JP2936669B2 - Resin-sealed semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention seals a main body component including a semiconductor element and a terminal lead-out mechanism of the semiconductor element with a first sealing resin,
Further, the present invention relates to a resin-sealed semiconductor device in which the semiconductor device is sealed with a second sealing resin.

[Prior Art] A main component including a semiconductor element is sealed with a first sealing resin, and the first sealing resin body is further sealed with a second sealing resin.
A semiconductor device which is sealed with a sealing resin of the type described in JP-A-63-4215, for example, has a structure intended to improve moisture resistance.
No. 1 or JP-A-64-37043. Further, as shown in JP-A-64-91498,
It is also considered that the connector housing is formed around the outer periphery of the second sealing resin body to improve the function.

However, by further sealing the first sealing resin body with the second sealing resin body, the thermal stress generated by the thermal stress increases, and the semiconductor element of the main body constituting portion and the first sealing resin body are sealed. A peeling phenomenon may occur between the resin and the resin stopper. Therefore, deterioration of the moisture resistance and further deterioration of the function occur, which causes a problem in reliability.

Further, as shown in Japanese Patent Application Laid-Open No.
It is considered that the sealing resin body is made of a soft resin material having a low elastic modulus. However, in this case, a heat sink made of, for example, aluminum cannot be integrally formed, and the thermal conductivity of the first sealing resin body also deteriorates. Therefore, there is a functional loss due to heat generation of the semiconductor chip portion, which causes a reduction in reliability.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and has a double sealing structure with a first sealing resin body and a second sealing resin body. However, the thermal stress generated between the semiconductor element sealed by the first sealing resin body and the first sealing resin body is effectively reduced, and the reliability as well as the moisture resistance are reliably improved. It is an object of the present invention to provide a resin-encapsulated semiconductor device.

[Means for Solving the Problems] In a resin-encapsulated semiconductor device according to the present invention, a main component including a semiconductor element and other terminal lead-out mechanisms is encapsulated with a first encapsulating resin body, and the first encapsulating resin is used. The first sealing resin body is covered with the second sealing resin body. The linear expansion coefficient α2 of the second sealing resin body is larger than the linear expansion coefficient α1 of the first sealing resin body. Set smaller.

[Operation] In the resin-encapsulated semiconductor device configured as described above, the degree of shrinkage of the second encapsulation resin body generated during cooling depends on the degree of shrinkage generated in the first encapsulation resin body. Since the degree is smaller than the degree, the compressive stress of the first sealing resin body is reduced by the action of the second sealing resin body during this cooling. Therefore, the thermal stress generated between the semiconductor element sealed by the first sealing resin body and the first sealing resin body is effectively reduced. Therefore, the peeling phenomenon occurring between the first sealing resin and the semiconductor element is suppressed, and the reliability is remarkably improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional structure of the semiconductor device 11. The semiconductor device 11 is made of, for example, silicon or the like as a base material, and the semiconductor device 11 is mounted on a metal frame 12 by a bonding agent 13 made of solder or Ag paste. It is mounted by joining. A lead 14 composed of a base material made of a conductive material such as an alloy containing copper as a main component or a 42 alloy is provided around the semiconductor element 11, and the lead 14 and the lead-out of the semiconductor element 11 are provided. The terminals are connected by bonding wires 15 of Al, Au, Cu, or the like. Although not shown in detail, the leads 14 are used for connection between the semiconductor device and the outside of the semiconductor device.

Here, the frame 12 on which the semiconductor element 11 is mounted and the leads 14 are usually formed as a lead frame from a single plate material by pressing, photoetching or the like.

The main component of the semiconductor device including the semiconductor element 11, the lead 14, the bonding wire 15, and the like is sealed by a first sealing resin body 16 made of an epoxy resin or the like. The element is the first sealing resin body
Fixed by 16.

The first sealing resin body 16 is further sealed and fixed by a second sealing resin body 17 made of a thermoplastic resin such as PPS or PBT, or an epoxy-based or silicon-based thermosetting resin. .

Here, as shown in FIG. 2A, a protruding band 18 is formed around the upper surface and the lower surface of the first sealing resin body 16 so as to surround it. Protruding band
In sealing the main body component of the semiconductor device,
It is formed when the sealing resin body 16 is molded.

The protruding strip 18 may be formed only on one surface of the first sealing resin body 16, and may be continuously formed particularly over the entire circumference as shown in FIG. There is no need to form.

Then, the second sealing resin body 17 is
The first and second sealing resin bodies 16 and 17 are integrally connected to each other so that the protruding strips 18 formed in the first and second portions are embedded.

In such a semiconductor device, the coefficient of thermal expansion α of the second sealing resin body 17 is set to be smaller than the coefficient of thermal expansion α1 of the first sealing resin body 16.

