JP2001044326A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a semiconductor device against disconnections due to warpage of a sealing body. SOLUTION: A group of inner terminals 14 and a group of outer terminals 15 are each formed on the upper and lower surfaces of a base 11 of a BGA/IC 31, where the inner terminals 14 and the outer terminals 15 are connected electrically together with electrical wirings 17. A semiconductor pellet 26 bonded to the top surface of the base 11 is connected electrically to the inner terminals 14 with wires 28. Solder bumps 21 are provided protruding to the outer terminals 15, which are out of the outer terminals provided on the under surface of the base 11 and located in an intermediate region, and pins 18 which are higher than the solder bumps 21 are provided, protruding to the outer terminals arranged on the outer peripheral part of the under surface of the base 11. At this point, since the pins 18 are anchored to through-holes provided to the a mounting board, the base 11 is prevented from warping due to heat released at mounting of a mounting board. Therefore, connection terminals can be protected against breakage due to solder bumps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing technique, and more particularly, to the mounting of a semiconductor integrated circuit device (hereinafter, referred to as IC) having a ball grid array package (hereinafter, referred to as BGA). Regarding effective technology to use.

[0002]

2. Description of the Related Art As the number of pins increases, ICs and tapes having a quad flat package (QFP) have been developed.
In a package such as an IC provided with a carrier package (TCP) that takes out outer leads (external terminals) from a peripheral portion, the pitch is narrowed, so that the package is approaching a manufacturing limit and a board assembly limit. Accordingly, a BGA has been proposed as a package that realizes a large number of pins (high density of external terminals) without increasing the size by arranging the external terminals on the entire main surface of the sealing body.

That is, an IC provided with this BGA
(Hereinafter referred to as BGA IC) is a wiring board (in which an internal terminal group and an external terminal group are formed on a front main surface and a rear main surface, respectively, and each internal terminal and each external terminal are electrically connected to each other. A semiconductor pellet is bonded to the main surface of the wiring substrate on the side on which the internal terminals are formed, and is electrically connected to the internal terminal group by bonding wires. Each external terminal exposed on the opposite main surface of the wiring board is provided with a solder bump.

[0004] The mounting of the BGA-IC on the mounting board is performed by applying a solder to each land of the mounting board via a flux and then heating and performing a reflow soldering process. . In other words, the connection terminals are formed by curing the solder bumps melted by heating between the external terminals and the lands.
The IC is mechanically and electrically connected to the mounting board by the connection terminal group.

[0005] As an example describing BGA IC, see "VLSI Packaging Technology (Lower)" published by Nikkei BP Co., Ltd., published on May 31, 1993, pages P173 to P173.
178.

[0006]

However, the aforementioned BG
In A-IC, the wiring board is warped so that the outer peripheral side is separated from the mounting board due to heat generated during operation after mounting on the mounting board and thermal stress or mechanical stress caused by a temperature cycle test, etc. There is a case where disconnection due to breakage occurs in connection terminals arranged in the outer peripheral portion.

An object of the present invention is to provide a semiconductor device manufacturing technique capable of preventing disconnection due to warpage.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0009]

The outline of a typical invention among the inventions disclosed in the present application is as follows.

That is, in a semiconductor device in which an external terminal group is arranged on one main surface of a rectangular flat plate-shaped sealing body in which a semiconductor pellet is sealed, and solder bumps are projected from each external terminal. A plurality of pins are protruded from the one main surface of the sealing body at positions separated from each other.

For example, the mounting of the semiconductor device on a mounting board is performed by performing a flow soldering process after each pin is inserted into a through hole of the mounting board.
Even if mechanical stress that causes warping of the sealing body due to thermal stress after mounting is applied, the occurrence of warpage is suppressed or suppressed because the sealing body is mechanically and firmly connected to the mounting board by the pins. You. Therefore, occurrence of disconnection due to breakage of the external terminal in the outer peripheral portion can be prevented.

