JP4158158B2 - Solder ball container - Google Patents

Description

  The present invention relates to a container filled with solder balls.

  When an area array type multifunctional electronic component such as BGA / CSP is mounted on a printed circuit board, solder bumps are formed by previously soldering the terminals arranged in a lattice pattern on the package surface. Thereafter, the multifunctional electronic component is placed on the printed board and reflowed, and similarly, solder connection is made between the lands arranged in a grid pattern on the printed board. Solder balls are used to form the solder bumps.

  The spacing between these grid-like terminals is usually a very narrow pitch of several hundred microns, and the terminals are similarly fine in size, so that no bridging between terminals, poor conduction, etc., occur between the terminals and the solder. High connection reliability with the ball is required.

  When forming solder bumps, the solder balls may not adhere to the terminals completely, resulting in poor conduction, or dirt may adhere around the solder bumps, resulting in failure. If a soldering failure occurs even once, such an area array type multifunctional electronic component is difficult to regenerate, so that a very expensive multifunctional electronic component becomes defective.

  One factor that causes soldering failure is the blackening of the solder ball surface. When the surface of the solder ball is covered with black powder and blackened, the black powder inhibits adhesion between the molten solder and the terminal when the solder ball is melted, resulting in insufficient adhesive strength. Insufficient adhesion strength itself causes poor conduction, and also causes disconnection when a solder ball receives a strong impact or undergoes repeated stress due to thermal expansion. Even if the solder ball and the terminal are in close contact with each other, when the solder ball is melted, the black powder floating on the surface aggregates and remains in the vicinity of the solder ball, resulting in contamination.

  When the solder balls are filled in a solder ball container (hereinafter referred to as a container) and transported, the solder balls are blackened due to the vibration of the solder balls or the solder balls rubbing against the inner wall of the container. This is remarkable particularly when the volume of the solder balls to be filled is small and the gap is large with respect to the internal volume of the container. Therefore, in order to prevent blackening, it is important to minimize the gap formed when the solder ball is filled in the container.

  By the way, the conventional container is comprised from the container main body 1, the outer cover 2, and the inner cover 3 as shown in FIG. The container body is usually a bottomed cylinder, has an opening at the top, and is provided with a male screw on the outside of the top. In addition, a tapered seal portion 4 is provided on the inner wall portion of the container body to press and seal the outer peripheral portion of the inner lid tip.

  The inner lid 3 has a bottomed cylindrical shape, and a flange 6 is formed on the top. The outer lid 2 has a cap shape, and has an inner wall provided with a female screw that is screwed with a male screw of the container body. After filling the solder ball 5 into the container body 1, the inner lid 3 is inserted into the opening of the container body 1, and further the outer lid 2 is put on and screwed, whereby the flange portion 6 of the inner lid 3 is pressed by the outer lid 2. As a result, a load for sealing is applied to the seal portion 4, and the inside of the container is sealed.

  Here, when the solder ball is filled in the container, the volume of the solder ball greatly varies depending on the particle size and quantity of the solder ball. Since the conventional container has a constant internal volume, if it is intended to fill this container with solder balls of various particle sizes and quantities, it is better to increase the internal capacity of the container before designing the container. It is economical without increasing the types of containers. However, on the other hand, when this container is filled with a small amount of solder balls having a small particle diameter, the volume of the solder balls becomes smaller than the inner volume of the container, and a large gap 7 is formed inside the container.

As described above, when the solder balls filled in a container having a large gap are transported, the solder balls or the solder balls are rubbed against the inner wall of the container due to vibration during transportation. As a method for preventing blackening of the surface of the solder ball due to vibration during transportation, there is a solder ball container that can be separated from the inner lid and the projecting length of the projecting body can be adjusted (see Patent Document 1).
JP 2000-335633 A

  The solder ball container shown in Patent Document 1 described above is a container having a feature that, when the solder ball is filled in the container and the protrusion is immersed in the solder ball layer, the solder ball is spread and the gap can be reduced. is there. This is excellent in that the gap can be freely adjusted even if the volume of the solder balls filled in the container changes.

  However, in this method, if the solder ball is extremely pressed when the protruding body spreads the solder ball, there is a concern about the deformation of the solder ball. When such deformed solder balls are mixed in normal solder balls, there is a problem that the mounting rate when mounting the solder balls on the terminals of the multifunctional electronic component is lowered, and the productivity is deteriorated.

  An object of the present invention is to provide a solder ball container that can reduce the blackening of the surface of the solder ball due to rubbing during transportation and can reduce deformation of the solder ball.

The present invention has been made in view of the above-described problems. That is, the present invention provides a solder ball container in which the outer peripheral end of the inner lid is pressed against a seal part formed on an inner wall part of a bottomed cylindrical container body, and the seal part is an opening of the container body. This is a solder ball container having a taper shape in which the inner diameter gradually decreases from the portion toward the bottom, and is provided at two or more locations.

