JPH0982873A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set outer terminals extending from the lower opening of the connection holes of a board as high as prescribed and uniform in height, enhanced in reliability, and formed through a simpler process by a method wherein a solder rod is inserted into the connection holes of the board, and the protruding part of the solder rod from the second main surface of the board is made to serve as an outer terminal. SOLUTION: A semiconductor device 1 is mounted on a first main surface 31 of a board 2, and an outer terminal 10 is made protrude from the second main surface of the board 2. A conductive wiring 6 and an outer terminal 10 are electrically connected to a connection through-hole 7 or a connection half hole provided to the board 2 through a connecting means. A solder rod 9 is made to protrude continuously from the second main surface 32 of the board 2 through the connection through-hole 7 to serve as an outer terminal 10. The tip of the outer terminal 10 is kept unchanged in shape when it is cut and not formed into a hemisphere which appears when solder is fused. By this setup, the outer terminal 10 can be mounted without being thermally treated and cleaned, so that a device of high quality can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a surface mount type PGA (Pin Grid A) in which pins serving as external terminals are arranged in a grid pattern.
rray) or BGA (Ball Grid Arr)
The present invention relates to a structure of an external terminal provided directly below a connection hole such as a through hole in an ay) type semiconductor device and a method for forming the external terminal.

[0002]

2. Description of the Related Art FIG. 6 shows, for example, JP-A-62-12374.
FIG. 3 is a cross-sectional view of a BGA type semiconductor device of the related art as disclosed in Japanese Patent Publication No. The semiconductor element 1 is mounted on the first main surface (front surface) 31 of the printed circuit board 2 by the mount material 3, electrically connected to the conductor wiring 6 on the printed circuit board by the bonding wire 4, and then the sealing resin 5 is formed. To seal.

A through hole 7 is formed in the substrate 2, and the through hole 7 is filled with a filling solder 15 for connecting to the conductor wiring 6 on the upper surface by a molten solder by a dipping method or a heat reflow method after applying a solder paste. Further, a solder protrusion 16 is formed from the second main surface (rear surface) 32 of the substrate, the solder having a semi-spherical tip due to melting of the solder is formed to form the external terminal 10.

Further, FIG. 7 shows a prior art P of a pin insertion type.
A sectional view of a GA type semiconductor device is shown. After inserting a metal pin 17 which has been pre-plated with solder into a through hole 7 which is made of a metal film and which is formed in advance on the inner wall of the through hole conductive film 8 which is connected to the conductive wiring 6, the tip end of the pin is inserted. A ball-shaped solder pool 18 is formed by solder dipping to form the external terminal 10. Through hole diameter is 0.2
~ 0.4 mm. The pin diameter including the solder plating may have a projection that is the same as or slightly larger than the diameter of the through hole determined by the inner diameter of the through hole conductive film 8. In this case, the metal pin of the through-hole conductive film 8 and the metal pin including the solder plating are deformed and the metal pin is press-fitted and inserted. Since the thickness of the solder plating is as thin as about 5 μm, it is unstable after the pins are inserted. Therefore, it is necessary to apply a solder coat with a solder dip for fixing. Further, the solder pool 18 at the tip of the pin protruding from the second main surface (back surface) 32 of the substrate serves as a solder ball, and the tip becomes the external terminal 10 having a hemispherical shape of solder.

[0005]

In the solder filling type shown in FIG. 6 described above, it is difficult to fill the solder, and voids are likely to occur. Further, there is a large variation in the amount of protrusion of the hemispherical solder at the tip, which is sufficient. It's difficult to get high. The standoff height after surface mounting is required to be 0.25 mm or more, which is the minimum height for cleaning after mounting. Therefore, it is necessary to secure the protrusion height of 0.5 mm or more for a semiconductor device. There is. However, there is a large variation in the height of the protruding portion, and it is not uncommon for some of the protrusions to exceed 0.2 mm to 1 mm, and it is almost impossible to reduce the coplanarity to 0.15 mm or less. Furthermore, if there is a void in the molten solder after mounting, it goes upside down in the through hole,
The amount of solder on the protruding portion is reduced, and there is a problem in that sufficient mounting solder connection cannot be obtained. In addition, the flux often remains in the through hole, which easily corrodes the conductive film in the through hole and is likely to cause disconnection failure.

