JPH06833Y2 - Highly moisture-resistant lead frame for optical semiconductor devices sealed with transparent resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a lead frame. In particular, for example, CD
The present invention relates to a lead frame having a high moisture resistance for an optical semiconductor device, which is sealed with a transparent resin such as a photo detector for use in a semiconductor device.

[Summary of the Invention] In a lead frame of the present invention, a plurality of recesses are formed in a member that supports a pad portion on which a semiconductor chip of a lead frame of an optical semiconductor device sealed with a transparent resin is formed. At least a part of the extension of the portion where the recess is formed is formed to be bent so that the path length of moisture that enters can be long, and at least a portion of the portion where the recess is formed of this member is Forming a narrow width prevents moisture such as moisture from entering from the outside through the lead frame, and further prevents the intrusion of the semiconductor chip into the periphery of the die pad part on which the semiconductor chip is mounted. By having a plurality of guide portions for mounting at two or more desired different angles with respect to the reference line, the semiconductor chip can be mounted in a desired direction indicated by the guide portions, and different The semiconductor chip having the above-described shape can be used universally, and the mounting direction can be accurately determined in one specific direction for each guide portion.

[Conventional technology]

In a conventional lead frame, for example, a lead frame used for a semiconductor device, a pad on which a semiconductor chip is mounted and an external lead are continuous, and therefore moisture or other moisture from the outside may penetrate through the lead and enter the inside. was there.

For example, an optical semiconductor device such as a photodetector for a compact disc CD has a structure in which it is sealed with a transparent resin. The above-mentioned problems are particularly important for an optical semiconductor device sealed with a transparent resin in this way. Is. This is because, as the transparent resin for sealing the optical semiconductor device, the light transmittance thereof is most important, so that it is not always possible to select one having good moisture resistance. Thus, in the conventional CD photodetector, etc.,
For example, the cathode electrode is often used also as a die pad and as an external lead, but in this case, there is the above-mentioned problem.

That is, conventionally, as shown in FIG. 8, the external lead a is directly maintained integrally with the die pad b with its lead width maintained. No special measures have been taken so far on the surface of the connection portion c, and the surface of the connection portion c is treated in the same manner as the external lead a.
For this reason, external moisture and moisture may be transmitted to the external leads a and enter the die pad b of the optical semiconductor device, which may adversely affect the device. For example, there is a possibility that the device may be broken due to corrosion of aluminum or the like due to the intrusion of water, or a leak may occur. In the case of the one as shown in FIG. 8, water or the like may enter from the interface between the sealing transparent resin forming the body B and the connecting portion c of the external lead a. As described above, the opto-semiconductor device is selected as the encapsulating resin that is highly transparent to the corresponding light as the most important selection criterion. Therefore, this is not always compatible with the moisture resistance. However, the encapsulating resin does not always protect and protect the entry of such moisture.

Therefore, the illustrated path P of the length of the portion connecting the die pad b and the external lead a, including the die pad suspension portion, that is, the connection portion c in the case of the illustrated conventional example, that is, the center of the die pad b and the body width W is shown. Although it is conceivable to take measures such as increasing the length, if the leads are lengthened in plan to lengthen the path P, the space becomes large and it becomes impossible to miniaturize and miniaturize. In addition, if the path P is bent around on a plane without taking up too much space and is drawn around and lengthened, contact may occur. Further, it is difficult to set a distance for leading the leads, for example, for those requiring a fine lead frame structure. In general, it is often impossible to take a sufficient path even if the leads are laid out, and it is often difficult to lay out the leads. Therefore, it is not practical for a microfabricated structure such as an optical semiconductor device.

[Problems to be solved by the invention]

As described above, in the conventional lead frame of the optical semiconductor device, moisture such as moisture from the outside may penetrate through the leads, which is caused by the transparent resin. It was very problematic. Moreover, trying to solve this problem of moisture intrusion by increasing the path length by routing the lead, etc., remained a space and processing problem, so it was not a sufficient solution. is there.

