JP4521494B2 - BGA type semiconductor package mounting structure and reinforcing resin filling method - Google Patents

Description

  The present invention has a structure in which a BGA (Ball Grid Array) type semiconductor package having a plurality of electrodes arranged in a matrix on the bottom surface is mounted on a printed wiring board, and in particular, a lower surface of the BGA type semiconductor package and an upper surface of the printed wiring board. And a gap between the bottom surface of the BGA type semiconductor package and the top surface of the printed wiring board, and a gap between the bottom surface of the BGA type semiconductor package and the top surface of the printed wiring board. The present invention relates to a method of filling a reinforcing resin.

Since the BGA type semiconductor package is a mounting structure that is fixed to the printed wiring board only by the solder balls attached to the respective electrode portions on the bottom surface thereof, it is vulnerable to external impacts. For example, when a strong impact due to dropping or the like is applied to a portable electronic device in which this is incorporated, the soldering part is peeled off or a crack is generated in the soldering part, and the BGA type semiconductor package is dropped from the printed wiring board. The electrical connection between the semiconductor package and the printed wiring board becomes defective and cannot be used.
Therefore, when mounting the BGA type semiconductor package, it is important to prevent the BGA type semiconductor package from dropping off the printed wiring board or causing poor connection due to external impact. At the same time, it is also important that the BGA type semiconductor package can be easily removed when a defect of the BGA type semiconductor package is found.

  As a technique that satisfies such a demand, Patent Document 1 discloses a configuration in which a reinforcing resin is interposed only in a part of the gap between a BGA type semiconductor package and a substrate (printed wiring board) on which the semiconductor package is mounted. Has been proposed. As the first embodiment, if the reference numerals in the drawings are also written, after the BGA type semiconductor package 1 is mounted on the mounting substrate 2, the BGA type semiconductor package 1 and the mounting substrate 2 are used from outside the BGA type semiconductor package 1 and the mounting substrate 2 by using a dispenser. A configuration is described in which a certain amount of reinforcing resin 4 is injected into each corner portion in the gap between the semiconductor package 1 and the mounting substrate 2 (see paragraph [0042] of Patent Document 1).

In Patent Document 2, a frame-shaped reinforcing frame having a side surface surrounding the side surface of the BGA type IC package is attached to a motherboard (printed wiring board) on which the BGA type IC package is mounted. A configuration in which a resin for reinforcing an IC package is filled has been proposed. As the first embodiment, if the reference numerals in the drawings are also written, the nozzle 51 of the dispenser is inserted into the notch 11a formed on the side surface of the reinforcing frame 10 and directly into the gap between the BGA type IC package 1 and the mother board 6. A configuration is described in which the reinforcing resin 50 is injected, and the nozzles 51 of the dispenser are inserted into the notches 12a formed at the four corners of the upper surface of the reinforcing frame 10 to inject the reinforcing resin 50 near the four corners of the BGA type IC package 1. (See paragraphs [0050] to [0055] of Patent Document 2 and FIGS. 2 and 3).
JP 2000-299356 A JP 2000-151083 A

  However, as in Patent Document 1 and Patent Document 2, in the method of directly filling the reinforcing resin in the gap between the BGA type semiconductor package (BGA type IC package) and the printed wiring board (mounting board, motherboard), the nozzle of the dispenser There is a disadvantage in that it is necessary to perform the positioning of the lens with high accuracy and to use an expensive dispenser.

  Although not specified in Patent Document 2, the dispenser nozzles 51 are inserted into the notches 12 a formed at the four corners of the upper surface of the reinforcing frame 10, and the reinforcing resin 50 is injected near the four corners of the BGA type IC package 1. In this case, the reinforcing resin 50 can permeate into the gap between the BGA type IC package 1 and the mother board 6, so that the reinforcing resin 50 is filled into the gap between the BGA type IC package 1 and the mother board 6 by using this method. A way to do this is also conceivable.

