JPH11186454A - BGA type integrated circuit component, its manufacturing method and its mounting method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A solder connection portion between a BGA type integrated circuit component such as an IC and a mother board is greatly bulged into a barrel shape to cause a decrease in reliability, or a solder bridge is formed between adjacent connection terminals. To prevent product defects from occurring. SOLUTION: In a BGA type integrated circuit component having a large number of terminal connection solder bumps two-dimensionally arranged on a connection terminal surface of a substrate on which an IC chip is mounted, a high temperature having a melting point higher than that of the solder bumps on a lower surface of the substrate. At least three solder bumps were provided. It is preferable to provide a total of four high-temperature solder bumps near four corners on the lower surface of the substrate. The height of the high-temperature solder bump is preferably higher than that of the terminal connection solder bump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BGA type integrated circuit component, a method of manufacturing the same, and a method of mounting the same.

[0002]

2. Description of the Related Art A BG in which a number of projecting electrodes are two-dimensionally arranged on the lower surface (connection terminal surface) of a substrate on which an IC chip is mounted.
2. Description of the Related Art Integrated circuit components such as A (Ball Grid Array) type ICs and LSIs are known. Here, the protruding electrodes are usually arranged in a lattice shape near the center of the substrate. Usually, solder bumps are used as the protruding electrodes.

FIG. 5 is a view for explaining a conventional solder bump forming process of a BGA type IC and a method of mounting the same on a motherboard. In this figure, reference numeral 10 denotes an IC as a collective circuit component. The IC 10 is obtained by sealing an IC chip 14 mounted on a substrate 12 with a sealing resin 16. The substrate 12 is made of ceramic or glass epoxy resin (glass fiber impregnated with epoxy resin and cured)
Is formed.

On the lower surface of the substrate 12 of the IC 10, that is, on the connection terminal surface, a large number of connection terminal pads 18 arranged in a grid are formed. These connection terminal pads 18
Is formed by removing unnecessary copper foil or a copper plating layer from a copper foil stuck on the lower surface of the substrate 12 or a copper plating layer formed on the lower surface by a method such as photoetching. These connection terminal pads 18 are connected to terminals (not shown) of the IC chip 14 by an inner layer circuit formed on the substrate 12.

[0005] A flux 20 is applied to the lower surface (connection terminal surface) of the substrate 12, and solder balls 22 are supplied one by one onto each connection terminal pad 18 with this surface facing up ((FIG. 5) A)). Here, the flux 20 has a function of temporarily holding the solder ball 22 on the connection terminal pad 18, and at the same time, cleaning the bonding surface of the connection terminal 18 to improve the bonding of the molten solder.

The solder ball 22 used here is formed by forming a fixed amount of general eutectic solder into a spherical shape. The solder balls 22 are supplied by stacking a template having small holes at the positions of the connection terminal pads 18 on the substrate 12 and placing one solder ball 22 in each small hole of the template.

Next, the substrate 12 is heated by an infrared heater 24. When the substrate 12 is heated to the eutectic temperature of the solder, the solder balls 22 melt at once, and the molten solder becomes spherical due to its surface tension. At this time, the position of the molten solder is automatically adjusted to the center of the connection terminal pad 18 by the surface tension between the connection terminal pad 18 and the molten solder (self-alignment action). Therefore, if cooled as it is, a spherical solder, that is, a solder bump 26 is formed on each connection terminal pad 18 (FIG. 5B).

On the other hand, a mother board 28 on which the IC 10 on which the solder bumps 26 are formed is mounted on the mother board 28.
Connection terminal pad 30 corresponding to connection terminal pad 18
Are formed, and cream solder 32 is supplied to these connection terminal pads 30. This cream solder 32
Supplied by screen printing method. Alternatively, a predetermined amount of cream solder 32 may be supplied to each connection terminal in order by a dispenser.

The motherboard 28 includes the IC 10
Are aligned and placed (FIG. 5C). That is, the solder bumps 26 of the IC 10 are placed on the corresponding connection terminal pads 30 of the motherboard 28 while being aligned. When the whole is heated by the infrared heater 34, the solder bumps 26 and the cream solder 32 melt (reflow).
I do. If the whole is cooled as it is, the solder bumps 26 and the cream solder 32 solidify, and the connection terminal pads 18 and 30 are solidified.
(FIG. 5D).

[0010]

As described above, in the conventional method, the IC
The ten solder bumps 26 are placed on the connection terminal pads 30 of the motherboard 28, and all the solder bumps 26 and the cream solder 32 are simultaneously reflowed. Therefore, in this state, the weight of the IC 10 is supported by the surface tension of the molten solder on all the terminals.

