JP2867445B2 - Printed circuit board assembly - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a structure for preventing a pin grid array type package from falling when the package is mounted on a printed circuit board. After mounting the pin grid array type package on the front side of the printed circuit board, When the package is mounted on the back side by inverting the printed circuit board and the pin grid array package is mounted on both the front and back surfaces of the printed circuit board, the purpose is to prevent the pin grid array package from falling from the inverted printed circuit board. In a structure in which the pin grid array type package is mounted on both front and back surfaces of a printed circuit board, the package mounted on at least one surface is mounted via a connection auxiliary.

[Industrial applications]

The present invention relates to a pin grid array type package (hereinafter referred to as PGA).
(Referred to as a mold package) on a printed circuit board.

Even in a surface mount type package such as a PGA type package where signal pins are led out of the package body in a multi-column lattice, the semiconductor chip recently mounted on the package is for high power devices Therefore, it is necessary to mount a heavy package having a radiation fin for cooling the semiconductor chip on a printed circuit board by soldering.

By the way, such a PGA type package has heavy radiating fins when soldering and mounting on the front and back surfaces of the printed circuit board, so that the PGA type package mounted on the back side of the printed circuit board is located below the printed circuit board. There is a risk of falling.

Also, in the PGA type package without the above-mentioned radiation fins, if the PGA type package is mounted on both the front and back sides of the printed circuit board because the signal pins are thin, the PGA package mounted on the back side of the printed circuit board will be There is a risk of falling down.

[Conventional technology]

FIGS. 11 (a) to 11 (g) show a method of mounting an electronic component having a large connection area with respect to a footprint on a printed circuit board without a thin signal pin like a PGA type package. Is described.

As shown in FIG. 11A, the solder cream 3 is applied on the footprint 2 of the printed circuit board 1. Next, as shown in FIG. 11 (b), the electrodes 5 of the surface mount type package 4 are placed on the solder cream 3. Next, as shown in FIG. 11 (c), the printed board is passed through an infrared heating furnace to melt the solder cream, and the electrodes 5 of the surface mount type package are soldered to the footprint 2. Next, after the printed board 1 is turned upside down as shown in FIG. 11 (d), a solder cream 3 is applied to the footprint 2 on the back side of the printed board as shown in FIG. 11 (e).
Next, as shown in FIG. 11 (f), a surface-mount type package is placed on the substrate, and the solder is passed again through the infrared heating furnace as shown in FIG. 11 (g).

[Problems to be solved by the invention]

By the way, the surface mounted electronic components other than the PGA type package are mounted on one surface of the printed circuit board, and then, in the solder reflow step of inverting the substrate and melting the solder cream, the electronic component is also printed on the printed circuit board. No more falling. This means that the surface tension of the molten solder is
It is considered that the weight of the package is larger than that of the package of the surface mount electronic component other than the die package.

However, it is considered that the signal pins connected to the printed circuit board of the PGA type package are very thin, and the surface tension of the solder that supports the own weight of the PGA type package is not generated. Therefore, the PGA type package has a structure in which the PGA type package is mounted on only one side of the printed circuit board, and there is no structure in which the PGA type package is mounted on both the front and back surfaces of the printed circuit board.

The present invention solves the above-mentioned problems, and in order to mount the PGA type package on both the front and back surfaces of the printed circuit board, after mounting the PGA type package on the front surface of the printed circuit board, the printed circuit board is turned over and the reverse side is mounted. An object of the present invention is to provide a structure for preventing a PGA type package from falling by its own weight when the PGA type package is mounted.

[Means for solving the problem]

A printed circuit board assembly according to the present invention is a printed circuit board assembly in which a package having a plurality of connection terminals is mounted on both sides of a printed circuit board by soldering, and a first package mounted on one surface of the printed circuit board includes: A connection auxiliary body is provided separately from the connection terminals, and when the second package is mounted on the other surface of the printed circuit board by soldering, the first package is removed from the printed circuit board with melting of the solder. It is characterized by having fixing means for fixing the connection auxiliary body to the printed circuit board so as not to be detached.