However, in this method, the reinforcing resin 50 injected on the upper surface of the mother board 6 near the BGA IC package 1 penetrates between the lower surface of the BGA IC package 1 and the upper surface of the mother board 6 by natural diffusion. Therefore, the permeation region varies depending on the viscosity (fluidity) of the reinforcing resin 50.
The viscosity (fluidity) of the reinforcing resin is easily affected by temperature, so unless the temperature control of the production line is controlled with high accuracy, even if the characteristics of the reinforcing resin itself are the same, what time is the season? There is an inconvenience that the strength quality cannot be kept constant due to an error in the penetration degree of the reinforcing resin depending on where the production base is located (where the production line is located).
Further, the penetration degree of the reinforcing resin varies depending on the time from the injection of the reinforcing resin to the heat treatment for curing the reinforcing resin.

The problem of the present invention is that the bottom surface of the BGA type semiconductor package can be obtained even when the environmental temperature at the time of mounting the BGA type semiconductor package on the printed wiring board is greatly different, that is, even when the manufacturing time (season) or manufacturing base is different. It is possible to make the penetration degree of the reinforcing resin filled in the gap between the PCB and the upper surface of the printed circuit board substantially the same, the filling range of the reinforcing resin becomes substantially constant, and the strength quality can be made substantially constant. It is to provide a mounting structure.
Further, the problem of the present invention is that when mounting a BGA type semiconductor package on a printed wiring board, even if the environmental temperature is greatly different, that is, even if the manufacturing time (season) or manufacturing base is different, a simple method is used. Provided a method of filling a reinforcing resin that can make the penetration degree of the reinforcing resin into the gap between the lower surface of the BGA type semiconductor package and the upper surface of the printed wiring board substantially the same, and can make the strength quality constant. It is to be.

In order to solve the above-described problems, the invention described in claim 1 includes mounting a BGA type semiconductor package on a printed wiring board, and reinforcing resin in a gap between the lower surface of the BGA type semiconductor package and the upper surface of the printed wiring board. A BGA type semiconductor package mounting structure with an intervening wall, for example, as shown in FIGS. 1, 3, and 4, a wall surrounding at least a corner of the BGA type semiconductor package 1 on a printed wiring board 11 Between the member 22 and the inner wall surface of the wall member 22 and the side surface of the BGA type semiconductor package 1, a plurality of protrusions 13 protruding along at least the corners of the BGA type semiconductor package 1 are provided and reinforced. The resin for resin diffuses from between the wall member serving as a supply point of the resin and the plurality of protrusions and spreads into the gap.

According to the first aspect of the present invention, on the printed wiring board, the wall member that surrounds at least the corner of the BGA type semiconductor package, and between the inner wall surface of the wall member and the side surface of the BGA type semiconductor package , A plurality of protrusions protruding along at least corners of the semiconductor package, and the reinforcing resin interposed in the gap between the lower surface of the BGA semiconductor package and the upper surface of the printed wiring board includes the wall member and the protrusion Since the reinforcing resin supplied to the gap diffuses and spreads into the gap, the plurality of protrusions protruding along the corners of the BGA type semiconductor package are the reinforcing resin at the time of diffusion. The diffusion range of the reinforcing resin varies depending on the arrangement interval (and the number) of the protrusions.
Therefore, by changing the interval (and the number) of the protrusions in the direction along the side surface of the BGA type semiconductor package, it is possible to control the penetration rate of the reinforcing resin into the gap between the printed wiring board and the BGA type semiconductor package. Become.
For this reason, there are temperature differences between seasons, temperature differences between manufacturing bases when there are multiple manufacturing bases, and differences in production line length from the injection part of the reinforcing resin to the heat treatment part (from the injection of the reinforcing resin to the heat treatment). Regardless of the time difference between the steps, the penetration of the reinforcing resin into the gap between the printed wiring board and the BGA type semiconductor package can be made substantially the same. As a result, the BGA mounted on the printed wiring board The strength quality of the type semiconductor package can be made constant.