On the other hand, in the prior art shown in FIG. 7, similarly, the non-uniformity of the solder volume due to the solder dip is large,
It's very difficult to control. in addition,
To prevent the pin from falling out, use a pin insertion part with a diameter larger than the through hole and insert it by press-fitting, and the pin is harder.Therefore, after the pin is inserted into the board, the volume expansion of the board tends to cause the entire board to warp. It was For this reason, the tip length of the pin is varied, which greatly hinders coplanarity. Furthermore, when the board is thin, the pins cannot be fixed in a stable manner, and it is difficult to stand vertically, which further deteriorates coplanarity.

Further, as can be said for the semiconductor devices of both prior arts shown in FIGS. 6 and 7, the number of steps is reduced because a heat history for completely melting the solder and a flux cleaning step are required to form the external terminals. Increased and prone to quality problems. The dipping method to the molten solder for forming the external terminals requires a heat treatment at about 240 ° C., and since the use of flux is unavoidable, the flux must be washed after the treatment. In addition, when connecting external terminals before assembling a semiconductor device, it is necessary to protect the semiconductor element mounting portion and the inner leads by taping or the like in advance, which necessitates an increase in the number of steps. A semiconductor device using a printed circuit board has a lot of moisture absorption, and has a defect that when the entire surface is heated to a reflow heating temperature of about 240 ° C during surface mounting, peeling of the board and cracking of the resin are likely to occur. For this reason, a dry bake before mounting was essential. Therefore, the same applies to soldering when attaching external terminals when assembling a semiconductor device using a printed circuit board, and the semiconductor device must be dried and baked before solder dipping and reflow, which poses a problem of requiring man-hours.

Therefore, an object of the present invention is to uniformly arrange the solder external terminals under the connection holes of the board with a predetermined height.
It is an object of the present invention to provide a semiconductor device which can be formed with high reliability and a simplified process, and a manufacturing method thereof.

[0009]

A feature of the present invention is that a semiconductor element is mounted on a first main surface of a substrate, and external terminals project from the second main surface of the substrate, and the semiconductor device is arranged on the substrate. In a semiconductor device in which a conductor wire and the external terminal are electrically connected through a connecting means in a through hole or a half hole provided in the substrate, a solder bar is continuously provided from the inside of the connection hole. A semiconductor device in which the external terminal is formed by projecting from the second main surface of the substrate, and the tip of the external terminal is not in a hemispherical state after solder melting but in a state in which the solder rod is cut. It is in.

Another feature of the present invention is that the semiconductor element is mounted on the first main surface of the substrate, the external terminals are projected from the second main surface of the substrate, and the conductor wiring and the conductor wiring arranged on the substrate are provided. In a method of manufacturing a semiconductor device in which an external terminal is electrically connected through a connecting means in a through hole or a half hole connecting hole provided in the substrate,
In the method of manufacturing a semiconductor device, a solder rod is inserted into the connection hole, and the protruding portion of the solder rod protruding from the second main surface of the substrate is used as the external terminal.

In the above semiconductor device or the method of manufacturing a semiconductor device, the solder of the solder bar may be in a state of being mechanically inserted without being melted and fixed to the conductive film on the inner wall of the connection hole. Alternatively, after the solder rod is mechanically inserted, at least a part of the solder bar may have an unmelted portion so that only a part of the solder is melted. Further, the solder rod is composed of two or more kinds of solder having different melting points, and the melting point of the solder arranged in the axial direction of the rod can be made higher than the melting point of the solder on the outer peripheral surface of the rod. Alternatively, a core material made of metal or alloy can be provided in the axial center direction of the solder rod. Further, solder containing the flux of the solder rod can be used.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1A is a sectional view showing a semiconductor device and a method of manufacturing the same according to the first embodiment of the present invention.
FIG. 1B is a cross-sectional view showing an enlarged main part of FIG.