However, when the number of connection terminal pads is smaller than the weight of the IC 10 or the area of the connection terminal pads is small and the amount of solder placed thereon is small, the molten solder is pushed by the weight of the IC 10. Crushed. FIG. 6 is a cross-sectional view showing this state. When the molten solder is crushed as described above, the solidified solder connection portion 36A also has a large barrel-shaped diameter. For this reason, the interval between the adjacent solder connection portions 36A becomes small, and the reliability of the circuit, particularly the reliability against thermal expansion and thermal contraction, is reduced (FIG. 6A).

If the weight of the IC 10 and the surface tension of the molten solder are unbalanced, or if there is a large degree of mismatch between the pitch (interval) of the connection terminal pads and the diameter of the solder bumps 26, the adjacent connection terminals may be damaged. Melted solder is joined to each other by surface tension, and the solder bridge 3
8 may be formed. For this reason, a short circuit (short) between the connection terminals occurs, resulting in a product defect.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a solder connection between a BGA type integrated circuit component such as an IC and a motherboard is greatly expanded into a barrel shape, which causes a decrease in reliability. It is a first object of the present invention to provide a BGA type integrated circuit component capable of preventing occurrence of product defects due to occurrence of solder bridges between adjacent connection terminals.

It is a second object of the present invention to provide a method of manufacturing the BGA type integrated circuit component. Furthermore, this BGA
It is a third object to provide a method for mounting a die integrated circuit component on a motherboard.

[0015]

According to the present invention, an object of the present invention is to provide a BGA type integrated circuit component having a large number of terminal connection solder bumps two-dimensionally arranged on connection terminal surfaces of a substrate on which an IC chip is mounted. At least three high-temperature solder bumps having a melting point higher than that of the solder bump projecting from the lower surface of the BGA type integrated circuit component.

Here, three or more high-temperature solder bumps are preferably provided on the lower surface of the substrate as far as possible, and for example, a total of four high-temperature solder bumps are preferably provided near four corners. The height of the high-temperature solder bump is preferably higher than that of the terminal connection solder bump. This is because cream solder is supplied to the terminal pads on the motherboard side, and the solder bumps for connecting the terminals are melted and integrated with the cream solder. Is to be set.

A second object of the present invention is to provide a method of manufacturing a BGA type integrated circuit component having a large number of terminal connection solder bumps two-dimensionally arranged on connection terminal surfaces of a substrate on which an IC chip is mounted. Forming dummy terminal pads together with connection terminal pads in at least three places near the periphery of the connection terminal surface of the substrate; b) supplying high-temperature solder balls to these dummy terminal pads and heating them at a first reflow heating temperature to thereby heat the high-temperature solder. Forming a bump; c) supplying a solder ball for terminal connection to the connection terminal pad, and heating to a reflow heating temperature lower than the first reflow heating temperature in the step b) to form a solder bump for terminal connection. Steps: This is achieved by a method for manufacturing a BGA type integrated circuit component having the above steps.

A third object of the present invention is to provide a mounting method for surface mounting a BGA type integrated circuit component on a motherboard according to claim 1, wherein: a) a solder bump for connecting a terminal of the BGA type integrated circuit component on a component mounting surface of the motherboard; Forming a dummy pad corresponding to a high-temperature solder bump together with a corresponding terminal pad; b) supplying cream solder to the terminal pad formed in the step a); c) connecting terminals of a BGA type integrated circuit component Aligning and mounting the solder bumps and the high-temperature solder bumps on the terminal pads and the dummy pads of the motherboard; d) reheating the terminal connection upper solder bumps by heating to a first reflow heating temperature not higher than the melting temperature of the high-temperature solder bumps. B; comprising each of the above steps
This is achieved by a mounting method of a GA type integrated circuit component.

[0019]

FIG. 1 is a view showing an embodiment of a manufacturing method according to the present invention, FIG. 2 is a view showing an embodiment of the same mounting method, and FIG. 3 is a bottom view of an IC showing an example of arrangement of solder bumps. .

In FIGS. 1 to 3, reference numeral 50 denotes a BGA type IC.
And has a substrate 52, an IC chip 54, and a sealing resin 56. On the lower surface (connection terminal surface) of the substrate 50, a large number of connection terminal pads 58 are densely arranged in a lattice pattern near the center, and one dummy terminal pad 60 is formed at each of the four corners of the lower surface. Have been. The dummy terminal pad 60 is formed in the same step as the connection terminal pad 58. The dummy terminal pad 60 need not be electrically connected to another circuit pattern, and may be formed on the lower surface of the substrate 52 independently of other circuits.