The invention according to claim 2 is a method of filling a reinforcing resin in the gap between the lower surface of the BGA type semiconductor package mounted on the printed wiring board and the upper surface of the printed wiring board. as shown, on the printed wiring board 11, a wall member 22 surrounding at least a corner portion of the BGA type semiconductor package 1, between the inner wall and the side surface of the BGA type semiconductor package 1 of the wall member 22, the BGA type A plurality of protrusions 13 projecting along at least the corners of the semiconductor package 1 are provided, and the reinforcing resin 32 is supplied onto the printed wiring board between the inner wall surface of the wall member 22 and the plurality of protrusions 13. The reinforcing resin is filled in the gaps between the plurality of protrusions by diffusion of the reinforcing resin.

According to the second aspect of the present invention, on the printed wiring board, the wall member that surrounds at least the corner of the BGA type semiconductor package, and between the inner wall surface of the wall member and the side surface of the BGA type semiconductor package , A plurality of protrusions projecting along at least the corners of the BGA type semiconductor package, and the BGA type between the plurality of protrusions projecting along the corners of the BGA type semiconductor package and the wall member Since the reinforcing resin that fills the gap between the lower surface of the semiconductor package and the upper surface of the printed wiring board is supplied, the protrusions become resistant to the flow of the reinforcing resin. Therefore, the penetration rate of the reinforcing resin into the gap between the printed wiring board and the BGA type semiconductor package can be controlled by changing the interval (and the number) of the protrusions in the direction along the side surface of the BGA type semiconductor package. it can.
For this reason, there are temperature differences between seasons, temperature differences between manufacturing bases when there are multiple manufacturing bases, and differences in production line length from the injection part of the reinforcing resin to the heat treatment part (from the injection of the reinforcing resin to the heat treatment). The strength of the BGA type semiconductor package mounted on the printed circuit board can be improved by making the penetration degree of the reinforcing resin into the gap between the printed circuit board and the BGA type semiconductor package substantially the same regardless of the time difference) It can be made constant.

  A third aspect of the present invention is a method of filling a reinforcing resin for a BGA type semiconductor package according to the second aspect of the present invention, for example, as shown in FIG. 1, FIG. 3, FIG. 4, FIG. The plurality of protrusions 13 are arranged along the side surface of the BGA type semiconductor package 1 from the corners of the BGA type semiconductor package.

  The invention described in claim 4 is a method of filling a resin for reinforcing a BGA type semiconductor package according to claim 3, wherein the number of protrusions arranged along the side surface of the BGA type semiconductor package 1 and the arrangement interval thereof are: It is characterized by being set according to the temperature.

According to the present invention, on the printed wiring board, at least the BGA type semiconductor package between the wall member surrounding at least the corner of the BGA type semiconductor package and the inner wall surface of the wall member and the side surface of the BGA type semiconductor package. With a simple structure of providing a plurality of protrusions protruding along the corners, and filling the reinforcing resin from between the plurality of protrusions protruding along the corners of the BGA type semiconductor package and the wall member The penetration rate of the reinforcing resin into the gap between the printed wiring board and the BGA type semiconductor package is controlled by changing the distance and number of protrusions along the side surface of the BGA type semiconductor package by a simple method. it can.
Therefore, the temperature difference between seasons, the temperature difference between each manufacturing base when there are multiple manufacturing bases, the difference in the production line length from the injection portion of the reinforcing resin to the heat treatment portion (from the injection of the reinforcing resin to the heat treatment) Regardless of the time difference), the penetration degree of the reinforcing resin into the gap between the printed wiring board and the BGA type semiconductor package can be made substantially the same. As a result, the BGA type semiconductor mounted on the printed wiring board There is an advantage that the strength and quality of the package can be made constant.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
1 to 5 show a configuration of an embodiment to which the present invention is applied. In the figure, 1 is a BGA type semiconductor package, 11 is a printed wiring board, and 21 is a BGA mounted on the printed wiring board 11. 2 is a box-shaped frame that covers the semiconductor package 1.