On the other hand, for example, an optical semiconductor device used as a photodetector for a compact disc CD needs to mount a semiconductor chip at a position having a certain directionality in order to obtain information on the disc. This is because the direction in which the pickup moves on the disk is determined by the position of the motor that is the drive source, and therefore the most efficient position for receiving the signal is determined.

However, the direction is not the same for all CDs, and will change depending on the CD model. As described above, the moving direction of the pickup is determined by the position of the motor. However, since the installation position of the motor differs depending on the model, the moving direction of the pickup also differs depending on the model. Along with this, the installation direction of the photodetector is changing.

That is, the mounting direction of the photodetector must be fixed for a specific model, but it must be fixed for other models.

By the way, with respect to various conventional lead frames for semiconductor devices, there has not yet been proposed a technique for utilizing the lead frame to regulate the mounting direction for each model.

The present invention solves the various problems of the prior art as described above and devises the structure of the lead frame to prevent the ingress of moisture such as moisture and has high humidity resistance, and it is necessary to take up space. It is easy and versatile, and even when various devices are mounted at various angular positions as described above, and when semiconductor chips of different sizes are used, the work is easy and versatile. It is intended to provide a highly moisture-resistant lead frame for an optical semiconductor device, which can be carried out with a certain angle and can always achieve accurate mounting at a certain angle.

[Means for solving problems]

In order to solve the above-mentioned problems, a highly moisture-resistant lead frame of an optical semiconductor device sealed with a transparent resin of the present invention has a plurality of recesses formed in a member supporting a pad on which the semiconductor chip is mounted. In addition, at least a part of the extension of the portion of the member where the recess is formed is formed to be bent, thereby extending the path of moisture that enters, and at least one of the portions of the member where the recess is formed. And a plurality of guide portions for mounting the semiconductor chip at two or more desired different angles with respect to a reference line of the die pad portion, the guide portion being provided at a peripheral portion of the die pad portion. In addition, the guide part is formed by a corner that is the outer shape of the die pad part, or a side that is the outer shape of the die pad part and that has a predetermined angle with respect to the reference line. It is made by, and said die pad has a pair of leads to the pair of opposing portions, taking the guide portion and has a configuration to another pair of opposing portions intersecting the pair of opposing portions.

[Action]

In the lead frame of the present invention, due to the plurality of recesses and the bending structure, the path is lengthened to prevent entry of moisture and the like, and at least a part of the part where the recess is formed is formed to be narrow, This prevention of water intrusion can be further ensured. As a result, a lead frame having high humidity resistance can be obtained. Further, when mounting a semiconductor chip on the die pad portion of the lead frame, the semiconductor chip is always mounted in a fixed direction if the semiconductor chip is placed in accordance with the guide portion provided on the die pad portion. Also, since this guide part is provided in a plurality so as to indicate two or more different mounting directions, when it is used for a certain model, it is mounted according to one guide part indicating one mounting direction, When used for other models, it can be mounted according to the guide part showing the other mounting direction. In this way, the semiconductor chip can be mounted in any direction out of the mounting directions indicated by the guide portion, so that even a single lead frame is highly versatile. In addition, the semiconductor chip can be always mounted in a fixed direction indicated by the guide portion if it is aligned with the desired guide portion. (See Examples below).

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Of course, the present invention is not limited to the embodiments described below.

In this embodiment, the present invention is applied to a CD photodetector.

This embodiment is particularly effective in applying the present invention because it is an example in which moisture is disliked in terms of size and material, and therefore high moisture resistance is required.

That is, in the embodiment described below, the package size of the semiconductor chip 2 is as small as 4.0 × 5.0 as shown in FIG. 2, and the die pad portion 11 shown in FIG. The path p from the center of the part where the pallet is mounted to the outline of the package is designed to be as short as 2.0 mm, and as shown in FIG. 3, the cathode K of the device is connected to the die pad part 11 to suspend the die pad. Therefore, structurally, moisture from the outside,
The device may be broken or leaked by entering through the interface between the resin and the lead.