The IC 50 is held with the lower surface of the substrate 52 facing upward, and in this state, the cream solder 62 is supplied to the dummy terminal pads 60 (FIG. 1A). The cream solder 62 used here may be a mixture of fine particles of eutectic solder widely used in a high-viscosity flux, but it is preferable to use fine particles of high-temperature solder.

A high-temperature solder ball 64 is placed on the cream solder 62 supplied to the dummy terminal pad 60 (FIG. 1A). For example, a metal mask having a small hole is placed at the position of the dummy terminal pad 60, and high-temperature solder balls 64 are put into the small holes one by one from above. The high-temperature solder balls 64 are temporarily fixed by the viscosity of the cream solder 62.

In this state, the high-temperature infrared heater 66 is entirely heated.
And the melting temperature of the high-temperature solder ball 64 (first reflow heating temperature T ₁ ). And reflow (Fig. 1
(B)). By this reflow, the high-temperature solder balls 64
The high-temperature solder bump 68 is formed by melting the solder paste 62 and solidifying the two together.

Next, cream solder 70 is supplied to the connection terminal pads 58 (FIG. 1C). The cream solder 70 uses fine grains of eutectic solder, and is connected to the connection terminal pads 58 by, for example, a dispenser (not shown).
A fixed amount of cream solder 70 is placed in order for each time.
Each connection terminal pad 58 on which this cream solder 70 is placed
The solder balls 72 for terminal connection are supplied one by one, and are temporarily fixed by the viscosity of the cream solder 70 itself (FIG. 1C). This solder ball 72 is made of eutectic solder.

Then, the whole is put into a reflow furnace having an infrared heater 74 and heated (FIG. 1D). The temperature (second reflow heating temperature) T ₂ at this time is the solder ball 72.
There is a eutectic temperature of YutakaToru, the high temperature solder balls 64 that is less than the first reflow heating temperatures T ₁ for melting.
By this reflow, the solder ball 72 and the cream solder 70 are melted and integrated, and then solidified to form a solder bump 76 for terminal connection. At this time, the high-temperature solder bump 68 does not melt. FIG. 3 shows the arrangement of the terminal connection solder bumps 76 and the high-temperature solder bumps 68.

The IC 50 having the high-temperature solder bumps 68 and the terminal connection solder bumps 76 formed thereon is mounted on a motherboard 78 as shown in FIG. That is, the terminal pads 8 corresponding to the connection terminal pads 58 and the dummy terminal pads 60 of the IC 50 are provided on the motherboard 78.
0 and dummy terminal pads 82 are formed in advance, and cream solders 84 and 86 are supplied to these pads 80 and 82, respectively (FIG. 2E).

The IC 50 is attached to these pads 80 and 82.
The solder bumps 76 and the high-temperature solder bumps 68 are placed in alignment and placed in a reflow furnace. Infrared heaters 88 in the reflow furnace holds heating reflow furnace to a second reflow temperature T _2. Therefore, in this reflow furnace, only the solder bump 76 and the cream solders 80 and 86 are melted, and the high-temperature solder bump 68 is not melted (FIG. 2 (F)).

Since the high temperature solder bump 68 does not melt,
The gap between the motherboard 78 and the IC 50 is kept constant by hitting the dummy pad 82 of the motherboard 78. That is, the gap size between the connection terminal pads 58 and 80 is kept constant by the height of the high-temperature solder bump 68. As a result, the connection between the terminal pads 58 and 80 bulges in a barrel shape as shown in FIG. 6 (FIG. 6A), or a solder bridge between adjacent pads (FIG. 6B). Will not be generated.

It should be noted in the step shown in (F) in FIG. 2, although the solder bumps 76 have been described as heated to a second reflow heating temperature T ₂ of melting, the solder bumps 76 and 68 only the cream solder 84 is melted The cream solders 84 and 86 alone may be reflowed by heating to a temperature at which they do not melt (third reflow heating temperature) T ₃ (T ₃ <T ₂ <T ₁ ).

Next, a method for determining an appropriate size of the high-temperature solder bump 68 will be described with reference to FIG. FIG. 4 is an enlarged view of the high-temperature solder bump 68 and the terminal-connecting solder bump 76 and comparing their dimensions. The height of the terminal connection solder bump 76 is a, the thickness of the cream solders 84 and 86 is b, and the height of the high-temperature solder bump 68 is c.

The reflow of the cream solders 84 and 86 causes the flux components contained therein to disappear, so that the volume thereof is reduced. Considering this reduction amount and considering that the tip of the terminal connection solder bump 68 is hemispherical, ideal pads 58 and 80 connected by the volume of the terminal connection solder bump 68 and the cream solder 84 are formed. The interval c can be substantially obtained by c = a + (b × 0.5).