  The BGA type semiconductor package 1 has a plurality of electrodes arranged in a matrix on the lower surface of the substrate 3 on which the semiconductor chip 2 is mounted on the upper surface. As shown in FIG. A ball 4 is attached. The substrate 3 is covered with a mold resin 5 including a semiconductor chip 2 and an unillustrated bonding pad for connecting the unillustrated electrode pad and the unillustrated electrode pad of the substrate 2.

The printed wiring board 11 has a plurality of electrodes corresponding to the electrodes of the BGA type semiconductor package 1 and, as shown in FIG. 1, positioning holes into which the leg portions 23 provided at the four corners of the frame 21 are inserted and locked. 12.
The frame 21 is made of sheet metal, and as shown in FIG. 1, leg portions 23 projecting downward are formed at both ends of a side wall portion (wall member) 22 that surrounds the four sides of the side surface of the BGA type semiconductor package 1. In addition, a notch 24 is formed in which the lower part of the middle part is opened, and a notch 26 is formed at the four corners of the top plate part 25 that covers the upper surface of the BGA type semiconductor package 1.
The cutout 24 on the side wall of the frame 21 is provided to facilitate the convection of air as a heat dissipation measure for heat generated in the BGA type semiconductor package 1, but noise from the BGA type semiconductor package 1 is provided. In order to prevent radiation or to protect the BGA type semiconductor package 1 from radiation noise from other electronic components, it is better not to have the notch 24 on the side wall portion of the frame 21, and the top plate portion of the frame 21. The smaller notch 26 should be smaller.

Next, mounting of the BGA type semiconductor package 1 on the printed wiring board 11 will be described.
First, the BGA type semiconductor package 1 in which solder balls are attached to the respective electrode portions on the bottom surface is mounted at a predetermined position on the printed wiring board 11, and then the solder on the bottom portion of the BGA type semiconductor package 1 is subjected to a known reflow process. The ball 4 is welded and connected to the electrode on the printed wiring board 11.

After the BGA type semiconductor package 1 is soldered to the printed wiring board 11 in this way and before the frame 21 is attached, the protrusions 13 are formed on the printed wiring board 11 near the corners (four corners) of the BGA type semiconductor package 1.
The protrusion 13 is formed on the printed wiring board 11 by applying (dropping) an adhesive with a dispenser different from a dispenser for applying a reinforcing resin 32 described later.

That is, an adhesive is applied (dropped) with a dispenser (not shown) on the printed circuit board 11 so as to correspond to the four corners of the BGA type semiconductor package 1, thereby along the side surface of the BGA type semiconductor package 1. A plurality of protrusions 13 are formed.
As shown in FIGS. 3 and 4, the protrusions 13 are formed at equal intervals along the side surface of the BGA type semiconductor package 1.

Next, reinforcement of the BGA type semiconductor package 1 will be described.
First, a frame 21 is further mounted on the printed wiring board 11 on which the BGA type semiconductor package 1 is mounted. In the illustrated example, the leg portion 23 of the frame 21 is inserted and locked in the positioning hole 12 of the printed wiring board 11, and the leg portion 23 is soldered to the positioning hole 12. As a result, the frame 21 is fixed on the printed wiring board 11.

After mounting the frame 21 on the printed wiring board 11 in this way, as shown in FIG. 2, the nozzles 31 of the dispenser are inserted from the notches 26 formed at the four corners of the top plate portion of the frame 21, and the inner wall surface of the side wall portion 22 is inserted. The reinforcing resin 32 is injected from between the protrusions 13 (see the resin application (dropping) point P in FIGS. 3 and 4). The reinforcing resin 32 is a thermosetting resin.
The injected reinforcing resin 32 is regulated by the inner wall surface of the side wall portion 22 on the printed wiring board 11 and flows toward the protruding portion 13, and the protruding portion 13 becomes a resistance against the flow of the reinforcing resin 32. The resistance at the projections 13 is applied, and the reinforcing resin 32 flows into the gaps between the projections 13 and also flows over the projections 13 to the corners of the BGA type semiconductor package 1.

