JP4657129B2 - Manufacturing method of semiconductor device - Google Patents

Description

The present invention relates to a method of manufacturing a semi-conductor device, in particular, to a method of manufacturing a semiconductor device having a lead frame adhesion with the sealing resin is achieved.

  As the semiconductor device, there is a resin-encapsulated semiconductor device in which a semiconductor chip is encapsulated with an encapsulating resin. As shown in FIG. 11, in this type of semiconductor device 101, the semiconductor chip 103 is mounted at a predetermined position of the lead frame 105, and in that state, is sealed with a sealing resin 107 such as a mold resin.

  Next, a method for manufacturing such a semiconductor device 101 will be briefly described. First, as shown in FIG. 12, the lead frame 105 is punched into a predetermined shape in advance. At this time, the lead frame is punched out by a predetermined mold, and as shown in FIG.

  Next, by coining a predetermined area of the lead frame 105 with a predetermined mold, as shown in FIGS. 14 and 15, the burr 110 generated at the time of punching is pressed to the area of the lead frame 105. A recess 111 is provided. Thereafter, the semiconductor chip 103 is die-bonded to the region of the depression 111 by a preform 109 (see FIG. 11) such as silver paste. Then, the semiconductor device 101 shown in FIG. 11 is manufactured by being sealed by the sealing resin 107 together with the lead frame 105.

  By the way, if the adhesion between the sealing resin 107 and the lead frame 105 is not good, due to the heat generated by the operation of the semiconductor device 101 and the difference in the thermal expansion coefficient between the lead frame 105 and the sealing resin 107, The sealing resin 107 may peel off from the surface of the lead frame 105. When the sealing resin 107 is peeled from the lead frame 105, a gap is generated between the sealing resin 107 and the lead frame 105, moisture or the like enters through the gap, moisture resistance deteriorates, and the reliability of the semiconductor device 101 is impaired. May be.

Therefore, as shown in FIG. 16, the surface of the lead frame 105 is preliminarily processed to form an uneven surface 105 a, and the contact area between the sealing resin 107 and the lead frame 105 is increased. And the lead frame 105 are in close contact with each other. Note that there is Patent Document 1 as one of documents that disclose this kind of technology.
JP-A-5-226563

  However, the conventional semiconductor device 101 has the following problems. As shown in FIG. 16, the uneven surface 105a formed by pressing the surface of the lead frame 105 becomes comparatively uneven. For this reason, even if the contact area between the sealing resin 107 and the lead frame 105 can be increased to some extent, if the semiconductor device 101 is operated for a long time under a high temperature and humidity, the sealing resin 107 is removed from the lead frame 105. There is a possibility that the reliability of the semiconductor device 101 is impaired.

The present invention has been made to solve the above problems, the purpose of that method of manufacturing a semiconductor device in which example Bei lead frame adhesiveness is further enhanced reliability is improved further with the sealing resin Is to provide.

A manufacturing method of a semiconductor device according to the present invention is a manufacturing method of a semiconductor device in which a semiconductor chip die-bonded to a lead frame is sealed, and includes the following steps. A concave portion and a convex portion are formed on the surface of the lead frame by pressing with a first pressing member in which a predetermined protrusion is formed on a portion in contact with the lead frame (first first pressing step). After the first first pressing step, the first pressing member used in the first first pressing step is used, and the relative positional relationship of the first pressing member with respect to the lead frame is the same as in the first first pressing step. The first pressing member is disposed so as to be different from the relative positional relationship of the first pressing member with respect to the lead frame, and the concave portion and the convex portion are formed on the surface of the lead frame by pressing the first pressing member with the disposed first pressing member. Are further formed (second first pressing step). After the first pressing step, the key portion extending to the side is crushed by pressing the tip portion of the convex portion located between the concave portions by pressing the lead frame with the flat second pressing member. Form (second pressing step). After the second pressing step, the semiconductor chip is die-bonded with a preform interposed on the lead frame. The semiconductor chip die-bonded to the lead frame is sealed with a sealing resin.