The “printed board assembly” referred to here indicates a printed board in which electric components such as a package are mounted on the printed board.

In order to achieve the above object, a structure for preventing a fall of a PGA type package according to the present invention when mounting the PGA type package is shown in FIG. Is mounted via connection auxiliary bodies 21, 31, 41.

Further, as shown in FIG. 2, FIG. 3 (a) and FIG.
A connection auxiliary body that adheres to an inverted printed circuit board outside the outermost periphery of the signal pins 12 arranged in a plurality of rows in parallel with 1 and prevents the package from dropping from the board, specifically, a package. The holding pin 21 is planted.

Further, as shown in FIGS. 4 and 5, the fall prevention structure is formed by penetrating the printed circuit board inside the innermost periphery of the signal pins 12 arranged in plural rows in parallel with the PGA type package 11. It is possible to provide a connection auxiliary body for positioning and fixing the package to the printed circuit board, specifically, a package positioning and fixing pin 31.

Further, as shown in FIGS. 6 and 7, the fall prevention structure is used for the signal pins of the pin grid array type package 11.
In the center of the surface from which 12 is led out, a connection auxiliary body for bonding and fixing the package to the printed circuit board, specifically, a thermal conductive member 41 is arranged.

Further, the method for preventing the PGA package from dropping, as shown in FIG. 8 and FIG.
A flat plate on which a package pressing machine for setting the surface opposite to the surface from which the package is drawn out, specifically, a package main body support tool 35 and means 33 and 34 for pressing the support tool are arranged at predetermined positions. A flat member 37 is provided, and the flat plate member 37 is fixed to a printed circuit board while supporting the package with the pressing means of the support.

Further, as shown in FIG. 10, the above-mentioned method for preventing the PGA type package from dropping is performed by a flat magnet facing the heat radiation fins 14 provided on the surface opposite to the surface from which the signal pins 12 of the PGA type package 11 are led out. 51 is provided, the radiating fins 14 are magnetized so as to have the same magnetic pole with respect to the magnetic pole of the plate-shaped magnet 51 on the side facing the radiating fin, and the plate-shaped magnet 51 is fixed to a printed circuit board. .

(Operation)

As shown in FIG. 2, the PGA type package of the present invention
A package holding pin 21 is provided outside the outermost row of the implanted signal pins 12 separately from the signal pins 12 implanted in the GA type package 11 in a plurality of rows, or as shown in FIG. As described above, the package positioning and fixing pins 31 are provided inside the innermost row of the planted signal pins 12 separately from the signal pins 21 planted in a plurality of rows in the PGA type package 11, so that printing is performed. When the package is mounted on the mounting surface of the board and these package holding pins 21 are bonded to the printed board with an adhesive, the package can be firmly and securely fixed to the printed board. The PGA type package can be firmly and reliably fixed to the printed board by bending the package positioning and fixing pins 31 so as to penetrate the printed board.

In the printed board assembly of the present invention, when the PGA type package 11 shown in FIG. 2 is mounted on the printed board 1 as shown in FIGS. 3 (a) and 3 (b), the package holding pins 21 are printed. When the PGA package 11 is adhered to the substrate 1 with the adhesive 22, the PGA type package 11 can be firmly and reliably fixed to the printed circuit board 1.

When the PGA type package 11 shown in FIG. 4 is mounted on the printed circuit board 1 as shown in FIG. 5, the package positioning and fixing pins 31 are penetrated through the printed circuit board 1 and bent to be bent. Printed circuit board 1
In this case, the PGA type package 11 can be firmly and securely fixed to the printed circuit board 1. Therefore, in both the case of FIG. 3 and FIG. When soldering 11, it is possible to prevent the PGA type package 11 from falling downward.