When the resin-encapsulated semiconductor device is cooled from a high temperature state, the semiconductor element 11 and the first encapsulation resin body 16 are caused by a difference in linear expansion coefficient between the semiconductor element 11 and the first encapsulation resin body 16. Thermal stress is generated at the interface of the resin stopper 16. This thermal stress peels off the interface between the semiconductor element 11 and the first sealing resin body 16 and reduces the life of the bonding wire 15,
Further, it may cause a passivation crack.

The thermal stress generated at the interface as described above can be summarized by the relationship between the linear expansion coefficient α1 of the first sealing resin body 16 and the linear expansion coefficient α2 of the second sealing resin body 17 as follows. Become.

FIG. 3 shows a model of the semiconductor device shown in FIG. 1 in a three-layer structure, in which the cross-sectional area of each layer is indicated by Ax, the Young's modulus is indicated by Ex, and the linear expansion coefficient is indicated by αx. Assuming that thermal stresses generated in the semiconductor element 11 and the first and second sealing resin bodies 16 and 17 when a temperature change of ΔT is given in this model are σs, σ1 and σ2, respectively,
It is expressed by the following determinant.

When the stress σs applied to the semiconductor element 11 is obtained, the result is as follows.

Therefore, the linear expansion coefficient α2 of the second sealing resin 17 is set to “α”
By setting 1> α2 ″, σs can be reduced.

FIG. 4 shows the relationship between the linear expansion coefficient α2 of the second sealing resin body 17 and the thermal stress. The meaning of this figure is that the thermal stress generated at the interface between the semiconductor element 11 and the first sealing resin body 16 is reduced by reducing the linear expansion coefficient α2 of the second sealing resin body 17. That is what you can do.

That is, in the conventional example, the semiconductor element and the first
The thermal stress generated at the interface of the sealing resin body of σ2c, σ1
(Point C and Point 1 in the figure), but with the configuration shown in the embodiment, the linear expansion coefficient α2 of the second sealing resin By making the expansion rate smaller than α1, the generated thermal stress can be reduced to σ2b (point b in the figure). Further, in a structure that is not sealed by the second sealing resin body 17, the thermal stress σ generated at the interface between the semiconductor element 11 and the first sealing resin body 15 at the time of cooling.
o (point O in the figure), the linear expansion coefficient α2 of the second sealing resin body 17 is By doing so, it can be reduced to σ2a (point a in the figure).

Here, the thermal stress σo when the second sealing resin body 17 is not provided
Is obtained as follows.

σo = K ｛C + E2A2 (α2-α1)｝ A2 = 0, so Next, when the linear expansion coefficient αo that becomes σo when the second sealing resin body 17 is present is obtained, the following is obtained.

Solving the above equation for αo gives the following:

In a state where the second resin sealing body 17 does not exist, the frame cut surface is exposed, and the moisture resistance decreases due to the invasion of moisture from the end face portion. However, as shown in FIG.
By double sealing with the sealing resin body 16 and the second sealing resin body 17, the end face of the frame 12 is covered,
The moisture resistance can be improved.

Further, by making the linear expansion coefficient α2 of the second sealing resin body 17 smaller than the linear expansion coefficient α1 of the first sealing resin body 16, the effect of reducing thermal stress can be obtained in the following cases. Be demonstrated.

First, if the final shape of the package is not changed, it is necessary to design the package to maintain a certain thickness in order to maintain the mechanical strength of the package or to ensure moisture resistance. Therefore, when the double molding structure is adopted, the thickness of the first sealing resin body 16 is reduced to near the molding limit, and then the thickness of the second sealing resin body 17 required for design is reduced. Molding. At this time, the second sealing resin body
If the material is selected so that the linear expansion coefficient α2 of the first sealing resin 17 is smaller than at least the linear expansion coefficient α1 of the first sealing resin body 16, the resin cross-sectional area A of the single mold and the first sealing resin of the double molding can be obtained. The cross-sectional area A1 of the sealing resin body 16 and the cross-sectional area A2 of the second sealing resin body 17
As long as the sum A ′ (= A1 + A2) with the
Stress generated at the interface between the resin and the resin can be reduced.

Secondly, if the package becomes large due to the molding of the second sealing resin body 17, and if the package has a sufficient thickness in view of the molding limit as in the first case, the second Expanding the size by molding the sealing resin body 17
This can be compensated for by reducing the size of the first sealing resin body 16 or the like. However, when the first sealing resin body 16 is reduced to the vicinity of the molding limit, it is inevitable that the size is increased by the second sealing resin body 17. Accordingly, the linear expansion coefficient α2 of the second sealing resin body 17
However, by selecting a material smaller than αo as described above, it is possible to reduce the thermal stress even when the package is enlarged, as compared with a single-mold package.