  According to the solder ball container of the present invention, the gap is adjusted stepwise by selecting the one with the smallest gap from two or more types of inner lids having different dimensions according to the number of solder balls filled in the container body. This is possible, and the blackening of the solder balls can be prevented. Further, the solder ball is not deformed, and it is possible to obtain effects such as improving the mounting property of the solder ball on the multifunctional electronic component and improving the productivity.

  The solder ball container according to the present invention includes a bottomed cylindrical container body 1 and an inner lid 3a as shown in FIG. An important feature of the present invention is that, as shown in FIG. 1 (1), a seal different from the seal portion 4a for sealing the inner lid 3a against the inner wall portion of the bottomed cylindrical container body 1 is sealed. That is, the portions 4b and 4c are provided in a total of three locations from the opening of the container body 1 toward the bottom. Here, the seal portion refers to a sealed portion formed by pressing the inner wall surface of the container main body and the outer peripheral end of the inner lid in order to prevent the outside air from entering the container. In the case of FIG. 1 (1), the seal part has a function by providing a step on the inner wall surface of the container body.

  In the case of the container shown in FIG. 1 provided with a plurality of seal portions 4a, 4b, 4c, three types of inner lids 3a, 3b, 3c corresponding to these three seal portions are prepared. And these usage forms are as having shown to FIG. 1 (1)-(3), and when sealing a container with the 1st seal | sticker part 4a, the 1st inner lid 3a is opening of the container main body 1. FIG. Insert into the part. Similarly, when sealing with the second seal portion 4b or the third seal portion 4c, the second inner lid 3b or the third inner lid 3c is inserted into the opening of the container body 1.

  The first seal portion 4a is at a position closest to the opening of the container body among the three seal portions, and forms the largest internal volume when sealed by the seal portion 4a. Therefore, when the volume of the solder ball 5 filled in the container is larger than the inner volume when sealed by the second seal portion 4b, the first inner lid 3a is attached as shown in FIG. And sealing at the position of the first seal portion 4a.

  On the other hand, the volume of the solder ball 5 filled in the container is smaller than the inner volume when sealed by the second seal portion 4b, but larger than the inner volume when sealed by the third seal portion 4c. In this case, the inner lid 3b is used to seal with the seal portion 4b. And when the volume of the solder ball 5 with which the container is filled is equal to or smaller than the inner volume when sealed by the third seal portion 4c, the seal portion 4c is sealed using the third inner lid 3c. . Thus, the volume of the gap can be reduced by appropriately selecting the inner lid according to the volume of the solder balls filled in the container.

  When the solder ball is filled and sealed using a predetermined seal portion, the volume of the gap 7 formed is suitably 10% or less with respect to the inner volume of the container formed by the seal portion. If it is more, blackening of the solder ball surface tends to occur due to vibration during transportation. Accordingly, if many seal portions are provided, the volume of the gap 7 can be reduced corresponding to the particle size and quantity of all solder balls, but it is necessary to prepare a variety of corresponding inner lids. About 3 to 5 locations are appropriate. In the solder ball container shown in FIGS. 1 (1) to 1 (3) shown as an example of the present invention, the container body 1 is provided with three seal portions. In this case, the inner volume of the container can be adjusted in three stages according to the volume of the solder balls to be filled.

  Further, when designing the container, the positions of the plurality of seal portions provided from the opening of the container main body toward the bottom may be provided so that the internal volume of the entire container is equally divided by the number of seal portions. If another small container can be prepared, the value of the total internal volume of the small container should be divided equally between the value of the internal volume of the container to be designed by the number of seals. For example, the volume of the gap can be further reduced, and the quantity of various solder balls can be finely accommodated.

  When the container body is longitudinally cut from the opening toward the bottom, the cross-sectional shape of the seal portion provided using a step on the inner wall of the container body is as shown in FIG. 1 from the opening toward the bottom. It is preferable that the inner diameter is tapered for a while. And as for the front-end | tip outer periphery part of the inner cover which will contact | connect the seal | sticker part, it is preferable that the edge becomes R shape. When the inner lid is inserted into the container body opening, the R shape of the outer periphery of the tip of the inner lid stops in contact with the corresponding seal portion. At that time, the flange 6 of the inner lid is against the upper edge of the opening of the container body. The length and outer diameter of the inner lid are adjusted so as to stop with some floating. Then, when an outer lid that is prepared separately or may be formed integrally with the inner lid is screwed into the male screw at the upper part of the container body, the flange 6 of the inner lid is pressed by the outer lid, and the taper shape of the seal portion A load is applied to the circumferential contact surface between the portion and the R-shaped portion of the outer peripheral end of the inner lid, and the outer peripheral end of the inner lid is pressed against the seal portion, so that the inside of the container is tightly sealed. .

