JPH11163197A - Semiconductor mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor mounting board which can be mounted on a motherboard, improved in electrical reliability, and improved in connection reliability when it is mounted on the motherboard. SOLUTION: A recess 11 is provided to the rear center of an insulating board 10. An edge electrode 13 is provided to each edge face of the insulating board 10 spreading in the thickness direction of the board 10, surface circuits 14 each connected to the edge electrodes 13 are provided to the surface of the board 10 extending from the edges toward center of the board 10, and back electrodes 15 each of which connected to the edge electrodes 13 are formed on the rear of the board 10. A resist 5 is provided to the surface of the insulating board 10 for covering the surface of the surface circuits 14 with the center and edges of the board 10 left exposed. The length A of an exposed part between the end of the resist 5 and the edge of the board 10 is set larger than a length B of the back electrode 15, which extends from the edge of the board to its other edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor mounting substrate used for mounting a semiconductor element such as an IC chip, and more particularly, to mounting a plurality of semiconductor elements mounted on a motherboard in a state where the semiconductor elements are mounted. The present invention relates to a semiconductor mounting substrate that can be used.

[0002]

2. Description of the Related Art Conventionally, various types of packages have been widely used as a semiconductor mounting substrate for mounting a semiconductor element such as an IC chip, sealing it with a resin, and mounting it on a motherboard for use. I have. As one type, an LCC (leadless chip) having a configuration in which an end surface electrode exposed to the outside is provided on the peripheral end surface of the substrate, and conduction with a circuit on a motherboard is achieved through the end surface electrode.
carrier) (QFN (quad flat)
Packages (also referred to as non-leaded packages) are known.

[0003]

In recent years, with the increase in the density of electronic components mounted on a motherboard,
Demand for high integration of semiconductors is increasing.

[0004] In order to meet such demands, the applicant of the present application has paid attention to an LCC whose package itself is relatively easy to handle and has high mounting reliability.
In the invention described in Japanese Patent Application No. Hei 9-157189 (hereinafter referred to as the prior invention) filed on Nov. 5, the present invention proposes a semiconductor mounting substrate (LCC) capable of high integration. It was made with the prior invention as an opportunity.

It is a major object of the present invention to provide a package for mounting a semiconductor element, which is a package for mounting a semiconductor element, which can be mounted on a motherboard and mounted thereon, similarly to the above-mentioned prior invention. It is still another object of the present invention to provide a semiconductor mounting substrate which has improved electrical reliability and improved connection reliability when mounted and mounted on a motherboard in addition to the above objects.

[0006]

A semiconductor mounting substrate according to the present invention has the following essential components to achieve the above object. That is, an insulating substrate having opposite front and back surfaces is provided, and a concave portion is formed at the center of the back surface of the insulating substrate. In this insulating substrate, an end surface electrode exposed to the outside is formed on the peripheral end surface so as to straddle in the thickness direction of the substrate, and a surface circuit extending on the surface from the edge portion of the substrate toward the center portion in conduction with the end surface electrode. On the other hand, on the back surface, a back surface electrode communicating with the end surface circuit is formed. Further, a resist is provided on the surface of the insulating substrate, and the surface of the surface circuit is covered with the resist except for portions of the surface circuit on the substrate center side and the substrate end side as exposed portions. Of the exposed portions of the surface circuit, the exposed portion on the center side of the substrate is used as a semiconductor connection electrode for connecting to a semiconductor element, and the end portion of the substrate surface is mounted with the semiconductor mounting substrate mounted thereon. It is sometimes used as an upper mounting electrode for connecting to a back surface electrode of a semiconductor mounting substrate mounted on an upper layer. The dimension of the upper stacking electrode from the edge of the resist to the edge of the substrate is larger than the dimension of the back electrode from the edge of the substrate to the edge of the center of the substrate.

In the semiconductor mounting substrate, there are two methods for mounting a semiconductor element, as described below, by mounting the semiconductor element in the recess or in the center of the substrate surface. When a semiconductor element is mounted in the recess, it is preferable to form a through hole that opens in the insulating substrate at the bottom of the recess and at the center of the surface of the substrate. One main surface of the semiconductor element to be mounted is fixed to the bottom of the recess. Preferably, the semiconductor element and the semiconductor connection electrode on the substrate surface are connected and connected through the through hole. On the other hand, when the semiconductor element is mounted at the center of the surface of the insulating substrate, a portion for mounting the semiconductor element is provided at the center of the surface of the insulating substrate, and the center of the surface circuit is provided near the periphery of the portion. In this case, it is preferable to place a semiconductor element in the center of the surface of the insulating substrate and to connect and connect the semiconductor element and the electrode for semiconductor connection on the surface of the substrate.