Further, as shown in FIG. 6 and FIG.
On the surface of the package body 13 in the center of the direction in which the signal pins 12 on the side opposite to the side where the signal pins 12 are provided are drawn, a box-shaped heat conductive member 41 is disposed at a position facing the heat radiation fins 14. Then, when the surface of the thermal conductive member and the printed board are soldered with a large amount of solder, when a package having a radiation fin is soldered to the back side of the printed board by the bonding force of the solder. Parts will not fall to the bottom.

As a method of mounting the PGA type package on a printed circuit board, as shown in FIGS. 8 and 9, a package main body support member 35 for setting a surface of the package main body opposite to a surface from which pins are led out is provided. And a means 33, 34 for pressing the support, disposed at a predetermined position, provided with a plate-like member 37, and fixing the plate-like member to a printed circuit board while supporting the package with the means for pressing the support. Then, the electronic components installed on the back surface of the printed circuit board do not fall down.

Further, as shown in FIG. 10, in the case of the PGA type package having the radiation fins, the signal pins 12 of the PGA type package 11 are provided.
Radiation fins provided on the surface opposite to the surface from which
A plate-like magnet 51 is provided opposite to the heat radiation fins 14.
Are magnetized so as to have the same magnetic pole with respect to the magnetic pole of the plate-shaped magnet 51 on the side facing the radiation fin, and when the plate-shaped magnet 51 is fixed to the printed circuit board, the magnetized radiation fin and the plate-shaped magnet Will repel each other and the PGA type package will not fall down.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a fall prevention structure when mounting a PGA type package of the present invention. As shown, the signal pins 12 of the PGA package 11 are soldered to the footprints 2 formed on the front and back surfaces of the printed circuit board 1 via connection assistants 21, 31, 41. Specifically, these connection auxiliary members are package holding pins 21 implanted outside the outermost periphery of the signal pin 12, or bendable positioning fixing pins implanted inside the innermost periphery of the signal pin 21. Either 31 or a thermally conductive member 41 provided at the center of the side from which the signal pin 12 is led out. By using such a connection auxiliary body, even a surface-mounted electronic component having extremely thin signal pins 12 connected to a footprint such as a PGA type package can be mounted on both front and back surfaces of a printed circuit board.

FIG. 2 is a perspective view of the first embodiment of the PGA type package drop prevention structure of the present invention, as shown in FIG. Of the signal pins 12 derived to
A package holding pin 21 is provided further outside the signal pin 12 implanted on the outermost side.

When the package of this embodiment is soldered to a printed circuit board, the package holding pins 21 and the front surface 1A side of the printed circuit board 1 are fixed using an adhesive 22 as shown in FIG. I do. Next, as shown in FIG. 3 (b), the printed circuit board 1 is turned over and the back surface of the printed circuit board 1 is inverted.
Place the package on 1B side up. And solder cream on both sides of the printed circuit board
Inserting into the heating furnace with 23 applied and the signal pins 12 adhered makes it possible to mount the PGA package on both sides of the printed circuit board without specially requiring an electronic component fixing jig for soldering. Further, in the present embodiment, the structure having the heat radiation fins 14 is employed, but a structure of a PGA type package having no heat radiation fins may be adopted.

FIG. 4 is a perspective view of a second embodiment of a fall prevention structure for a PGA type package according to the present invention. As shown in FIG.
The mold package 11 is provided with pins 31 for positioning and fixing the package further inside than the signal pins 12 implanted inside the package body 13. The length of the package positioning and fixing pin 31 is longer than that of the other planted signal pins 12, and the package positioning and fixing pin 31 is
When the package 11 is mounted on the printed circuit board 1, the package 11 has both functions of positioning the package with respect to the printed circuit board and preventing the package from falling.

When the package of the present embodiment is soldered to a printed circuit board, as shown in FIG. 5, the package positioning and fixing pins 31 are passed through a predetermined position of the printed circuit board 1 and one end thereof is bent. Even when the package is set on the lower surface 1B of the printed circuit board 1, it does not fall.

The package mounted on the front surface 1A of the printed circuit board 1 is cut so that the package positioning and fixing pins 31 are shortened so that the package can be mounted on both sides of the printed circuit board.

