. Position them so that they touch each other, and reflow the solder to melt and solidify it.

Alternatively, bumps of high melting point solder are formed on the electrodes 1a to 1d and bumps of low melting point solder are formed on the electrodes 18 to 1h, respectively, and first, each of the electrodes 2a to 2 of the second semiconductor chip 2 is
d to the electrodes 1a to 1d and connected by high temperature reflow, then each pad 3a to 3d of the circuit board 3 is connected to the electrode 1e.
It is also possible to connect by low-temperature reflow after positioning at 1 h.

Note that if each chip is lightweight, a conductive adhesive may be used instead of the solder S...S.

According to the present invention having the basic structure as described above, the following applications are possible.

In the example shown in FIG. 2, a cooling pipe 4 with a diameter of about 1 n+ is arranged directly above the first semiconductor amplifier 1 and extends between the second semiconductor amplifier 2 and the circuit board 3. It is bonded with a good adhesive 5.

By passing a refrigerant such as water through this cooling pipe 4,
The first semiconductor chip 1 on which the Si integrated circuit serving as the heat source is formed can be effectively cooled, and the influence of temperature on the semiconductor sensor chip 2 can be reduced.

In the example shown in FIG. 3, multiple sets of the structure shown in FIG. By arranging them continuously, a large-area surface sensor device can be obtained.

In this example, if a film-like flexible printed circuit board is used as each circuit board 3 . . . 3 , the laminated thickness is thin (so that the sensor chips 2 . . . 2 can be arranged almost in a plane).

<Effects of the Invention> As explained above, according to the present invention, the electrodes of two semiconductor chips are directly connected by solder or a conductive adhesive, and the remaining electrode of one semiconductor chip is
Since it is connected directly to a pad formed on the surface near one end of the circuit board using solder or conductive adhesive, the wiring distance between the two chips is minimized, and there is almost no wiring capacitance, improving performance. Higher density mounting is possible compared to flat mounting.

Moreover, since the semiconductor chip is placed on the side of one end surface of the circuit board, when applied to semiconductor sensors, it is possible to increase the sensor area by combining multiple chips, and to control temperature by placing cooling pipes. This makes it possible to improve the function and performance of the sensor.

In addition, no solder bumps are formed on the sensor chip (second semiconductor chip), and the Si chip (first semiconductor chip)
Since interconnections can be made by forming solder bumps only on the sides, there is no risk of contamination associated with bump formation when the sensor chip is a compound semiconductor. That is, when compound semiconductors are immersed in a plating bath during the process of forming solder bumps, they may react with the plating solution and cause performance deterioration, but this process can be omitted.

[Brief explanation of drawings]

FIG. 1 is a side view of an embodiment of the present invention, FIGS. 2 and 3 are side views showing application examples thereof, and FIG. 4 is a side view of two semiconductor chips mounted by the conventional flip-chip bonding method. Explanatory Diagram of Connection FIG. 5 is an explanatory diagram of the mounting structure proposed in Japanese Patent Application No. 116427/1982. 1... First semiconductor chip 1a to 1h... Electrodes 2a to 2d 3a to 3d S...S

Claims (1)

[Claims] On the pad formed on the surface near one end of the circuit board,
A part of the electrode group formed on one surface of the first semiconductor chip is directly electrically and mechanically connected, and
The remaining electrodes of the semiconductor chip protrude outward from the one end surface with respect to the circuit board, and a second electrode is provided on the remaining electrodes.
A semiconductor chip mounting structure in which electrodes formed on a semiconductor chip are directly electrically and mechanically connected.