[0012]

1A and 1B show a BGA IC according to an embodiment of the present invention. FIG. 1A is a partially cut plan view of an upper half, a bottom view is a lower half, and FIG. It is sectional drawing.
FIG. 2 et seq. Are explanatory diagrams for describing a method of manufacturing a BGA IC according to an embodiment of the present invention.

In the present embodiment, the semiconductor device according to the present invention is a package in which the number of pins can be increased while the size of the package is kept small, and furthermore, the surface mountable B
GA, functionally CPU or MPU
As a semiconductor integrated circuit device (IC). The BGA IC is configured as shown in FIG.

That is, the BGA IC 31 includes a semiconductor pellet (hereinafter, referred to as a pellet) 26 in which a CPU or MPU is built in a so-called pre-process and diced into a square plate shape. Also, BGA / IC
31 is a hermetic sealing body 30 and a group of pins 18 and solder bumps 2
A hermetic sealing body 30 includes a base 11 and a cap 29. On the base 11, a group of internal terminals 14 and a group of external terminals 15 and 16 are formed on the front main surface and the rear main surface, respectively, and each internal terminal 14 and each external terminal 15 and 16 are electrically connected by an electric wiring 17. Connected. Internal terminal 1 of base 11
A semiconductor pellet 26 is bonded to a main surface (hereinafter, referred to as an upper surface) on the side on which the substrate 4 is formed.
It is electrically connected to the group of internal terminals 14 by wires 28. Solder bumps 21 are protruded from external terminals 15 disposed on the intermediate region of the external terminal group exposed on the lower surface of base 11. Each of the external terminals 16 arranged on the outer peripheral portion of the lower surface of the base 11 is provided with a respective pin 18 having a length equal to or greater than the height of the solder bump. The ground terminal and the power supply terminal of the semiconductor pellet 26 are electrically connected to one of the pins 18. The BGA IC 31 according to the above configuration is manufactured by the manufacturing method described below.

Hereinafter, a BGA-type according to an embodiment of the present invention will be described.
A method for manufacturing an IC will be described. With this description, the details of the configuration of the BGA-IC will be clarified.

FIG. 2 shows a method of manufacturing the above-mentioned BGA IC.
The base 11 shown in FIG. As shown in FIG. 2, the base 11 is formed into a substantially square flat plate shape using alumina as an insulating ceramic material, and a cavity 12 is formed at the center of the upper surface of the base 11. Are laid down concentrically. The cavity 12 is formed in a three-stage hole shape in which large, medium, and small substantially square holes are concentrically overlapped. A bonding floor 13 for bonding semiconductor pellets is laid on the bottom surface of the cavity 12. A large number of rectangular internal terminals 14 are formed on the step surface of the lower and middle steps of the cavity 12 so as to be aligned in a line in the longitudinal direction of each side. By the way, the bonding floor 13 and the internal terminals 14
Is formed by metallizing a nickel (Ni) film or a gold (Au) film.

An external terminal for pin connection (hereinafter referred to as an external terminal for pin) 1 is provided at a peripheral portion on a lower surface of the base 11.
5 are formed at equal intervals in the circumferential direction. A plurality of solder bump connection external terminals (hereinafter, referred to as bump external terminals) 16 are arranged in a matrix on the lower surface of the base 11 inside the group of pin external terminals 15. The external terminals 15 for pins and the external terminals 16 for bumps are electrically connected to the internal terminals 14 by electric wires 17.
Although not shown in FIG. 2, at least some of the pin external terminals 15 are electrically connected to the ground terminal and the power supply terminal of the group of internal terminals 14.

As shown in FIG. 3, the pins 18 are mechanically and electrically connected to the pin external terminals 15 of the base 11 with the pins 18 arranged vertically. FIG.
(C) shows a butting method which is an example of a method of connecting a pin to an external terminal. In FIG. 4A, the pin external terminal 15 is formed of tungsten (W), and a nickel (Ni) film 15a is applied to the surface thereof. As shown in FIG.
Is formed in a needle shape (pin shape) having a disk-shaped flange portion 18a at the upper end, and silver brazing (silv) is performed with the upper surface of the flange portion 18a abutting against the lower surface of the external terminal 15 for pins.
er-alloy brazing)
9. Thereafter, as shown in FIG. 4C, a gold (Au) coating 20 is applied to the surfaces of the pin external terminals 15, the pins 18, and the silver brazed portions 19. However, the illustration of the Ni coating 15a and the Au coating 20 is omitted outside FIG.