  If the taper angle of the seal portion provided on the inner wall surface of the container main body is a range of 5 to 45 ° with respect to the peripheral surface (load) direction of the inner lid that is a bottomed cylinder, the above It is preferable in that the sealing action is obtained. When the taper angle exceeds 45 °, the solder ball tends to stay in the tapered portion. If the inner lid is inserted while leaving the staying solder balls, the solder balls are crushed and deformed. If a deformed solder ball is mixed with a normal solder ball, when mounting the solder ball on the terminal of a multi-function electronic component, more than the required number of solder balls adhere to the mounting jig, Or it may not be installed. Further, when the deformed solder ball is caught in the mounting jig, it is necessary to stop the production and clean the mounting jig or the like, which significantly deteriorates the productivity.

  The solder ball container shown in FIG. 1 shown as an example further assists the sealing and sealing action by the inner lid by using an independent outer lid, and seals the container. The solder ball container of the present invention that uses the sealing function by the inner lid as the basis of the operation and effect does not require the presence of the outer lid, but naturally does not prevent the use of the outer lid. And as described above, even if the inner lid is integrated with the outer lid, the outer periphery of the tip, which is a part that functions as the function of the inner lid, is pressed against the seal portion on the container body side. Needless to say, any shape that achieves sealing is included in the solder ball container of the present invention.

  As described above, in the solder ball container of the present invention, the outer dimensions of the container itself are constant regardless of the number of solder balls filled in the container. Therefore, in addition to the effect of preventing solder ball blackening, when packaging a plurality of solder ball containers in a single outer box for transportation, etc., the outer box and partitions placed in the outer box can be It is not necessary to prepare several types depending on the size, and as a result, it is possible to reduce the packing cost and the storage space such as the outer box and the partition.

The present invention will be described in more detail based on the containers shown in FIGS.
The containers shown in FIGS. 1 (1) to 1 (3) are provided with three seal portions for pressing and sealing the inner lid on the inner wall portion of the container main body 1. Depending on the volume of the solder balls filled in the container, the inner lid having a size corresponding to the sealing position is selected so as to seal at the position where the gap is the smallest. When the inner lid is inserted into the container, the outer periphery of the tip of the inner lid comes into contact with the seal provided on the inner wall of the container body, and the outer lid is screwed into the male screw at the upper part of the container body, so that the flange at the upper portion of the inner lid The structure is such that a load for sealing is applied to the seal portion by being pressed down by the outer lid.

A solder ball blackening test was conducted using the container of the present invention and a conventional container. The container of the present invention has an inner volume of 40,000 mm ³ when the first inner lid 3a is attached and sealed with the first seal portion 4a. The inner volume when the second inner lid 3b is attached and sealed with the second seal portion 4b is 25,000 mm ³ , and the third inner lid 3c is attached and sealed with the third seal portion 4c. The internal volume at that time is 12,000 mm ³ . Further, the conventional container has the shape shown in FIG. 2, and the inner volume when the illustrated inner lid is attached is 40,000 mm ³ .

  Each container was filled with 500,000, 1 million and 1.5 million solder balls having a particle diameter of 0.3 mm, and sealed with an inner lid and an outer lid. In the container of the present invention, the third, second, and first inner lids were used corresponding to the number of solder balls, respectively. On the other hand, in the case of the conventional container, the inner lid is one kind as described above.

  A total of six types of containers filled with solder balls were placed on a rotating machine and rotated at a speed of 60 revolutions per minute. After rotating for 20 hours, the luminance of the solder ball surface is measured using a luminance meter. If the luminance value decreases by 20% or more from the luminance value before the test, it is rejected. The degree of conversion was evaluated. Table 1 shows the specifications of each container and the evaluation results of blackening.

  In the containers according to the present invention of Nos. 1 to 3, even if the number of solder balls filled in the container changes greatly, the voids are 10% or less. From the results shown in Table 1, in the container of the present invention, no significant decrease in luminance was observed regardless of the number of solder balls to be filled, and blackening of the solder ball surface could be prevented.

  On the other hand, in the case of conventional containers of Nos. 4 and 5, since the voids were large, the surface of the solder balls was rubbed severely, and the occurrence of blackening was remarkable and failed. In the container of No. 6, since the volume of the solder ball to be filled was appropriate with respect to the inner volume of the container, the gap was relatively small as 10%, and the blackening of the solder ball surface was an acceptable range. .

  Moreover, when the external appearance of the solder ball with which the containers of Nos. 1 to 6 were filled after the evaluation was visually observed, no deformation of the solder ball was observed in any case.

It is a cross-sectional schematic diagram which shows the state by which each of the solder ball containers (1), (2), (3) of the present invention is filled with solder balls. It is a cross-sectional schematic diagram which shows the state with which the solder ball was filled in the conventional container for solder balls.

Explanation of symbols

1 Container body, 2 outer lid, 3 middle lid, 3a first middle lid, 3b second middle lid, 3c third middle lid, 4 seal portion, 4a first seal portion, 4b second seal portion 4c Third seal, 5 Solder ball, 6 Flange, 7 Air gap

Claims (1)

The seal portion formed on the inner wall of the bottomed tubular container body, the container solder ball to seal against the front end outer peripheral portion of the inner lid, the seal portion towards the bottom from the opening of the container body The solder ball container is characterized by having a taper shape whose inner diameter decreases for a while and is provided at two or more locations.

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