Then, the reinforcing resin 32 flows into the gap between the printed wiring board 11 and the corner of the BGA type semiconductor package 1 as shown by arrows in FIGS. 3 and 4, and as shown in FIG. It penetrates and fills the periphery of the solder balls 4 at the bottom of the package 1.
Thereafter, heat treatment is performed to cure the reinforcing resin 32. As a result, the lower surface of the BGA type semiconductor package 1 is bonded to the printed wiring board 11 by the reinforcing resin 32 filled around the solder balls 4, and the side surface remains on the printed wiring board 11. Since the reinforcing resin 32 is adhered to the printed wiring board 11 and the side wall portion 22 of the frame 21, the reinforcing resin 32 is fixed to the printed wiring board 11 with sufficient strength to withstand external impacts.

The penetration speed of the reinforcing resin 32 into the gap between the printed wiring board 11 and the BGA type semiconductor package 1 is as shown in FIG. 3 when the interval between the protrusions 13 is reduced (the number is increased), As shown in FIG. 4, unlike the case where the interval between the protrusions 13 is increased (the number is reduced), the case where the interval is increased is faster. That is, the penetration speed of the reinforcing resin 32 into the gap between the printed wiring board 11 and the BGA type semiconductor package 1 is controlled by changing the interval and the number of protrusions 13 along the side surface of the BGA type semiconductor package 1. it can.
Therefore, by appropriately setting the interval and the number of protrusions 13 in the direction along the side surface of the BGA type semiconductor package 1 according to the season and the manufacturing base, Regardless of the temperature difference between the manufacturing bases, the difference in production line length from the injection part of the reinforcing resin to the heat treatment part (the time difference from the injection of the reinforcing resin to the heat treatment), etc., the printed wiring board 11 and the BGA The penetration degree of the reinforcing resin 32 into the gap with the type semiconductor package 1 can be made substantially the same, and the strength quality of the BGA type semiconductor package 1 mounted on the printed wiring board 11 can be made constant.

In the above embodiment, the frame 21 is attached after the projection 13 is formed. However, when the notch 26 in the top plate portion of the frame 21 is extended to the entire area where the projection 13 is formed, the frame 21 Even after 21 is attached, the protrusion 13 can be formed.
The soldering of the frame 21 to the printed wiring board 11 is performed after the BGA type semiconductor package 1 is soldered to the printed wiring board 11. However, the soldering of the frame 21 to the printed wiring board 11 is cream solder. Etc., the soldering of the frame 21 to the printed wiring board 11 and the soldering of the BGA type semiconductor package 1 to the printed wiring board 11 can be simultaneously performed by a single reflow process. In this case, the reinforcing resin 32 in the present embodiment is a thermosetting resin as described above, and the heat during the reflow process when the BGA type semiconductor package 1 and the frame 21 are soldered to the printed wiring board 11 is used. Since it can be hardened, the reinforcing resin is applied (dropped) along the side surface of the BGA type semiconductor package 1 at a predetermined interval using a dispenser for applying the reinforcing resin 32 before performing the reflow process. Thus, the protrusion 13 can be formed of the same resin as the reinforcing resin 32.

[Modification]
FIG. 6 shows a modified example of the interval at which the protrusion 13 is provided. That is, as shown in the figure, the distance between the protrusions 13 is increased as the distance from the resin application (dropping) point P increases.

  FIG. 7 shows a modified example in which the protrusion 14 is provided to prevent the reinforcing resin 32 from flowing more than necessary along the side wall portion 22 of the frame 21. That is, as shown in the drawing, a plurality of protrusions 14 for stopping the flow of the reinforcing resin 32 are provided between the protrusions 13 at both ends in the direction along the side surface of the BGA type semiconductor package 1 and the side walls 22. Is.