As shown in FIG. 3, solder bumps 21 are mechanically and electrically connected to the bump external terminals 16 of the base 11. FIGS. 4D to 4F show an example of a method of connecting solder bumps to external terminals. FIG.
In (d), the bump external terminal 16 is formed of tungsten, and the surface thereof has a Ni coating 16a.
And an Au coating 16b are sequentially applied. FIG.
As shown in (e), a solder ball 22 is adhered to the bump external terminal 16 by a flux 23. The solder ball 22 is formed in a spherical shape by a solder material used for a normal reflow soldering mounting operation.
In this state, when the solder ball 22 is heated and melted and then cooled and solidified, a substantially spherical solder bump 21 is applied to the bump external terminal 16 by surface tension as shown in FIG. It is in a formed state.

Here, as shown in FIG. 4, the value of the length L of the pin 18 from the lower surface to the lower end of the base 11 is
The height H of the solder bump 21 from the base 11 to the lower end is set to be larger than the value H, that is, L> H.
Further, in the present embodiment, the value of the length L of the pin 18 is larger than the sum of the value of the height H of the solder bump 21 and the value of the depth D of the through hole of the mounting board described later, that is, L > (H + D).

In the pellet bonding step and the wire bonding step, pellet bonding and wire bonding are performed on the base 11 configured as described above, and the assembly 24 shown in FIG. 5 is manufactured.

First, in the pellet bonding step, the pellets 26 face up on the bonding floor 13 on the bottom surface of the hole of the cavity 12 of the base 11 (a state in which the main surface on the active area side faces the side opposite to the bottom surface of the hole). It is arranged and bonded by the bonding layer 25. A plurality of electrode pads 27 are formed on the main surface of the pellet 26 on the side opposite to the bonding surface, and are arranged in a ring around the outer periphery. The bonding layer 25 is preferably formed of a silver paste, but may be formed of a gold-silicon eutectic layer or a high melting point solder material.

Next, in the wire bonding step,
A wire 28 is bridged between each electrode pad 27 of the pellet 26 and each internal terminal 14 of the base 11.
The wire bonding is preferably performed by an ultrasonic bonding method, but may be performed by an ultrasonic thermocompression bonding method or the like. When performing the pellet bonding and the wire bonding, it is desirable to prevent damage such as bending of the pin 18 and crushing of the solder bump 21 by using a carrier jig (not shown).

In the assembly 24 manufactured as described above, the integrated circuit of the pellet 26 is connected to the pin 18 and the solder bump 21 through the electrode pad 27, the wire 28, the internal terminal 14, the electric wiring 17 and the external terminals 15 and 16. It will be in the state of being pulled out electrically. Here, the pellet 26
In the group of electrode pads 27, the ground electrode and the power supply electrode are electrically connected to at least some of the pin external terminals 15, and the electrode pads 27 of the pellet 26 are formed.
Most of the signal electrodes in the group are electrically connected to the bump external terminals 16.

Thereafter, the cap 2 is placed on the upper surface of the base 11.
9 is sealed so as to close the cavity 12 and is welded with a low-melting glass or the like, and hermetically seals the pellet 26, the internal terminals 14 and the wires 28 as shown in FIG. The body 30 is formed. Thus, the BGA IC 31 shown in FIG. 1 is manufactured.

The BG manufactured and configured as described above
The A.IC 31 is mounted on a mounting board 40 and used as shown in FIG.

