JPH0878571A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PURPOSE: To avoid the lead bending for improving the coplanarity by a method wherein wirings extend from one main substrate through sides to the other main surface to form outer leads while receptions are formed on the other main surface. CONSTITUTION: A semiconductor element is directly fixed on one main surface of an insulating substrate 1 so as to bond a wiring 2 of a noble metal plating such as Au etc., formed on this main surface onto a pad of the semiconductor element respectively by Au wires. Next, inner ends of these Au wires, semiconductor element and wirings 2 are covered with a molding resin 3. Especially, the wirings 2 on one main surface extend to the other main surface through the sides of insulating substrates 1 so as to form outer leads. At this time, the surface having no wirings 2 at all out of the other main surface excluding the outer leads is formed into recessions. Through these procedures, the leads will not be deformed even if any external force is given so that the assembling yield may be increased thereby enabling the products in stable coplanarity to be manufactured.

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 structure of an external lead portion and a method of manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor device using a lead frame having a plurality of leads integrally formed on a frame or the like is disclosed in Japanese Unexamined Patent Publication No. 59-23553 (first conventional example) showing a conventional method for manufacturing a semiconductor device. In the package of
While bending the lead before packaging,
A manufacturing method is shown in which the frame and the like are bent in the same direction as the lead bending and in the same amount.

In this conventional manufacturing method, a lead frame is formed by bending a part of a lead, a part of a positioning hole at four corners, and the like from a thin metal plate by pressing, and then the lead frame is placed on a ceramic base to which a semiconductor element is fixed. Place the lead frame, seal with glass, connect the gold wire (wire),
Next, the cap is fixed to the crown, and finally the frame is cut.

Further, with reference to JP-A-63-283147 (second conventional example) showing another conventional semiconductor device, a printed wiring board having through holes is used as a base material, and a semiconductor element is mounted. In the semiconductor package described above, there is shown a semiconductor device in which a brazing material is applied to the through hole and a peripheral portion of the through hole.

Further, referring to Japanese Utility Model Application Laid-Open No. 63-12849 (conventional example 3) showing a conventional integrated circuit package, there is shown a package having external leads covered with a flexible resin film. This package does not require bending of the lead and requires only pressing down on the lead during soldering.

[0006]

SUMMARY OF THE INVENTION The above-described first to third embodiments
Among the conventional examples, first, the first conventional example not only has the drawback that the mold for several steps is required for bending the external lead, and the equipment cost is increased. The assembled semiconductor device has a drawback in that the internal and external leads are easily deformed during assembly to be defective, inspection is required for each process, and a large number of steps are required, which is not economical.

Further, in the second conventional example, through holes are formed in the insulating base material, and it is difficult to arrange a large number of leads in order to prevent these through holes from contacting each other. Therefore, it cannot be used for a semiconductor element having a large number of pins, and has a disadvantage that an insulating substrate has a large area.

The third conventional example has a drawback in that a mounting maker requires a great number of man-hours because soldering by the infrared reflow method which is currently the mainstream in mounting is not possible, and the lead frame also has a feature. Because of the flexible material structure, the holding force of the frame itself is weak, the gold wire after connection will be deformed by the vibration during the process transfer, and a lot of man-hours are required for quality inspection and removal, In addition to the disadvantage that the cost of defective products is large, the lead frame is expensive because the lead frame is manufactured with the same structure as the tape aided bonding film.

In the present invention, in order to solve the above drawbacks,
The following issues are raised.

(1) Do not bend the external leads.

(2) A mold and man-hours required for bending can be omitted.

(3) To be compatible with leads having a multi-pin structure.

(4) To reduce the outer shape of the semiconductor device.

(5) To enable soldering by the infrared reflow method.

(6) Being resistant to mechanical external vibration.

(7) No deformation of the internal lead occurs.

(8) The connection failure of the gold wire due to the deformation of the internal lead does not occur.

(9) An economic burden such as inspection man-hours and defective disposal costs due to deformation should not be increased.

(10) The number of man-hours for mounting should not be increased due to the difficulty of mounting for mounting manufacturers.

(11) Forming external leads so that inspection at the time of mounting can be easily performed by an automatic discriminator.

[0021]

According to the structure of the present invention, a semiconductor element is fixed to one main surface of an insulating substrate, and the wiring formed on the one main surface and the pad of the semiconductor element are connected by wires. In the semiconductor device in which a part of the semiconductor element, the wire, and the wiring is covered with a mold resin, the wiring extends from the one main surface to the other main surface of the substrate through the side surface of the substrate and external leads. In addition, a concave portion is formed on the other main surface of the substrate, and in particular, the concave portion is provided with an adhesive for fixing the semiconductor device.