Further, in this example, a resin having not so high moisture resistance is used in order to improve the permeability. That is, the photodetector for CD receives the laser beam and also has important functions such as tracking, focusing and photoelectric conversion, and it is necessary to transmit the laser beam efficiently. Therefore, the transmittance at 780 nm is high. It is common to use transparent resin that does not contain filler. In this embodiment, the encapsulation with the transparent resin is performed by a package forming method using a method called transfer molding. The transparent transfer molding resin used here is denoted by reference numerals I and I in FIG.
As shown by I and III, a relatively poor treatment occurred within a relatively short treatment time in the moisture resistance test, and a general black resin containing a filler (for example, EME61 manufactured by Sumitomo Bakelite Co., Ltd.) was used.
It is inferior in moisture resistance by one digit or more compared to (such as 00) (note that I is a pheno type resin, and II and III are acid anhydride type resins).

As described above, in the present example, since the resin itself having poor moisture resistance is used and the size is made small, it is an important problem to improve the moisture resistance by some measure.

A lead frame 1 according to this embodiment is shown in FIG. As shown in FIG. 1, the lead frame 1 has a plurality of recesses 12 formed in a member 1a supporting a pad portion 11 on which a semiconductor chip (denoted by reference numeral 2 in FIG. 2) is mounted. At least a part of the portion where the recess 12 is formed is formed narrow. This narrow portion is indicated by reference numeral 13.
In this example, the portion near the pad portion 11 of the portion where the recessed portion 12 is formed is formed to be narrow, that is, the ridge is attached to the die pad portion 1.
The narrow portion 13 is formed by constricting the width direction from 1
As a result, moisture is prevented from entering and moisture resistance is improved.

In this embodiment, as shown in the cross section in FIG. 5, the recesses 12 are provided on the upper and lower surfaces of the lead frame 1 and are formed so as to form a wedge having an angle of 60 ° as shown. If there are a plurality of recesses 12, the desired effect can be achieved, and it is not necessary that they are on both the upper and lower sides, but it is more effective if they are on both sides.

Further, in this embodiment, the concave portions 12 are alternately formed on the upper and lower surfaces to further enhance the effect.

Furthermore, in the present embodiment, as shown by reference numeral 14 in FIG. 1, the portion of the lead frame 1 connected to the external lead is bent to lengthen the path. With this, the moisture-proof effect was further enhanced.

That is, in this embodiment, the distance L ₁ of the external lead to the die pad center and the distance L ₂ between the die pad center and the connecting portion are made different. For example, L ₁ -L ₂ = 0.28
And

Further, as shown by reference numeral 15 in FIG. 3, a plurality of R bends can be formed to make the path meander, and the path length can be further lengthened to determine the effect.

Further, in this embodiment, the width W _{2 of the} connecting portion is made smaller than the width W _{1 of the} external lead (for example, 0.4 and 0.3) so as to further enhance the effect.

(Note that Japanese Utility Model Publication No. 49-18591 discloses a technique in which a recess is formed in a lead. However, the moisture resistance is not a problem in this technique, and the narrow portion as in the present invention is disclosed. Is contrary to the expected effect of the technique described in the publication, and is a technique unrelated to the present invention).

In this embodiment, as shown in FIG. 1, guide portions 3, 4 and 5 indicating the mounting direction of the semiconductor chip are provided on the periphery of the die pad portion 11 on which the semiconductor chip is mounted, as shown in the figure. Has been. The guide parts 3, 4, 5 indicate two or more mounting directions of different semiconductor chips, and a plurality of guide parts are provided. The guide portion 3 (consisting of the guide portions 31 to 33) determines the mounting direction of the semiconductor chip in the direction of 0 degree with respect to the reference line 1. Guide part 4 (guide part 4
1 to 43) defines the mounting direction of the semiconductor chip in the direction of 30 degrees with respect to the reference line 1. The guide part 5 (consisting of the guide parts 51 and 52) determines the mounting direction of the semiconductor chip in the direction of 45 degrees with respect to the reference line 1.

When the lead frame 1 of the present embodiment is used, as a result of applying the present invention, it is possible to give versatility to mounting a semiconductor chip as follows. That is, as shown in FIG. 3A, when it is desired to mount the semiconductor chip 2 in the direction of an inclination of 0 degrees with respect to the reference line 1, the center of the die pad portion 11 and the semiconductor chip 2 are aligned with each other. Guide part 3 (3
1, 32, 33), the semiconductor chip 2 is mounted in the direction of 0 ° with respect to the reference line 1 by mounting the semiconductor chip 2.