The mounting substrate 40 shown in FIG.
A substrate main body 41 formed in a square flat plate shape sufficiently larger than the IC 31 is provided, and the substrate main body 41 is formed using an insulating substrate having an insulating property such as a glass epoxy resin substrate. A plurality of through holes 42 are provided in the substrate body 41 in a substantially square frame shape so as to correspond to the group of pins 18 of the BGA / IC 31 and are opened in the thickness direction. Each through hole 42 is formed by covering a conductor layer made of a conductive material such as copper on the opening end surface and the inner peripheral surface of a cylindrical through hole substantially equal to the outer diameter of the pin 18. The surface has been subjected to a surface treatment to enhance solderability.

A large number of lands 43 are formed in a matrix shape so as to correspond to the solder bumps 21 of the BGA / IC 31 in an area inside the square frame of the through holes 42 on the upper surface of the substrate main body 41. ing. Each land 43 is made of a conductive material such as copper and is formed in a circular flat plate shape having a size substantially equal to that of the external terminal 16 for bumps, and the surface thereof is subjected to a surface treatment for enhancing solderability. ing. Although not shown, an electric wiring is connected to each through hole 42 and each land 43, and each through hole 42 and each land 43 are connected to the connector of the mounting board 40 by each electric wiring, Electronic components and electronic devices. In particular, some of the through holes 42 are connected to a ground terminal and a power terminal.

Next, a method of mounting the BGA IC 31 having the above-described configuration on the mounting board 40 will be described.

When the BGA IC 31 is mounted on the mounting board 40, the pins 18 of the BGA IC 31 are inserted into the through holes 42 of the mounting board 40 from above. Here, since the length L of the pin 18 is connected such that L> (H + D), the lower end of the pin 18 inserted into the through hole 42 projects from the lower end of the through hole 42. When each of the pins 18 is inserted into each of the through holes 42, the BGA / IC 31 is held by the mounting board 40, and the solder bumps 21 of the BGA / IC 31 are aligned with the respective lands 43 and abutted. It will be in the state that was done.

In this holding state, when the assembly of the BGA IC 31 and the mounting board 40 is subjected to the flow soldering process, a soldering portion 44 is provided between each pin 18 and each through hole 42.
Is formed. Here, since the lower ends of the pins 18 project from the lower ends of the through holes 42, the soldering portions 44 are also formed on the lower surface side of the mounting board 40. In addition, each solder bump 21 is solidified after being melted, so that a connection terminal 45 is formed between each bump external terminal 16 and each land 43. The BGA IC 31 is mechanically and electrically connected to the mounting board 40 by the pins 18 and the connection terminals 45, and the BGA IC mounting structure 46 shown in FIG. 6A is manufactured. It will be.

Next, the operation will be described.

The BGA-IC mounting structure 46 according to the above-described structure manufactured as described above is subjected to a final inspection before shipment. As a final inspection, an environmental test including a temperature cycle test and a thermal shock test is performed. Also, BGA ・ I
C31 repeats temperature rise and cooling during its operation.

As described above, when thermal stress is applied to the mounting structure 46 of the BGA / IC according to the environmental test or actual operation, each connection terminal is expanded and contracted due to a difference in thermal expansion coefficient between the BGA / IC 31 and the mounting board 40. 45 is subjected to mechanical stress. Here, since the connection terminal 45 is formed of a solder material that is easily plastically deformed, mechanical stress accompanying expansion and contraction can be absorbed by the plastic deformability of the solder material.

When a thermal stress is applied to the mounting structure 46 of the BGA / IC according to the above-described environmental test or actual operation, the hermetic sealing body 30 warps so that the outer peripheral portion is separated from the mounting substrate 40. As shown in FIG. 6B, all the BGA ICs are connected to the mounting substrate 45 as shown in FIG.
In the mounting structure 47 of the BGA / IC mechanically and electrically connected by the above, a broken portion 48 may be generated at the connection terminal 45 in the outer peripheral portion.

That is, the connection terminal 45 formed of a solder material that is easily plastically deformed can absorb mechanical stress due to a difference in thermal expansion coefficient. However, as shown in FIG. When this occurs, since the plastic deformation limit of the connection terminal 45 is exceeded, a break 48 is generated in the connection terminal 45.