Further, according to the structure of the present invention, there is provided a step of forming an external lead in which the wiring on the one main surface of the insulating substrate to which the semiconductor element is fixed on one main surface extends through the side surface to the other main surface. In the method for manufacturing a semiconductor device provided, the wiring on the side surface forms a group of through holes corresponding to the external leads on an original substrate including the insulating substrate, and forms a conductor layer on the inner surface of the hole. It is characterized in that it is obtained by partially cutting and removing the through hole, and in particular, the partial cutting of the through hole is performed simultaneously with the cutting of the groove between the frame of the original substrate and the insulating substrate. And

[0023]

1 and 2 are a perspective view and a sectional view, respectively, showing a semiconductor device according to an embodiment of the present invention.

1 and 2, in the semiconductor device of this embodiment, a semiconductor element 4 is fixed directly on one main surface of an insulating substrate 1, and a wiring 2 of noble metal plating such as gold formed on this one main surface. And the pads of the semiconductor element 4 are bonded by gold wires 5, respectively, to form a mold resin 3 that covers at least the inner ends (corresponding to internal leads) of the gold wires 5, the semiconductor element 4, and the wiring 2. The wiring 2 on one main surface extends through the side surface of the insulating substrate 1 to the other main surface to form external leads. A concave portion is formed on the other main surface except for the space between the external leads, where the wiring 2 is not provided, and this is necessary to improve the fixing force and the like during mounting. A large number of the wirings 2 are arranged in a direction perpendicular to the paper surface on both side surfaces in FIG. 2 and form so-called external leads. Since such a large number of wirings 2 are formed on one insulating substrate 1 so as to connect the external leads to each other, there is no fear of deformation as in the conventional case.

Here, the semiconductor element 4 is directly fixed to one main surface of the insulating substrate 1. However, when it is desired to bias the back surface of the semiconductor element 4 to a predetermined potential, the semiconductor element 4 is attached to the main surface of the insulating substrate 1. A single wire 2 is extended and formed into a so-called "island" shape, and a semiconductor element 4 is fixed thereto by a conductive adhesive, and a necessary bias is applied from the outside through the wire 2.

This semiconductor device is surface-mounted by a solder reflow method or the like on a mounting substrate (not shown) on the main surface of which a wiring pattern is formed so as to face the wiring 2.

The concave portion on the other main surface of the insulating substrate 1 has a depth of about 0.125 mm, and a stronger adhesive force can be obtained when an adhesive that adheres to the mounting substrate enters therein. Although the insulating substrate 1 is exposed in this recess, it may be a conductor layer different from the wiring 2. The semiconductor device is fixed to the mounting substrate by the wiring 2 including the side surface and the recess.
The wiring 2 serving as an external lead is formed by plating copper with a noble metal such as gold, but gold may be used as the material.

Width of insulating substrate 1 in FIG. 2 (between both side surfaces)
Is 6.55 mm, its depth is 5.2 mm perpendicular to it, its thickness is 0.5 mm, and the length of the wiring 2 on the other back is 0.6 m
m, the width of the wiring 2 is uniform and 0.4 mm, and the interval between the insulating substrates 1 of the wiring 2 is 0.87 mm.

The width of the molding resin 3 may be large until it becomes equal to the width of the insulating substrate 1.

This semiconductor device is fixed on the mounting substrate to the external leads on the other main surface and the side surface by soldering, but more preferably, an adhesive is provided between the recess and the mounting substrate to obtain the adhesive force. Reinforce. This reinforcing adhesive can be used for temporary fixing before soldering the semiconductor device onto the mounting substrate, and in this case, workability is improved. If an adhesive is provided in advance in the recess, it is preferable to temporarily cover this surface with a seal or the like that is easy to peel off.

The dimensions given in this embodiment may be up to two or three times each dimension.

One method of manufacturing the above semiconductor device will be described below.

Referring to plan views or sectional views of FIGS. 3 to 11 showing one method of manufacturing the semiconductor device shown in FIGS. 1 and 2, first, in FIG. 3, copper is formed on both main surfaces of the original insulating substrate 1 '. A material provided with the foil 6 is prepared.

In the original insulating substrate 1 made of this material, only so-called unit elements corresponding to only one semiconductor element are shown, and in reality, insulating substrates of such unit elements exist continuously on the left and right, It is arranged so as to continuously manufacture a large number of semiconductor devices.