On the printed board 2 in which the pattern of the conductive wiring 6 is formed on the first main surface (front surface) 31 of an insulating substrate such as a glass epoxy substrate, a plurality of inner walls are formed by the through-hole conductive film 8 of a metal film. A through hole 7 is provided so as to penetrate from the first main surface (front surface) 31 of the substrate to the second main surface (back surface) 32, and the conductive film 8 serves as at least a part of the connecting means and a predetermined portion of the conductive wiring 6. Are connected to each.

The semiconductor element 1 is bonded and mounted on the element mounting portion of the conductive wiring 6 on the surface of the printed circuit board 2 by the mounting material 3, and the electrodes of the semiconductor element and the conductive wiring 6 on the printed circuit board are bonded by the bonding wires 4. After being electrically connected to each other, they are sealed with the sealing resin 5.

Then, a through-hole 7 having a through-hole conductive film 8 formed on the inner wall of a solder rod 9 which has been extruded in the shape of a wire in advance or cooled and solidified by an ejection method and mechanically cut into a predetermined length. It is mechanically press-fitted into the second main surface so as to protrude from the second main surface by a predetermined length. This protruding solder protrusion 16 of the solder rod serves as an external electrode as it is. Depending on the case, after that, heat treatment may be performed at a temperature lower than the temperature at which the solder is completely melted, and only a part of the solder may be melted and fused to the through-hole conductive film 8. In any case, the tip of the solder protrusion 16 that becomes the external terminal 10 is not in a hemispherical shape after melting the solder, but is in a state in which the solder rod is cut. After the solder rod is inserted into the through hole, it can be mechanically cut into a predetermined length without variation in height (projection amount) among a large number of external terminals.

The solder of the solder rod 9 is eutectic solder Sn63-Pb.
37 is preferred. The diameter of the through hole 7 defined by the diameter of the solder bar 9 and the inner diameter of the conductive film 8 is 0.1 to 0.
About 8 mm is suitable in the selected range of 0.2 to 0.4 mm, and the length of the solder rod of the solder protruding portion 16, that is, the length from the back surface of the board to the tip is selected to be about 0.2 to 0.8 mm. The optimum range is 0.4 to 0.6 mm. The solder protrusion 16 has a planar shape that reflects the planar shape of the through hole because the press-fitted solder rod 9 is directly protruded. That is, in this embodiment, since it is a circular through hole, the solder protrusion 16 has a cylindrical shape, and does not have a hemispherical shape due to solder melting and solder dipping as in the conventional case.

The length of the solder rod 9 of the solder protrusion 16 is determined by the amount of molten solder and the height of the connection bump during mounting.
Further, it is preferable to provide a protrusion on the board insertion portion of the solder rod in order to have a crimping effect. This solder rod is melted by heat reflow at the time of mounting and bump-connected.

FIG. 2 is a partially enlarged sectional view showing a solder connection state after mounting the semiconductor device of the first embodiment shown in FIG.

The protruding portion of the solder rod is melted by heat reflow during mounting, and the solder protruding portion 16 (FIG. 1) of the solder rod, that is, a cylindrical shape is formed on the wiring film 21 formed on the surface of the mounting substrate 20. Solder connection portions 19 are formed in a bump shape from the external terminals 10 (see FIG. 1) and connected. When implementing this,
The amount of solder may be replenished by printing solder paste on the mounting board side in advance.

FIG. 3 is a sectional view showing an essential part of the second embodiment of the present invention, which corresponds to FIG. 1 (B). A through-hole conductive film 8 is formed on a printed circuit board 2 which constitutes a semiconductor device.
Is formed on the inner wall of the through hole 7, and the solder rod 9 is press-fitted into the through hole 7 and has a solder protruding portion 16 serving as an external electrode 10. The solder rod 9 of this embodiment has a core material 11 in the axial center direction and an outer peripheral portion solder 12 in the outer circumferential portion. For the core material 11, for example, Sn10-Pb90 high melting point solder is used, and for the outer peripheral portion solder 12, for example, eutectic solder Sn63-Pb37 of low melting point solder is used. The composition of the high melting point solder may be selected such that the melting point thereof is equivalent to or higher than the heating reflow temperature during mounting. Further, iron-nickel 42 alloy, or metal or alloy such as copper or phosphor bronze can be used for the core material. In this case, it is preferable to use a solder rod thinned by a drawing method as the solder rod. Considering the stress reduction, a copper-based alloy having an expansion coefficient close to that of the substrate and the solder is superior. It is recommended that the tip of the solder rod be made to protrude and the length thereof be selected from the required height of the standoff after mounting. In this embodiment, 0.5
Approximately 2 mm is suitable, but 0.5-1 mm is particularly preferable. Further, it is preferable that the diameter of the core material is about 0.1 to 0.3 mm and the solder thickness of the outer circumferential portion is about 0.05 to 0.2 mm.
When a metal or alloy is used for the core material, a buffer metal such as nickel plating may be interposed if necessary. In the above cases, the height of the standoff can be controlled to a desired value, and since the repair after mounting also has the core material, the function as an external terminal is maintained even after removing it from the mounting board. Can be implemented. Similar to the first embodiment, the shape of the tip of the protruding portion, the cutting timing of the solder rod, or if necessary, only a part of the outer circumferential solder is welded to the conductive film.