On the other hand, the BGA according to the present embodiment
In the IC mounting structure 46, the pins 18 arranged on the outer periphery of the hermetic sealing body 30 are soldered to the through holes 42 of the mounting board 40 by the soldering portions 44, so that the hermetic sealing is performed. Warpage in which the outer peripheral portion of the body 30 separates from the mounting board 40 is prevented. That is, each pin 1
8 is anchored to the through-hole 42 by the soldering portion 44, so that the warp deformation of the hermetic sealing body 30 is prevented. Here, the soldering part 4
In the case where 4 is formed on the lower surface side of the mounting substrate 40, the anchor is firmly anchored, so that warpage is more reliably prevented.

Even if the outer peripheral portion of the hermetically sealed body 30 is warped, the pins 18 slide and break with respect to the through-holes 42, so that the soldering portions 44 of the pins 18 have defects due to breakage. This can be prevented.

According to the above embodiment, the following effects can be obtained.

1) By disposing pins separately from the solder bumps on the outer peripheral portion of the BGA sealing body, a mounting structure in which the BGA / IC is mounted on a mounting board can be used for an environmental test of the mounting structure. In addition, since the sealing body can be prevented from warping due to thermal stress during operation or during operation, it is possible to prevent the occurrence of disconnection failure due to breakage in the external terminals in the peripheral portion.

2) Even if a warp occurs in the hermetic sealing body, the pin slides in the through hole, so that the contact with the through hole can be maintained. Can be prevented.

3) According to the above 1) and 2), the quality and reliability of the mounting structure in which the BGA / IC is mounted on the mounting substrate can be improved, and the life can be extended.

4) By setting the length L of the pins to be L> (H + D), the pins can be firmly anchored in the through holes, so that the warpage of the sealing body can be prevented more reliably. be able to.

5) By electrically connecting the ground terminal and the power supply terminal to the pin, a relatively large current can flow since the contact area is large and the electric resistance is small.

FIG. 7 shows a BGA · I according to an embodiment of the present invention.
C is shown.

This embodiment is different from the above embodiment in that
The point is that the pin 18 is also provided at the intermediate portion of the hermetic sealing body 30.

In the BGA IC 31A according to the present embodiment, since the pins 18 are also provided at the intermediate portion of the hermetic seal 30, the outer peripheral portion of the hermetic seal 30 is warped away from the mounting substrate. Generation can be reliably prevented, and warpage in which the central portion separates from the mounting substrate can also be prevented.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.

For example, the pins are not limited to being disposed annularly in the sealing body, but may be disposed at four corners or other places.

The electrical connection between the base and the pellet is not limited to the wire bonding method, but may be a flip chip method or a tape automated bonding (TA).
B) Batch bonding (gang bonding) such as method
A method may be used.

The sealing body for sealing the pellets, internal terminals, wires and the like is not limited to a hermetic sealing body but may be a resin sealing body.

The pins and the solder bumps are not limited to projecting before the pellet is bonded to the sealing body, but may be projecting after the pellet is bonded to the sealing body.

The shape of the pellet, the sealing body and the mounting substrate is not limited to a square, but may be a rectangle or the like.

In the above description, the CPU, which is a field of application in which the invention made mainly by the present inventor is the background, has been described.
And the case where the present invention is applied to an IC in which an MPU is built has been described. However, the present invention is not limited to this.
The present invention can be applied to all semiconductor devices in which an SI, a logic circuit, and the like are built.

[0055]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

By disposing pins separately from the solder bumps on the outer periphery of the sealing body, the sealing body warps due to thermal stress during an environmental test or operation of the mounting structure of the semiconductor device. Therefore, it is possible to prevent the occurrence of disconnection failure in the external terminals in the peripheral portion.

[Brief description of the drawings]

1A and 1B show a BGA IC according to an embodiment of the present invention, in which FIG. 1A is a partially cut plan view of an upper half, a bottom view is a lower half, and FIG.