If such a relationship is satisfied in terms of material properties, thermal stress can be reduced. However, in order to further enhance the effect of reducing the thermal stress, the protruding strip 18 must be formed at least in the first sealing resin body.
By forming it on the edge of the upper surface or the edge of the lower surface of 16, the anchor effect at the interface between the first sealing resin body 16 and the second sealing resin body 17 is exhibited. Further effects can be expected.

In order to improve the adhesion or the adhesion between the first sealing resin body 16 and the second sealing resin body 17, in the embodiments described above, the projecting belt 18 is formed by the first sealing resin body 16. Formed on the surface. However, this structure can be arbitrarily selected. For example, as shown in FIG. 6A, a groove 181 may be formed on at least the upper surface or the lower surface of the first sealing resin body 16. . Also, as shown in FIG. 3B, a concave portion is formed at the center of the upper surface or the lower surface of the first sealing resin body 16.
182 may be formed, or the projecting strip 18 and the groove 181 may be formed in combination as shown in FIG.

The protruding strip 18, groove 181 and recess 182 formed in this way are formed when the first sealing resin body 16 is integrally molded. The fixing means can be set on the surface of the first sealing resin body 16 by an adhesive or the like. For example, as shown in FIG.
An adhesive 183 is applied to the surface of the sealing resin body 16 of
Thereby, the adhesion between the first sealing resin body 16 and the second sealing resin body 17 is improved. Also, as shown in FIG. 8E, a process for forming irregularities 184 is performed on the surface of the first sealing resin body 16, and the second sealing resin body 17 is formed by the irregularities 184 on the surface of the first sealing resin body 16. It may be made to adhere effectively to.

When the second sealing resin body 17 is formed of a thermoplastic resin, generally for the purpose of improving the strength of the resin itself,
A filler such as glass fiber is mixed. The filler is oriented along the flow of the resin at the time of molding, and therefore, a phenomenon appears in which the linear expansion coefficient differs between the flow direction (orientation direction) of the resin and the direction perpendicular thereto.

Here, assuming that the linear expansion coefficient in the orientation direction is α211 and the linear expansion coefficient in the direction perpendicular to this is α21, if the combination of “α211 <α1” and “α21 <α1” is satisfied, the linear expansion coefficient shown in FIG. The effect is exhibited by the structure of the first embodiment. However, in the case of the combination of “α211 <α1” and “α21> α1”, as shown in FIG. 7, by making the cross-sectional area A1 of the plane perpendicular to the orientation direction smaller than the cross-sectional area A11 of the orientation direction, The goal can be achieved.

In this figure, the thermal stress generated at α21 and A1 is σb
And the thermal stress generated at α211 and A11 is σc, which is smaller than the thermal stress σa generated in the conventional structure.

Here, σa, σb, and σc are respectively expressed by the following equations.

The cross-sectional area A1 in the direction perpendicular to the orientation direction is calculated as the cross-sectional area in the orientation direction.
K times of A11 , The thermal stress can be reduced as compared with the conventional case.

FIGS. 8 to 13 show embodiments taking such points into consideration. In the embodiment shown in FIG. 8, at least the upper surface or the lower surface of the second sealing resin body 17 is shown. A recess 40 is formed in the groove, and the cross-sectional area A11 in the alignment direction is made larger than the cross-sectional area A1 perpendicular to the alignment direction. Here, in each figure (D), the directionality of the linear expansion coefficient is shown, and the length of the arrow indicates the magnitude of the absolute value.

In FIG. 9, an opening 41 is formed in one direction of the second sealing resin body 16 so as to release the thermal stress generated by the linear expansion coefficient α21 in the direction perpendicular to the orientation direction. FIG. 10 shows a configuration in which at least one slit 42 is formed along the orientation direction of the second sealing resin body 17, and the thermal stress generated by the linear expansion coefficient α21 in the direction perpendicular to the orientation direction is shown. Open to the public.

In the example shown in FIG. 11, an open portion 43 is formed by combining the examples shown in FIGS. 8 and 9. FIG. 12 shows a second sealing resin body 17 in which a slit-shaped opening 44 obtained by combining the example shown in FIG. 8 and the example shown in FIG. 11 is formed.

In the example shown in FIG. 13, at least one protrusion 45 is formed on at least the upper surface or the lower surface of the first sealing resin body 16 in a direction perpendicular to the alignment direction, and in the alignment direction. The anchor effect is activated so that the anchor effect does not act in a direction perpendicular to the orientation direction. The projection 45 may be a groove.