Further, when it is desired to mount the semiconductor chip 2 in a direction with an inclination of 30 degrees with respect to the reference line 1 as shown in FIG. 3 (b), the guide portion 4 (41, 42, 43) of the die pad portion 11 is also used.
Then, the semiconductor chip 2 is placed.

Further, as shown in FIG. 3C, when it is desired to mount the semiconductor chip 2 in a direction of 45 degrees with respect to the reference line 1, the semiconductor chip 2 is aligned with the guide portion 5 (51, 52) of the die pad portion 11. Place 2. Thereby, the guide portion 3,
The semiconductor chip 2 can be mounted in a desired direction corresponding to 4, 5. In addition, since the direction of the semiconductor chip 2 is always fixed if it is adjusted to a specific guide portion, the semiconductor chip 2 can be mounted with the necessary fixed directionality according to the model.
In this case, since it is convenient to determine the reference position of the semiconductor chip, a pattern indicating the reference position of the semiconductor chip is formed on the die pad portion.

That is, here, as shown by reference numerals 61 to 64 in FIG.
A mark indicating the center of the die pad portion 11 was inserted. A cross section of this mark is shown in FIG. Further, circular grooves 7 having the same center as the die pad portion 11 were intermittently formed in the die pad portion 11. This cross section is shown in FIG. The groove 7 and the marks 61 to 64 function as a pattern indicating the reference position of the semiconductor chip 2. By doing so,
The die bond position (including the inclination direction determined by the guide portions 3, 4, 5) can be accurately obtained.

The present invention can be applied not only to the CD as in the above example, but also to those that take a signal from a video disk, a laser disk, or other disks, or any other materials that require moisture proofness, and can be applied as appropriate. However, the invention is not limited to the embodiments described and illustrated above.

[Effect of device]

As described above, the lead frame of the present invention is effective in preventing the ingress of moisture such as moisture, has high moisture resistance, requires less space, and is easy to process. Further, according to the present invention, the mounting direction of the semiconductor chip can be set to an arbitrary direction by taking any one of a plurality of angles indicated by the guide unit. It can be placed at various positions. Moreover, even if the shape of the semiconductor chip is different, there is versatility. As a result, it is possible to easily achieve accurate placement while meeting various conditions.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the lead frame of the present invention. FIG. 2A is a plan view of a semiconductor chip used in this embodiment, and FIG. 2B is a side view. 3 and 4 are views for explaining the embodiment. 5 is a sectional view taken along the line CC of FIG. 1, FIG. 6 is a sectional view taken along the line AA, and FIG. 7 is a sectional view taken along the line BB. FIG. 8 is a diagram showing a conventional example. 1 ... Lead frame, 11 ... Die pad part, 2 ... Semiconductor chip, 12 ... Recessed part, 13 ... Narrow part.

Claims (1)

[Scope of utility model registration request] 1. A member supporting a die pad part on which a semiconductor chip of a highly moisture-resistant lead frame of an optical semiconductor device sealed with a transparent resin is formed, and a plurality of recesses are formed in the member. At least a part of the extended portion of the recessed portion is formed to be bent so that the path of moisture that enters can be lengthened, and at least a portion of the portion of the member where the recess is formed is formed to be narrow. And a plurality of guide portions for mounting the semiconductor chip at two or more desired different angles with respect to a reference line of the die pad portion, the guide portion having a plurality of guide portions at the peripheral portion of the die pad portion. Is a corner portion which is the outer shape of the die pad portion,
Alternatively, it is formed by a side that is an outer shape of the die pad portion and has a predetermined angle with respect to the reference line, and the die pad portion has a pair of leads at a pair of opposing portions thereof, A highly moisture-resistant lead frame for an optical semiconductor device sealed with a transparent resin, characterized in that the guide portion is provided at another pair of facing portions that intersect with the pair of facing portions.