FIGS. 2A and 2B show a base used in a method of manufacturing a BGA IC according to an embodiment of the present invention, wherein FIG. 2A is a plan view of an upper half and a bottom view of a lower half, and FIG. It is a front sectional view.

3A and 3B show a base after connection of pins and solder bumps, wherein FIG. 3A is a plan view of an upper half, a bottom view is a lower half, and FIG.

FIGS. 4A, 4B, and 4C are enlarged partial cross-sectional views showing a step of connecting a pin, and FIGS. 4D, 4E, and 4F are enlarged views showing a step of connecting a solder bump; FIGS. It is a partial sectional view.

5A and 5B show a state after wire bonding, in which FIG. 5A is a plan view of an upper half, a bottom view is a lower half, and FIG.

FIGS. 6A and 6B are front cross-sectional views of a mounting structure of a BGA / IC, wherein FIG. 6A shows an embodiment of the present invention and FIG. 6B shows a comparative example.

7A and 7B show a BGA-IC according to another embodiment of the present invention, wherein FIG. 7A is a partially cutaway plan view of an upper half, a bottom view of a lower half, and FIG.

[Explanation of symbols]

11 ... base, 12 ... cavity, 13 ... bonding floor, 14 ... internal terminal, 15 ... pin external terminal, 16 ...
External terminals for bumps, 17: electrical wiring, 18: pins, 18
a: flange portion, 19: silver brazing portion, 20: gold coating, 21: solder bump, 22: solder ball, 23: flux, 24
... assembly, 25 ... bonding layer, 26 ... pellet, 2
7 ... electrode pad, 28 ... wire, 29 ... cap, 30
... hermetically sealed body (sealed body), 31, 31A ... BGA / IC
(Semiconductor device), 40: mounting board, 41: board body, 4
2: Through hole, 43: Land, 44: Soldering part,
45: connection terminal; 46, BGA / IC mounting structure (semiconductor device mounting structure); 47, BGA / IC mounting structure;

Claims (10)

[Claims] An external terminal group is arranged on one main surface of a rectangular flat plate-shaped sealing body in which a semiconductor pellet is sealed,
In a semiconductor device in which solder bumps are provided on each external terminal, a plurality of pins are provided on the one main surface of the sealing body at positions separated from each other. 2. The semiconductor device according to claim 1, wherein a length of said pin is set to be equal to or greater than a height of said solder bump. 3. The device according to claim 1, wherein the plurality of pins are arranged on an outer peripheral portion of one main surface of the sealing body.
Or the semiconductor device according to 2. 4. The semiconductor device according to claim 1, wherein the plurality of pins are arranged at an intermediate portion of one main surface of the sealing body. 5. The semiconductor device according to claim 1, wherein a ground terminal and / or a power supply terminal of the semiconductor pellet is electrically connected to one of the plurality of pins.
5. The semiconductor device according to 3 or 4. 6. An external terminal group is arranged on one main surface of a rectangular flat plate-shaped sealing body in which a semiconductor pellet is sealed,
A method of manufacturing a semiconductor device in which solder bumps are respectively provided on external terminals, the method further comprising a step of projecting a plurality of pins on the one main surface of the sealing body at positions separated from each other. A method for manufacturing a semiconductor device, comprising: 7. The method according to claim 6, wherein the plurality of pins are provided on one main surface of the sealing body before the solder bump group is provided on the external terminal group. The manufacturing method of the semiconductor device described in the above. 8. The semiconductor according to claim 6, wherein the plurality of pins abut against each of the external terminals formed on one main surface of the sealing body and are brazed. Device manufacturing method. 9. The semiconductor device according to claim 1, wherein the plurality of pins and the solder bumps are provided on one main surface of the sealing body before the semiconductor pellet is bonded to the sealing body. 9. The method for manufacturing a semiconductor device according to 6, 7, or 8. 10. The semiconductor device according to claim 6, wherein the plurality of pins and the solder bumps are provided on one main surface of the sealing body after the semiconductor pellet is bonded to the sealing body. 9. The method for manufacturing a semiconductor device according to claim 7, 7 or 8.