It is preferable to provide at least two such package positioning / fixing pins 31 on a diagonal line. Also, the package holding pins and the package positioning / fixing pins 31 described above are used.
Is not a signal pin, so when it becomes necessary to replace the package with another package, it is preferable to cut this package holding pin and replace it with another package. In this embodiment, the structure having the heat radiating fin is used, but the structure without the heat radiating fin may be used.

FIG. 6 is a perspective view of a third embodiment of a fall prevention structure of a PGA type package according to the present invention. As shown in FIG.
A connection auxiliary body, specifically, a box-shaped heat conductive member 41 made of copper is provided on a surface 13B on the back side of the surface 13A of the thirteen at a position facing the heat radiation fins. The shape of the heat conductive member 41 may be a cylindrical shape other than the present embodiment, or may be the same shape as the heat radiation fins 14.

A case where such a package of this embodiment is mounted on a printed circuit board will be described with reference to FIGS. 7 (a) and 7 (b). As shown in FIG. 7 (a), the above PGA
The signal pins 12 of the die package 11A to the surface 1 of the printed circuit board 1.
When soldering to the A-side footprint using a hot-air heating furnace, the above-described thermally conductive member 41 is also soldered to the printed circuit board.

Next, as shown in FIG. 7 (b), the printed circuit board 1 is turned over so that the printed circuit board surface 1A faces down, and the footprint PGA of one surface 1B of the printed circuit board 1B is turned down.
The signal pins 12 of the die package 11B to the back 1 of the printed circuit board 1.
Solder using the B footprint hot air heating furnace.
Even when the printed circuit board is turned over in this way, the thermally conductive member 41 soldered to the front surface 1A of the printed circuit board can have a large amount of solder to be soldered to the printed circuit board. The package is prevented from falling down due to surface tension. Further, the melting of the solder 42 of the heat conductive member 41 facilitates the movement of the package, so that the package can be positioned at a predetermined position on a predetermined printed circuit board and soldered. In addition, the heat generated from the package can be released to the outside through the printed circuit board by the heat conductive member, so that the package can be cooled more efficiently.

According to the PGA type package fall prevention structure of the first embodiment to the third embodiment, a special mounting jig for mounting the package on a printed circuit board is not required.

Also, a method for preventing a package from having the package holding pins or the package positioning / fixing pins shown in the first and second embodiments when the package is not mounted on a printed circuit board will be described.

FIG. 8 is a perspective view of an electronic component installation jig used in the method for preventing a PGA type package from falling according to the present invention.

As shown in the figure, a package pressing machine used for such a package drop prevention method, specifically, an electronic component installation jig 32 is a package installation member including a leaf spring 33, a spring 34, and a package body support 35. 36 is formed from a pallet 37 made of a metal plate arranged at a predetermined position.

Using this electronic component installation jig 32, a PGA type package 1
The case where 1 is mounted on a printed circuit board by soldering will be described.

As shown in FIG. 9, the package body supporting member 35 of the package installation member 36 is provided with the radiation fins 14 of the package.
Frame 38 extending from the side end of the pallet 37 with the
And the printed circuit board 1 are fixed by screws.
37 is placed on a conveyor, and this conveyor is passed through a heating furnace in which a heating gas is injected, and the PGA type package 11
Are soldered to the printed circuit board 1.

Note that the method of this embodiment can be applied to a PGA type package having no heat radiation fins.

FIG. 10 is an explanatory view of another embodiment of the method for preventing a PGA type package from falling according to the present invention.