According to this method, the key portion extending to the side is formed by crushing the convex portion located between the plurality of concave portions formed on the surface of the metal thin plate in the first pressing step in the second pressing step. It can be formed easily. As a result, when the semiconductor chip and the lead frame are sealed with the sealing resin, the portion of the sealing resin that has entered the recess is hooked by the key portion, and the sealing resin adheres to the surface of the lead frame. As a result, even if the semiconductor device is operated for a long time under high temperature and humidity, the sealing resin is prevented from peeling from the lead frame, and the reliability as the semiconductor device is greatly improved. be able to.

Another method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device in which a semiconductor chip die-bonded to a lead frame is sealed, and includes the following steps. A concave portion and a convex portion are formed on the surface of the lead frame by pressing with a first pressing member in which a predetermined protrusion is formed on a portion in contact with the lead frame (first first pressing step). After the first first pressing step, the first pressing member used in the first first pressing step is used, and the positional relationship between the first pressing member and the lead frame is the first in the first first pressing step. By pressing with the first pressing member under a positional relationship that is relatively different from the positional relationship between the pressing member and the lead frame, a concave portion and a convex portion are further formed on the surface of the lead frame (second time First pressing step). After the first pressing step, the key portion extending to the side is crushed by pressing the tip portion of the convex portion located between the concave portions by pressing the lead frame with the flat second pressing member. Form (second pressing step). After the second pressing step, the semiconductor chip is die-bonded with a preform interposed on the lead frame. The semiconductor chip die-bonded to the lead frame is sealed with a sealing resin.

According to this method, the key portion extending to the side is formed by crushing the convex portion located between the plurality of concave portions formed on the surface of the metal thin plate in the first pressing step in the second pressing step. It can be formed easily. As a result, when the semiconductor chip and the lead frame are sealed with the sealing resin, the portion of the sealing resin that has entered the recess is hooked by the key portion, and the sealing resin adheres to the surface of the lead frame. As a result, even if the semiconductor device is operated for a long time under high temperature and humidity, the sealing resin is prevented from peeling from the lead frame, and the reliability as the semiconductor device is greatly improved. be able to.

The shape of the protrusion of the first pressing member is preferably a quadrangular pyramid.

Further, the protrusion of the first pressing member may be rounded.

The protrusions of the first pressing member are arranged with a predetermined pitch, and in the second pressing step, the first pressing member is relative to the relative positional relationship of the first pressing member with respect to the lead frame in the first pressing step. It is preferable that the pitch of the protrusions is shifted by a half pitch.

In the die bonding step, it is preferable that the preform is interposed between the lead frame and the semiconductor chip so as to enter the concave portion of the lead frame.

In the sealing step, it is preferable that the sealing resin seals the semiconductor chip in such a manner that the sealing resin enters the recess of the lead frame.

The method includes forming a lead frame by punching a metal foil plate into a predetermined shape, and flattening burrs generated by punching the metal foil plate after the first pressing step and before the second pressing step. It is preferable to include a punching step.

The first pressing step preferably includes a step of further pressing the lead frame after the second first pressing step, in such a manner that the convex portions located between the concave portions are crushed by the first pressing member. The lead frame may have a thickness of 125 μm .

Embodiment 1
A lead frame and a semiconductor device including the lead frame according to the first embodiment of the present invention will be described. As shown in FIG. 1, in the resin-encapsulated semiconductor device 1, the semiconductor chip 3 is mounted at a predetermined position on the lead frame 5, and in this state, the semiconductor chip 3 and the lead frame 5 are sealed with mold resin or the like. Sealed with a stop resin 7. The semiconductor chip 3 is die-bonded to the lead frame 5 with a preform 9 interposed on the lead frame 5.

  As shown in FIG. 2, a concavo-convex portion 6 is formed on the surface of the lead frame 5, and a key portion 5c is formed at the tip of the convex portion 5b located between the concave portion 5a and the concave portion 5a. Has been. The key portion 5c is formed by crushing the tip of the convex portion 5b of the concave and convex portion 6, and the side intersecting the depth direction of the concave portion 5a so as to hook the sealing resin 7 that has entered the concave portion 5a of the concave and convex portion 6 Extends towards.

  In the semiconductor device 1 described above, the concavo-convex portion 6 is formed on the surface of the lead frame 5, and the key portion 5c is formed at the tip portion of the convex portion 5b. Thereby, when the semiconductor chip 3 and the lead frame 5 are sealed with the sealing resin 7, the portion of the sealing resin 7 that has entered the concave portion 5a of the concave and convex portion 6 in the lead frame 5 is hooked by the key portion 5c. The sealing resin 7 is in close contact with the surface of the lead frame 5.