Although various modified examples have been described above, it is needless to say that the present invention is not limited to the examples shown here, and at least one of the second sealing resin bodies 17 may be used.
By making the coefficient of linear expansion in one specific direction (such as the orientation direction) smaller than the coefficient of linear expansion of the first sealing resin body 16, it is possible to reliably prevent the semiconductor element 11 from being damaged. The structures of the grooves, projections, and the like formed to enhance the effect can be configured by variously combining the examples shown so far. If the coefficient of linear expansion is anisotropic,
Furthermore, the structures shown in the embodiments can be appropriately combined.

[Effects of the Invention] As described above, according to the resin-sealed type semiconductor device of the present invention, the shape of the first sealing resin body is devised, and the shape and material of the second sealing resin body are changed. By devising,
The thermal stress generated between the main structure including the semiconductor element embedded therein and the first sealing resin body is reduced, and the reliability of the semiconductor device is effectively improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a resin-sealed semiconductor device according to one embodiment of the present invention, and FIGS.
Is a diagram showing the appearance of the first sealing resin body of this embodiment, FIG. 3 is a diagram showing a model for explaining thermal stress, and FIG. 4 is a diagram showing the state of thermal stress described in this model. FIG. 5, FIG. 5 shows a model of the semiconductor device shown in the embodiment, FIGS. 6A to 6E show examples of the cross-sectional structure of the semiconductor device, respectively, and FIG. FIGS. 8 to 13 show still another embodiment of the present invention, in which FIG. 8A to FIG. 13A show plan views, FIG. 8B and FIG. (C) is a sectional view taken along the line bb and cc of FIG.
(D) is a diagram showing the directionality of the linear expansion coefficient. 11 ... semiconductor element, 12 ... frame, 14 ... lead, 15
... bonding wire, 16 ... first sealing resin body, 17
... Second sealing resin body, 18... Protruding band, 181,.
82 ... recess, 183 ... adhesive, 184 ... unevenness, 40 ... recess, 41, 43, 44 ... open part, 42 ... slit.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keizo Funae 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside Denso Corporation (72) Inventor Koji Shibata 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nihon Denso Co., Ltd. (56) References JP-A-2-105471 (JP, A) JP-A-1-220465 (JP, A) JP-A-59-54944 (JP, U) JP-A-2-17850 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 23/30 H01L 23/28

Claims (4)

(57) [Claims] 1. A first sealing resin body for integrally sealing a main body constituting portion including a semiconductor element, a lead, and a bonding wire for connecting them, and an outer periphery of the first sealing resin body. A second sealing resin body formed so as to cover at least a part of the portion, wherein the fiber of the second sealing resin body is larger than the linear expansion coefficient of the first sealing resin body. The first and second linear expansion coefficients in a specified direction corresponding to the arrangement direction of the qualities are reduced.
Wherein the cross-sectional area of the second sealing resin body in a direction perpendicular to the specified direction is larger than the cross-sectional area of the second sealing resin body in the specified direction. A resin-encapsulated semiconductor device in which is set large. 2. A first sealing resin body for integrally sealing a main body constituting portion including a semiconductor element, a lead, and a bonding wire for connecting the both, and an outer periphery of the first sealing resin body. A second sealing resin body formed so as to cover at least a part of the portion, wherein the fiber of the second sealing resin body is larger than the linear expansion coefficient of the first sealing resin body. The first and second linear expansion coefficients in a specified direction corresponding to the arrangement direction of the qualities are reduced.
Wherein the first sealing resin is provided in at least one of the second sealing resin body in a direction perpendicular to the specified direction. A resin-encapsulated semiconductor device in which an opening through which a body is exposed is formed. 3. A first sealing resin body for integrally sealing a main body constituting portion including a semiconductor element, a lead, and a bonding wire for connecting them, and an outer periphery of the first sealing resin body. A second sealing resin body formed so as to cover at least a part of the portion, wherein the fiber of the second sealing resin body is larger than the linear expansion coefficient of the first sealing resin body. The first and second linear expansion coefficients in a specified direction corresponding to the arrangement direction of the qualities are reduced.
In the resin-sealed semiconductor device wherein the sealing resin body is selected, a groove in which the first sealing resin body is exposed along the specified direction of the second sealing resin body Forming the second
A resin-encapsulated semiconductor device wherein the encapsulating resin body is divided into two by the groove. 4. A first sealing resin body for integrally sealing a main body constituting portion including a semiconductor element, a lead, and a bonding wire for connecting both of them, and an outer periphery of the first sealing resin body. A second sealing resin body formed so as to cover at least a part of the portion, wherein the fiber of the second sealing resin body is larger than the linear expansion coefficient of the first sealing resin body. The first and second linear expansion coefficients in a specified direction corresponding to the arrangement direction of the qualities are reduced.
In the resin-encapsulated semiconductor device in which the encapsulation resin body is selected, the uneven shape formed on the first resin-encapsulation body extends in a direction perpendicular to the specified direction. A resin-encapsulated semiconductor device formed on a substrate.