FIG. 4 is a partially enlarged sectional view showing a solder connection state after mounting the semiconductor device of the second embodiment shown in FIG. The core material 11 is not melted during heating reflow, but the solder 12 on the outer circumferential portion of the protruding portion is melted and the bump-shaped solder connection portion 1 is formed.
9 is formed and connected to the wiring film 21 of the mounting substrate 20. Even in this case, if the solder paste is supplied, a good connection can be achieved.

FIG. 5 is a sectional view showing an essential part of a third embodiment of the present invention, which corresponds to FIG. 1 (B) and FIG.
The internal conductive wiring 22 is provided inside the printed circuit board 2, and the half hole 13 having the half hole conductive film 14 as an inner wall reaches the internal conductive wiring 22 from the second main surface (back surface) 32 of the substrate 2. It is provided, and the solder rod 9 is inserted therein from below. It should be noted that the connection hole of this embodiment is not a sulu hole penetrating the substrate 2 from the first main surface 31 to the second main surface 32, but from the second main surface 32 to the inside of the substrate. It is called a half hole. The half-holes of the board are provided by forming through holes only in the board stacking section 2A corresponding to the press-fitting section of the board and stacking the remaining board stacking sections 2B to complete one board before stacking the boards. it can. The method of inserting the soldering rod into the half hole is as described above. In this embodiment, since the upper part of the substrate is closed, it is possible to prevent the solder and the core material from crawling up after mounting, and it is more effective to secure the accuracy of the standoff value and the coplanarity.

Although not shown in the figure, if a flux-filled type is selected for the solder of the solder rod, the flux supply at the time of mounting becomes unnecessary, and the number of steps can be reduced or more stable mounting can be realized.

Although the embodiment of the present invention has been described by taking the BGA as an example, it goes without saying that the present invention is also applicable to a butted lead PG type of a lead type pad.

[0026]

As described above, according to the present invention, it is possible to arrange the terminals as the external terminals by inserting the soldering rods into the through holes or the connecting holes of the half holes of the board. It is possible to attach the external terminals of the semiconductor device without heat treatment and without cleaning the flux. This not only reduces the number of man-hours in the assembly process of the semiconductor device, reduces the materials and utility costs, but also enables the elimination of the heat treatment and cleaning, which eliminates the process, and has higher quality and higher reliability. It becomes possible to realize a semiconductor device. Also, since the printed circuit board absorbs a large amount of moisture, it is easy to cause peeling of the substrate due to water vaporization and deterioration of the resin during heating reflow.If necessary, a dry bake is required before heating reflow. Although the dry baking of the semiconductor device was required before, such dry baking before the formation of the external terminals is unnecessary in the present invention.

Further, according to the present invention, since the solder rod is used as the external terminal while being inserted into the connection hole, the height of the protruding portion from the substrate can be set to a desired value, and the height between the external terminals can be set. It has a good coplanarity in which the dispersion of the solder is suppressed, and the good uniformity of the solder volume can be maintained. Further, it is possible to suppress the warpage of the substrate by filling the inside of the hole without generating voids. Further, since the external terminals can be formed without performing heat treatment or the like, disconnection in the connection holes can be avoided and the external terminals can be easily formed before the semiconductor device is assembled.