  As a result, even if the semiconductor device 1 is operated for a long time under high temperature and humidity, the sealing resin 7 is prevented from being peeled off from the lead frame 5, and the reliability as the semiconductor device 1 is improved. It can be greatly improved. In addition, as compared with the case where the concavo-convex portions are formed by chemically etching the surface of the lead frame, as will be described later, since only mechanical processing by a predetermined processing punch is performed, an increase in production cost is minimized. Can be suppressed.

  When this semiconductor device 1 was subjected to a humidification evaluation prescribed by JEDEC (Joint Electron Device Engineering Council), MSL (Moisture Stress Level) level 1 (storage condition: temperature 85 ° C.) that could not be achieved by a conventional semiconductor device. / Relative humidity 85% RH or less, storage period: indefinite). The relative humidity refers to the ratio between the actual partial pressure of water vapor in the air and the saturated water vapor pressure at that temperature.

Embodiment 2
Next, a method for manufacturing the semiconductor device 1 including a method for forming the above-described uneven portion 6 on the surface of the lead frame 5 will be described. First, as shown in FIGS. 3 and 4, the lead frame 5 is punched into a predetermined shape in advance by a mold. Next, as shown in FIG. 5, protrusions are made on the surface of the portion of the lead frame 5 located in the region (inside the dotted line frame) sealed with the sealing resin in the lead frame 5 based on a predetermined arrangement pattern. The punching process is performed twice by the processing punch 20 on which 20a is formed, and then the punching process by the processing punch having a flat surface is performed. The shape of the protrusion 20a is, for example, a quadrangular pyramid.

  This punching process will be described in more detail. As shown in FIG. 6, a plurality of protrusions 20a having a predetermined pitch are formed on the surface of the processing punch 20 used for the first two punching processes. First, in the first stage A, a punching process is performed based on a predetermined relative positional relationship of the machining punch 20 with respect to the lead frame 5, and a recess 5 a corresponding to the protrusion 20 a is formed on the surface of the lead frame 5. Is done. When the punching process in stage A is completed, the lead frame 5 is transported to the next stage B.

  In the stage B, as shown in FIG. 7, the second time in a positional relationship in which the pitch P of the protrusion is shifted by a half pitch with respect to the relative positional relationship of the machining punch 20 with respect to the lead frame 5 in the stage A By subjecting the lead frame 5 to the punching process, the recess 5a is formed at a position different from the position of the recess 5a formed in the stage A.

  When the punching process in stage B is completed, the lead frame 5 is transported to the next stage C. In stage C, by punching the surface of the lead frame 5 with the processing punch 21 having a flat surface, the tip of the convex portion 5b positioned between the plurality of concave portions 5a formed on the surface of the lead frame 5 is formed. The key part 5c is formed by being crushed.

  Next, the semiconductor chip 3 is die-bonded by the preform 9 to the surface of the lead frame 5 on which the key portion 5c is formed. Then, a predetermined lead frame portion (external lead) in the lead frame 5 and the semiconductor chip 3 are electrically connected by, for example, a gold wire. Thereafter, the lead frame 5 on which the semiconductor chip 3 is mounted is mounted on a predetermined mold (not shown), and a sealing resin 7 such as a mold resin is poured into the mold, whereby the semiconductor chip 3 and the lead frame 5 Is sealed. The semiconductor device 1 shown in FIG. 1 is completed by bending a portion of the lead frame 5 protruding from the sealing resin 7 in a predetermined direction.

  In the manufacturing method described above, by performing the second punching process so that the recesses 5a are formed at positions different from the positions of the plurality of recesses 5a formed on the surface of the lead frame 5 by the first punching process, The surface of the lead frame 5 can be further roughened to increase the surface area, and the number of convex portions 5b positioned between the concave portions 5a and the concave portions 5a can be increased. Thus, a larger number of key portions 5c can be formed by performing the third punching process on the convex portion 5b. As a result, the sealing resin 7 is hooked by the key portion 5c, and the adhesion between the sealing resin 7 and the lead frame 5 can be further improved.