Since the tip of the high-temperature solder bump 68 does not melt and the tip of the high-temperature solder bump 68 abuts on the dummy terminal pad 82 of the motherboard 78, setting the height of the high-temperature solder bump 68 to c obtained in this manner allows all connection terminals to be connected. The distance between the pads 58 and 80 can be controlled to this dimension c. Therefore, the shape of the solder connecting all the connection terminal pads 58 and 80 is properly adjusted, and the solder does not become a barrel shape or a bridge.

[0033]

As described above, according to the first aspect of the present invention, at least three high-temperature solder bumps having a higher melting point than the terminal connection solder bumps are provided on the lower surface of the substrate.
BGA type integrated circuit parts (integrated circuit elements, IC, LSI)
The distance between the terminal and the motherboard can be kept constant, and it is possible to prevent the solder terminal portion connecting between the terminals from being excessively expanded in a barrel shape and the occurrence of a solder bridge between adjacent terminals. Therefore, the reliability of the product is improved, and the yield of the product is improved.

It is desirable to provide the high-temperature solder bumps as far as possible from each other on the substrate for the purpose of stabilizing the substrate, and it is most desirable to provide one at each of the four corners of the substrate. In consideration of the fact that the cream solder supplied to the connection terminals of the mother board is integrated with the terminal connection solder bumps, it is desirable that the high-temperature solder bumps be protruded higher than the terminal connection solder bumps. .

According to the fourth aspect of the present invention, a method of manufacturing the BGA type integrated circuit component is obtained. According to the fifth aspect of the present invention, there is provided a method of mounting the BGA type integrated circuit component on a motherboard.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a manufacturing method according to the present invention.

FIG. 2 is a diagram showing an embodiment of the mounting method.

FIG. 3 is a diagram showing an example of an arrangement of solder bumps;

FIG. 4 is an explanatory view of a height of a solder bump.

FIG. 5 shows a conventional method.

FIG. 6 is a diagram illustrating inconvenience caused by a conventional method.

[Explanation of symbols]

 10, 50 BGA type integrated circuit component (IC, LSI) 12, 52 substrate 14, 54 IC chip 16, 56 sealing resin 18, 30, 58, 80 connection terminal pad 28, 78 motherboard 60, 82 dummy terminal pad 62, 70, 84, 86 Cream solder 64 High-temperature solder ball 68 High-temperature solder bump 72 Solder ball for terminal connection 76 Solder bump for terminal connection

Claims (5)

[Claims] 1. A BGA type integrated circuit component having a large number of terminal connection solder bumps two-dimensionally arranged on connection terminal surfaces of a substrate on which an IC chip is mounted, wherein the lower surface of the substrate has a lower melting point than the solder bumps. BGA type integrated circuit component characterized in that at least three high temperature solder bumps having a high height are projected. 2. The BGA according to claim 1, wherein each of the high-temperature solder bumps protrudes one at a time near each of four corners on the lower surface of the substrate.
Type integrated circuit parts. 3. The BG according to claim 1, wherein the high-temperature solder bump protrudes higher than the terminal connection solder bump.
A-type integrated circuit components. 4. A method of manufacturing a BGA type integrated circuit component having a large number of terminal connection solder bumps two-dimensionally arranged on a connection terminal surface of a substrate on which an IC chip is mounted, comprising: a) a connection terminal surface of the substrate; Forming dummy terminal pads together with connection terminal pads in at least three places near the periphery of the semiconductor device; b) forming high-temperature solder bumps by supplying high-temperature solder balls to these dummy terminal pads and heating them to a first reflow heating temperature; C) supplying a solder ball for terminal connection to the connection terminal pad, and heating to a second reflow heating temperature lower than the first reflow heating temperature in the step b) to form a solder bump for terminal connection. A method of manufacturing a BGA-type integrated circuit component, comprising the above steps. 5. A mounting method for surface mounting a BGA type integrated circuit component on a motherboard according to claim 1, wherein: a) a terminal pad corresponding to a solder bump for connecting a terminal of the BGA type integrated circuit component on a component mounting surface of the motherboard. Forming a dummy terminal pad corresponding to the high-temperature solder bump; b) supplying cream solder to the terminal pad formed in the step a); c) solder bump for terminal connection of the BGA type integrated circuit component and high temperature Aligning and mounting the solder bumps on the terminal pads and the dummy terminal pads on the motherboard; d) reheating the terminal connection solder bumps by heating to a first reflow heating temperature equal to or lower than a melting temperature of the high-temperature solder bumps; B comprising the above steps
A mounting method for GA type integrated circuit components.