As shown, the radiation fin 1 of the PGA type package 11
An electronic component installation jig 32 for mounting and mounting the radiating fins 14 for mounting the package on the printed circuit board 1 is formed of the plate-shaped magnet 51, and the radiating fin opposed to the plate-shaped magnet has the same magnetic pole. Magnetize to have. In this way, in the case where the package is mounted on both the front and back surfaces of the printed circuit board 1, the package is first mounted on the front surface 1A side of the printed circuit board 1, and then the substrate is inverted to further separate the printed circuit board. When soldering with the heat radiation fins 14 on the back side of the printed circuit board, a simple operation of fixing the flat magnet 51 to the printed board using a frame 38 or the like with the printed board inverted is performed by a simple operation. I'm done. That is, since the radiation fin 14 and the plate-shaped magnet 51 of the electronic component installation jig have the same magnetic pole, they repel each other and the package does not fall downward, so that complicated leaf springs and spring parts are required. Therefore, the package can be mounted on both sides of the printed circuit board using an electronic component installation jig having a simple configuration.

〔The invention's effect〕

As is apparent from the above description, the first claim
According to the invention described in the paragraph, the PGA type package mounted on one surface of the printed circuit board by soldering is detached from the printed circuit board when the second package is mounted on the other surface of the printed circuit board by soldering. According to the invention described in claim 4, the PGA type package can be firmly attached to the printed board by a plurality of package holding pins having a diameter larger than the pin diameter independently of the signal pins. It is possible to securely fix.

[Brief description of the drawings]

FIG. 1 is a schematic view of a fall prevention structure for mounting a PGA type package of the present invention, FIG. 2 is a perspective view of a first embodiment of a fall prevention structure of a PGA type package of the present invention, and FIG. 3 (b) is a view showing a state in which the package of the first embodiment is mounted on a printed circuit board. FIG. 4 is a perspective view of a second embodiment of the fall prevention structure of the PGA type package of the present invention. FIG. 6 is an explanatory view of mounting the package of the second embodiment on a printed circuit board. FIG. 6 is a perspective view of a third embodiment of a fall prevention structure of a PGA type package of the present invention. FIG. 7 (a) and FIG. b) is an explanatory view of the mounting method of the third embodiment, FIG. 8 is a perspective view of a jig used for the method of preventing the PGA type package from falling according to the present invention, and FIG. 9 is mounting using the jig of FIG. 10 is an explanatory view of a method, FIG. 10 is an explanatory view of another embodiment of a method for preventing a PGA type package from dropping according to the present invention, and FIG. From Figure 11 until the (g) are explanatory views of a mounting method of a conventional electronic component. In the figure, 1 is a printed circuit board, 1A and 1B are printed circuit board surfaces, 11, 11A and 11
B is a PGA type package, 12 is a signal pin, 13 is a package body, 14 is a radiation fin, 21 is a pin for holding a package, 22 is an adhesive, 23 is a solder cream, 31 is a pin for fixing and fixing a package, and 32 is an electronic component. Installation jig, 33 is a leaf spring, 34 is a spring, 35 is a package body support, 36 is a package installation member, 37 is a pallet, 38 is a frame, 41 is a heat conductive member,
42 indicates solder, and 51 indicates a flat magnet.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidehiko Kira 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Kenji Koyae 1015 Kamidadanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 56) References Japanese Utility Model Sho 58-15378 (JP, U) Japanese Utility Model Sho 62-84932 (JP, U) Japanese Utility Model Sho 56-139255 (JP, U) Japanese Utility Model Sho 62-98238 (JP, U) ) Surveyed field (Int.Cl. ⁶ , DB name) H05K 13/04

Claims (3)

(57) [Claims] 1. A printed circuit board assembly in which a package having a plurality of connection terminals is mounted on both sides of a printed circuit board by soldering, wherein the first package mounted on one surface of the printed circuit board has the connection terminals. A second auxiliary package is provided separately from the printed circuit board. When the second package is mounted on the other surface of the printed circuit board by soldering, the first package is not detached from the printed circuit board due to melting of the solder. And a fixing means for fixing the connection auxiliary body to the printed circuit board. 2. The printed circuit board assembly according to claim 1, wherein said connection auxiliary body is formed of metal pins, and said metal pins are fixed to said printed circuit board by a connection resin. 3. The printed circuit board assembly according to claim 1, wherein said connection auxiliary body is bent and locked to said printed circuit board.