The material of the original insulating substrate 1 'is required to have a heat resistance of at least 150 degrees Celsius, and is therefore preferably made of a material such as a thermosetting resin.

The copper foil 6 may not be necessary when thick electroless copper is to be formed in the next step of FIG.

Next, as shown in FIG. 4, one pin hole (or two pin holes at both ends) which is a feed hole of the substrate 1 at the time of manufacturing and is provided as a positioning is provided. Next, the same number of through holes 7 as the number of necessary external leads are provided.
An electric drill, a laser beam, or the like is used to form the pin hole 10 and the through hole 7. Next, when electroless copper plating is applied to the entire surface of the original insulating substrate 1 'in this state, the copper plating is also applied to the side surfaces of the holes of the through holes 7. The pin hole 10 does not necessarily need copper plating.

Next, as shown in FIG. 5, in order to form the wiring 22 that serves as an inner lead and an outer lead for electrically connecting the semiconductor element with a wire, first, the surface to be the wiring 22 and the side surface and backside of the hole are formed. The surface of the main surface other than the wiring 22 is masked with a resist, and the surface is plated with a noble metal such as gold. Next, the resist is removed, the surface is reverse-masked, and unnecessary portions of the electroless copper plating are removed by etching. In this state, the wiring 22 extends from the main surface to the back main surface via the side surface of the hole.

Next, as shown in FIG. 6, a cutting process is performed along a dotted line 21 in FIG. 5 with a mold or a lute. Here, the groove 20 is provided at 1,000 places so as to be easily cut from the frame 11 in a subsequent process and to prevent the airtightness of the mold resin from being damaged by the stress at the time of cutting. Further, this cutting also cuts off the through hole 7, but the mold is manufactured in advance so that only the portion of the side surface of the hole of the through hole 7 which is continuous with the wiring 22 is left uncut. There is. The part that was cut off is an unnecessary part,
As a result, the insulating substrate 1 is formed, and the planar shape of the semiconductor device becomes smaller. It is preferable that the groove 20 is provided not before the formation of the through hole 7 and the pin hole 10 but after the formation, in order to manufacture the hole processing with high precision.
The groove 20 may be formed using a common mold so that the groove 20 can be formed simultaneously with the partial cutting of the through hole 7.
It is preferable not to increase the number of steps and to improve the cutting processing accuracy.

Referring to FIG. 7, which shows a cross-sectional view taken along the line AA 'of FIG. 6, a concave portion 8 is formed in advance on the back main surface or is formed before or after the step of FIG. The processing method of the concave portion 2 of 2 is a milling method, a method of manufacturing in advance with a die, or the like. The formation of the concave portion 8 is for obtaining a space for applying an adhesive for temporary fixing at the time of mounting on the substrate on the back main surface of the completed semiconductor device.

Thereafter, as shown in FIG. 8, a noble metal plating 2 is applied to the surface of the copper foil 6 of the wiring 22 serving as inner and outer leads formed by etching. In this case, as the noble metal, gold, palladium, or an alloy thereof is used, but since the noble metal plating material is expensive, the noble metal is usually limited to 0.1 μm to 0.3 μm. For that purpose, nickel plating (not shown in the figure) is generally applied under the noble metal plating 2 by 1 μm or more. This nickel plating has the effect of preventing the diffusion of the copper foil 6 and preventing the ultrasonic vibrations from escaping due to the softening of the insulating substrate 1 due to the heat when connecting the gold wire 6.

The precious metal plating performed in the step of FIG. 8 may be omitted if it is applied in the step of FIG.
This step is indispensable when the precious metal plating is not performed in the step shown in FIG.

Next, as shown in FIG. 9, the semiconductor element 4 is mounted on the exposed main surface portion of the insulating substrate 1 with a thermosetting resin adhesive, and then the electrode portion of the semiconductor element 4 is attached to the lead surface. After connecting to the noble metal plating part 2 of with gold wire 5,
As shown in FIG. 0, a molding resin 3 is applied to protect the semiconductor element 4 and the gold wire 5. Then, as shown in FIG.
1 is cut off with a mold or the like to obtain a semiconductor device.

Referring to FIG. 12 which is a perspective view of a lead frame showing another method for manufacturing a semiconductor device of the present invention, in this lead frame, the inner lead portions of the wirings 22 are not radial but are all parallel. The original insulating substrate 1 ′ is arranged thinly, except for the external lead portion when the wiring 22 is the same, but the thickness of the frame 11 outside the line indicated by the dotted line 25 is set to the above-mentioned external. If it is shared with the lead portion, there is an effect that it is easy to cut along the dotted line 25.