  Further, in the manufacturing method described above, only mechanical processing by the predetermined processing punches 20 and 21 is performed, so that the cost is about 20 compared with the cost in the case where the unevenness is formed by chemically etching the surface of the lead frame. The semiconductor device 1 having excellent adhesion between the sealing resin 7 and the lead frame 5 can be manufactured at a cost of 1 /, and an increase in manufacturing cost can be minimized.

  In the manufacturing method described above, the case where the recess 5a is formed on the surface of the lead frame 5 by using the processing punch 20 having the same projection 20a as the processing punch used for the first two punching processes is taken as an example. I gave it as an explanation. In addition, as shown in FIG. 8, for example, two processing punches 20 and 22 having different protrusion arrangement patterns may be used. That is, in the first punching process, the machining punch 20 in which the projections 20a are formed with a predetermined pitch P is used, and in the second punching process, the projections 22a in which the projection pitches are shifted by a half pitch are formed. A punch 22 is used.

  In this case, in stage B, the second punching process by the processing punch 22 is performed on the lead frame 5 under the same positional relationship as the relative positional relationship of the processing punch 20 with respect to the lead frame 5 in the stage A. become. Also by such a method, the uneven | corrugated | grooved part 6 provided with the same key part 5c can be formed.

  In the manufacturing method described above, the case where the concave portion 5a is formed by performing the punching process twice on the surface of the lead frame 5 has been described as an example. However, as shown in FIG. The number of punching processes for forming the plurality of recesses 5a in the lead frame 5 is as long as the key 5c can be formed by crushing the projections 5b located between the plurality of recesses 5a. It is not limited to twice, and may be once or three or more times.

  In particular, the punching process is performed a plurality of times by the processing punches 20 and 21 on which the protrusions are formed, so that the recesses 5a formed by the initial punching process are projected to a position different from the position of the recesses 5a. When the portion 5b is punched, a portion in which the lead frame 5 extends in a direction intersecting the depth direction of the recess 5a is easily formed, and this becomes a key portion 5c to form the sealing resin 7 and the lead frame. 5 can be further improved.

  In the concave portion 5a of the concave-convex portion 6 formed on the surface of the lead frame 5 in this manner, the depth D is, for example, several times with respect to the thickness of the lead frame 5 of about 125 μm, for example, depending on the number of times punching is performed. The width L is about several μm to several tens of μm, for example.

  In addition, although the processus | protrusion 20 and the processus | protrusion 20a of 22 and demonstrated as an example the processus | protrusion of a quadrangular pyramid shape, the several recessed part 5a was formed in the surface of the lead frame 5, and between the several recessed parts 5a is demonstrated. The projection is not limited to a quadrangular pyramid shape as long as it can crush the tip of the convex portion 5b located at a position to form the key portion 5c. Therefore, if the key portion can be formed even with a protrusion whose tip portion is not sharp, for example, a processing punch capable of forming a concave and convex portion 6 having a rounded bottom of the concave portion 5a as shown in FIG. May be used.

  Further, after punching into a predetermined shape as a lead frame, before performing punching with a processing punch provided with a protrusion, punching may be performed to flatten burrs generated when punching.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the terms of the claims, rather than the scope described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is sectional drawing of the semiconductor device which concerns on embodiment of this invention. FIG. 2 is a partial enlarged cross-sectional view of the semiconductor device shown in FIG. 1 in the same embodiment. FIG. 2 is a plan view showing a step in the method for manufacturing the semiconductor device shown in FIG. 1 in the embodiment. FIG. 4 is a cross-sectional view taken along a cross-sectional line IV-IV shown in FIG. 3 in the same embodiment. In the same embodiment, it is the elements on larger scale which show the processing punch which is used for punching processing. FIG. 4 is a partial plan view showing a punching process using a processing punch, which is performed after the step shown in FIG. 3 in the embodiment. FIG. 7 is a partially enlarged plan view showing two machining punches used in the punching process shown in FIG. 6 in the same embodiment. FIG. 7 is another partially enlarged plan view showing two machining punches used in the punching process shown in FIG. 6 in the same embodiment. In the same embodiment, it is the elements on larger scale for explaining the feature of the punching processing with the processing punch. In the same embodiment, it is the elements on larger scale of another semiconductor device. It is sectional drawing of the conventional semiconductor device. FIG. 12 is a plan view showing a step in the method for manufacturing the semiconductor device shown in FIG. 11. It is sectional drawing in sectional line XIII-XIII shown in FIG. It is a top view which shows the process performed after the process shown in FIG. It is sectional drawing in sectional line XV-XV shown in FIG. FIG. 12 is a partial enlarged cross-sectional view of the semiconductor device shown in FIG. 11.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Semiconductor device, 3 Semiconductor chip, 5 Lead frame, 5a Concave part, 5b Convex part, 5c Key part, 6 Concave-convex part, 7 Sealing resin, 9 Preform, 20, 21, 22 Processing punch, 20a, 22a Protrusion.