Further, if the core material is used in the center of the shaft for the solder rod,
The standoff after mounting can be secured in a desired size, and not only the mounting yield but also the reliability is improved due to the effect of stress relaxation after mounting. Further, since heat treatment is not required to attach the solder rod, it is possible to contain flux in the solder rod, and it is possible to prevent oxidation after mounting and ensure connection reliability.

As described above, it is possible to provide a more reliable semiconductor device while reducing the labor cost for assembly by 50% to 20% as compared with the prior art.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention,
7A is a cross-sectional view of a semiconductor device, and FIG. 6B is a cross-sectional view showing an enlarged main part of FIG.

FIG. 2 is a cross-sectional view showing a main part of a mounted state of the semiconductor device according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a main part of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of a mounted state of a semiconductor device according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of a mounted state of a semiconductor device according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a conventional semiconductor device.

FIG. 7 is a cross-sectional view showing another conventional semiconductor device.

[Explanation of symbols]

 1 Semiconductor Element 2 Substrate 2A, 2B Substrate Laminated Section 3 Mounting Material 4 Bonding Wire 5 Sealing Resin 6 Conductive Wiring 7 Through Hole 8 Through Hole Conductive Film 9 Solder Bar 10 External Terminal 11 Core Material 12 Outer Circumferential Solder 13 Half Hole 14 Half-hole conductive film 15 Charged solder 16 Solder protrusion 17 Metal pin 18 Solder pool 19 Solder connection 20 Mounting board 21 Wiring film 22 Internal conductor wiring 31 First main surface (front surface) 32 Second main surface (back surface)

Claims (10)

[Claims] 1. A semiconductor element is mounted on a first main surface of a substrate, an external terminal projects from a second main surface of the substrate, and the conductor wiring and the external terminal arranged on the substrate are the substrate. In a semiconductor device electrically connected through a connecting means in a through hole or a half hole provided in a semiconductor device, a solder rod is continuously protruded from the second main surface of the substrate from the inside of the connecting hole. The semiconductor device is characterized in that the external terminal is formed by using the external terminal, and the tip of the external terminal is not in a hemispherical state after melting the solder but is in a state in which the solder rod is cut. 2. The solder of the solder rod is mechanically inserted without being melted and fixed to the conductive film on the inner wall of the connection hole, or at least a part thereof has an unmelted portion. The semiconductor device described. 3. The solder rod is composed of two or more kinds of solder having different melting points, and the melting point of the solder arranged in the axial center direction of the rod is higher than the melting point of the solder on the outer peripheral surface of the rod. The semiconductor device according to claim 1 or 2. 4. The semiconductor device according to claim 1, further comprising a core material made of metal or alloy in the axial center direction of the solder rod. 5. The semiconductor device according to claim 1, wherein the solder of the solder rod contains a flux. 6. A semiconductor device is mounted on a first main surface of a substrate, external terminals project from the second main surface of the substrate, and conductor wiring arranged on the substrate and the external terminals are provided on the substrate. In a method of manufacturing a semiconductor device that is electrically connected through a connecting means in a connection hole of a through hole or a half hole provided in, a solder rod is inserted into the connection hole, and the solder rod is the first substrate of the substrate. 2. A method for manufacturing a semiconductor device, characterized in that a protruding portion protruding from the second main surface is used as the external terminal. 7. After inserting the solder rod, a heat treatment is performed at a temperature lower than a temperature at which the solder is completely melted, and at least a part has an unmelted portion, and the conductive film on the inner wall of the connection hole and the solder rod. 7. The method for manufacturing a semiconductor device according to claim 6, wherein a part of the semiconductor device is melted and fixed. 8. The solder rod is composed of two or more kinds of solder having different melting points, and the melting point of the solder arranged in the axial center direction of the rod is higher than the melting point of the solder on the outer peripheral surface of the rod. The method for manufacturing a semiconductor device according to claim 6 or 7. 9. The method of manufacturing a semiconductor device according to claim 6, further comprising a core material made of a metal or an alloy in the axial center direction of the solder rod. 10. The method of manufacturing a semiconductor device according to claim 6, wherein the solder of the solder rod contains a flux.