FIG. 13 is a cross-sectional view showing a state where the semiconductor device manufactured as described above and shown in FIGS. 1 to 12 is mounted on a mounting substrate. In FIG. 13, the external leads 31 of the semiconductor device 30 are fixed to the wirings 41 on the main surface of the mounting board 40 by soldering, and in this embodiment, the adhesive in the concave portions is removed.

Since the side surfaces of the outer leads 31 are also plated, the meniscus 50 is formed during mounting,
For this reason, the inspection of the mounting state (whether or not soldered) can be easily inspected by the automatic discriminator, which has the effect of reducing the number of inspection steps.

[0047]

As described above in detail, according to the present invention, the above-mentioned problems are solved, and particularly when a resin material is used for the base material of the lead frame, the lead is deformed even when an external force is applied during assembly. As a result, the assembly yield is improved, and it is possible to supply products with stable coplanarity for the same reason.
There is an economic effect that expensive inspection equipment is not required, and since the bending process is not performed on the lead frame itself in the assembly process, the number of steps can be reduced by eliminating the bending process, and bending dies and press equipment etc. There is also an effect that expensive equipment is unnecessary and cost can be reduced.

Further, since the surface of the lead is preliminarily plated with a noble metal, the step of applying solder plating or the like during the assembling is not required, and when constructing the production line, it is possible to simplify and greatly reduce the investment, which is economical. In addition, in the lead frame manufacturing process, through holes are provided, electroless copper plating is performed, and noble metal plating is applied on the through holes, so that the tip side surfaces of the external leads are also plated. The condition is that the fillet can be reliably formed when mounted. This fillet required an enormous amount of man-hours for the mounting user to perform mounting inspection, so it was replaced with an automatic inspection device using laser light. In order to do so, it is an essential element. This fillet has the advantage that it can be reliably formed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor device of FIG.

FIG. 3 is a plan view showing an original insulating substrate prepared by a method of manufacturing a semiconductor device according to the present invention.

FIG. 4 is a plan view showing a state in which hole processing has been performed on the substrate of FIG. 3;

5 is a plan view showing a state in which wiring is formed on the substrate of FIG.

6 is a plan view showing a state where the substrate of FIG. 5 is cut and processed.

7 is a cross-sectional view taken along the line AA ′ of the substrate of FIG.

8 is a cross-sectional view showing a state where the substrate of FIG. 7 is plated.

9 is a plan view showing a state in which semiconductor elements and the like are fixed to the substrate of FIG.

10 is a plan view showing a state where mold resin is applied to the substrate of FIG.

11 is a plan view showing a state where a frame is cut and removed from the substrate of FIG. 10;

FIG. 12 is a perspective view showing a state in which an original insulating substrate used in a semiconductor device according to another embodiment of the present invention has been cut and removed.

FIG. 13 is a side view showing a state of one embodiment of the semiconductor device of the embodiment of the present invention.

[Explanation of symbols]

 1 Insulating substrate 1'Original insulating substrate 2,22 Noble metal plating wiring 3 Mold resin 4 Semiconductor element 5 Gold wire 6 Copper foil 7 Through hole 8 Recess 9 Fixing part 10 Pin hole 11 Frame 20 Groove 30 Semiconductor device 31 External lead 40 Mounting Substrate 41 Wiring 50 Meniscus

Claims (4)

[Claims] 1. A semiconductor element is fixed to one main surface of an insulating substrate, and a wiring formed on the one main surface and a pad of the semiconductor element are connected by a wire, respectively, the semiconductor element, the wire, and the wiring. In a semiconductor device in which a part of is covered with a mold resin, the wiring extends from the one main surface to the other main surface of the substrate through the side surface of the substrate to form an external lead, and to the other main surface of the substrate. Is a semiconductor device having a recess. 2. The semiconductor device according to claim 1, wherein the recess is provided with an adhesive for fixing the semiconductor device. 3. A semiconductor device comprising a step of forming an external lead in which a wiring on the one main surface of an insulating substrate to which a semiconductor element is fixed to the one main surface extends through a side surface to the other main surface. In the manufacturing method, in the wiring on the side surface, a through hole group corresponding to the external lead is formed on an original substrate including the insulating substrate, a conductor layer is formed on the inner surface of the hole, and then the through hole is partially formed. A method of manufacturing a semiconductor device, which is obtained by cutting and removing. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the partial cutting of the through hole is performed simultaneously with the cutting of the groove between the frame of the original substrate and the insulating substrate.