[Modification of frame]
FIG. 8 shows a modified example of the frame 21. That is, the frame 21 is composed of side wall portions 22 surrounding the four peripheral sides of the side surface of the BGA type semiconductor package 1 as shown in the figure, and the upper surface is opened. The side wall portion 22 is formed with leg portions 23 projecting downward at both end portions, and is formed with side cutouts 24 that open the upper portion of the intermediate portion.

In the present invention, the main purpose of the frame of the embodiment is to prevent the reinforcing resin from flowing out onto the printed circuit board, and therefore it is not necessary to be a frame. If the reinforcing resin is permeated from the four corners of the BGA type semiconductor package, four wall members (partitions) may be provided independently at the four corners of the BGA type semiconductor package. The frame and wall member (screen) need not be metal.
Further, the number and shape of the protrusions are arbitrary, and it is needless to say that other specific detailed structures can be appropriately changed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view showing a configuration of an embodiment to which the present invention is applied and showing a state before a frame is put on a printed wiring board on which a BGA type semiconductor package is mounted. It is a perspective view which shows the state explaining filling of the resin for reinforcement after covering a flame | frame. It is a principal part top view explaining the penetration | invasion state of resin for reinforcement. It is a principal part top view explaining the osmosis | permeation state of the reinforcing resin when the space | interval of a projection part is wide. It is the longitudinal cross-sectional view which showed the mounting state after resin filling for reinforcement. It is a principal part top view which shows the modification which enlarged the space | interval which provides a projection part, so that it leaves | separates from the resin application point for reinforcement. It is a principal part top view which shows the modification which provided the projection part for preventing the resin for reinforcement to flow more than necessary along a flame | frame (wall member). It is the disassembled perspective view which showed the modification of the flame | frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 BGA type semiconductor package 2 Semiconductor chip 3 Board | substrate 4 Solder ball 5 Mold resin 11 Printed wiring board 13 Protrusion part 21 Frame 22 Side wall part (wall member)
32 Resin for reinforcement

Claims (4)

A BGA type semiconductor package mounting structure in which a BGA type semiconductor package is mounted on a printed wiring board, and a reinforcing resin is interposed in a gap between the lower surface of the BGA type semiconductor package and the upper surface of the printed wiring board,
On the printed wiring board, a wall member surrounding at least a corner of the BGA type semiconductor package;
Between the inner wall surface of the wall member and the side surface of the BGA type semiconductor package, there are provided a plurality of protrusions protruding along at least corners of the BGA type semiconductor package ,
The BGA type semiconductor package mounting structure, wherein the reinforcing resin diffuses from between the wall member serving as a supply point of the resin and the plurality of protrusions and spreads into the gap. A method of filling a reinforcing resin in a gap between a lower surface of a BGA type semiconductor package mounted on a printed wiring board and an upper surface of the printed wiring board,
A wall member surrounding at least a corner of the BGA type semiconductor package on the printed wiring board;
Between the inner wall surface of the wall member and the side surface of the BGA type semiconductor package, a plurality of protrusions protruding along at least corners of the BGA type semiconductor package are provided.
The reinforcing resin is supplied onto the printed wiring board between the inner wall surface of the wall member and the plurality of protrusions, and the reinforcing resin is diffused between the plurality of protrusions by diffusion of the reinforcing resin. A reinforcing resin filling method for a BGA type semiconductor package, characterized in that the gap is filled.   3. The method of filling a reinforcing resin for a BGA type semiconductor package according to claim 2, wherein the plurality of projecting portions are arranged along a side surface of the BGA type semiconductor package from a corner portion of the BGA type semiconductor package.   4. The method for filling a reinforcing resin in a BGA type semiconductor package according to claim 3, wherein the number of protrusions arranged along the side surface of the BGA type semiconductor package and the arrangement interval thereof are set according to temperature.

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