Claims (10)

A method of manufacturing a semiconductor device in which a semiconductor chip die-bonded to a lead frame is sealed,
A first pressing step for forming a concave portion and a convex portion on the surface of the lead frame by pressing with a first pressing member having a predetermined protrusion formed on a portion contacting the lead frame;
After the first first pressing step, the first pressing member used in the first first pressing step is used, and the relative positional relationship of the first pressing member with respect to the lead frame is the first time. By disposing the first pressing member so as to be different from the relative positional relationship of the first pressing member with respect to the lead frame in the first pressing step, the first pressing member is pressed by the arranged first pressing member, A second first pressing step of further forming a concave portion and a convex portion on the surface of the lead frame;
After the first pressing step, a portion in contact with the lead frame is pressed by a flat second pressing member, thereby crushing a tip portion of the convex portion located between the concave portions and extending sideward. A second pressing step for forming a key portion to be performed;
After the second pressing step, a step of die bonding a semiconductor chip with a preform interposed on the lead frame;
Sealing the semiconductor chip die-bonded to the lead frame with a sealing resin;
A method for manufacturing a semiconductor device, comprising: A method of manufacturing a semiconductor device in which a semiconductor chip die-bonded to a lead frame is sealed,
A first pressing step for forming a concave portion and a convex portion on the surface of the lead frame by pressing with a first pressing member having a predetermined protrusion formed on a portion contacting the lead frame;
After the first first pressing step, the first pressing member used in the first first pressing step is used, and the positional relationship between the first pressing member and the lead frame is the first first pressing step. By pressing with the first pressing member under a positional relationship that is relatively different from the positional relationship between the first pressing member and the lead frame in one pressing step, the surface of the lead frame is depressed and protruded. A second first pressing step for further forming a portion;
After the first pressing step, a portion in contact with the lead frame is pressed by a flat second pressing member, thereby crushing a tip portion of the convex portion located between the concave portions and extending sideward. A second pressing step for forming a key portion to be performed;
After the second pressing step, a step of die bonding a semiconductor chip with a preform interposed on the lead frame;
Sealing the semiconductor chip die-bonded to the lead frame with a sealing resin;
A method for manufacturing a semiconductor device, comprising: The method of manufacturing a semiconductor device according to claim 1, wherein a shape of the protrusion of the first pressing member is a quadrangular pyramid. The method of manufacturing a semiconductor device according to claim 1, wherein the protrusion of the first pressing member is rounded. The protrusions of the first pressing member are arranged with a predetermined pitch,
In the second pressing step, the pitch of the protrusions of the first pressing member is only a half pitch relative to the relative positional relationship of the first pressing member with respect to the lead frame in the first pressing step. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is shifted. 6. The method of manufacturing a semiconductor device according to claim 1, wherein, in the die bonding step, the preform is interposed between the lead frame and the semiconductor chip so as to enter the concave portion of the lead frame. . The method for manufacturing a semiconductor device according to claim 1, wherein, in the sealing step, the sealing resin seals the semiconductor chip in a mode of entering the concave portion of the lead frame. Forming the lead frame by punching a metal foil plate into a predetermined shape;
The semiconductor device according to claim 1, further comprising a punching step for flattening burrs generated by punching the metal foil plate after the first pressing step and before the second pressing step. Manufacturing method. The first pressing step includes, after the second first pressing step, a step of further pressing the lead frame in a manner of crushing the convex portions located between the concave portions by the first pressing member. A method for manufacturing a semiconductor device according to claim 1 or 2. The method of manufacturing a semiconductor device according to claim 1, wherein the lead frame has a thickness of 125 μm.

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