The semiconductor mounting board on which the semiconductor elements are mounted as described above is placed at a predetermined position on the motherboard, and the end face electrodes are soldered in accordance with the circuit formed on the motherboard. It is mounted on a motherboard, and can be stacked in a plurality as follows. That is, the upper semiconductor mounting substrate is mounted on the lower semiconductor mounting substrate mounted on the motherboard, and the lower electrode of the upper semiconductor mounting substrate is placed on the upper mounting electrode of the lower semiconductor mounting substrate. By connecting them by soldering, vertical conduction is achieved and the upper semiconductor mounting substrate is fixed. At this time, in the semiconductor mounting substrate of the present invention, since the concave portion plays a role of accommodating the semiconductor element mounted on the semiconductor mounting substrate, the semiconductor mounting substrate can be easily stacked vertically. For example, in the above two mounting methods of the semiconductor element, for example, when the semiconductor element is mounted in the concave portion of the semiconductor mounting substrate, the semiconductor element does not protrude from the semiconductor mounting substrate. When the semiconductor element is mounted on the center of the surface of the semiconductor mounting board, the semiconductor element mounted on the lower semiconductor mounting board is placed in the recess of the upper semiconductor mounting board. The semiconductor mounting substrate can be vertically stacked.

In the semiconductor mounting substrate according to the present invention, the resist provided on the surface of the insulating substrate serves to protect a surface circuit, and high electrical reliability is obtained. The short circuit of the surface circuit due to the solder bridge or the like at the time of the connection connection with the above can be prevented. Further, in the present invention, in order to enable good vertical conduction during vertical mounting of the semiconductor mounting substrate, an exposed portion of the surface circuit on the side of the substrate end which is not covered with the resist, that is, the upper mounting electrode Wherein the dimension from the edge of the resist to the edge of the substrate is larger than the dimension of the back electrode from the edge of the substrate to the edge of the substrate on the center side. Thus, when the semiconductor mounting substrate is vertically stacked, the resist layer is not interposed between the upper mounting electrode of the lower semiconductor mounting substrate and the back surface electrode of the upper semiconductor mounting substrate. Therefore, good soldering can be performed with a relatively small amount of solder. That is, when the resist layer is interposed between the back electrode and the upper stacking electrode to be solder-bonded, a gap is generated between the upper and lower electrodes by the thickness of the resist. If the amount is small, the gap cannot be filled and connection failure or bonding failure may occur.On the contrary, if the amount of solder is increased and the solder bonding layer is made thicker than the gap, bonding and connection of the upper and lower electrodes can be performed, Although there is a possibility that the solder flows to an unnecessary place to cause a short circuit between the adjacent surface circuits or the end face electrodes due to a solder bridge, the semiconductor mounting substrate of the present invention does not have such a concern.

In the present invention, an exposure dimension from an end of the resist to an edge of the substrate in the upper stacking electrode;
The difference between the dimension of the back electrode from the edge of the substrate to the edge of the center of the substrate is preferably in the range of 100 to 200 μm. By setting the dimensional difference between the upper mounting electrode and the back electrode in such a range, the upper mounting exposed from the resist can be taken into account even when a positioning error such as exposure during pattern formation of the resist is considered. Since the length of the electrode for use does not become longer than the length of the back electrode, the size of the upper mounting electrode can be minimized, and the surface circuit can be sufficiently covered to ensure high electrical reliability. it can.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing a semiconductor mounting substrate 1 according to one embodiment of the present invention. Semiconductor mounting board 1
Is provided with a rectangular insulating substrate 10 having front and rear surfaces facing each other, and a rectangular concave portion 11 is formed at the center of the rear surface of the insulating substrate 10. The size of the opening of the recess 10 is larger than the outer dimension of the semiconductor element 2 (to be described later) to be mounted, and the depth of the recess 11 is larger than the thickness of the semiconductor element 2.

In the insulating substrate 10, a rectangular through hole 12 having a smaller opening area than the opening of the recess 11 is formed at the center of the bottom surface of the recess 11 and at the center of the substrate surface. The size of the through hole 12 is smaller than the size of the semiconductor element 2 to be mounted.

As shown in FIG. 2, a plurality of depressions extending in the thickness direction of the substrate are formed on the peripheral end surface of the insulating substrate 10, and the end surface electrodes 1 exposed to the outside are formed on the inner surfaces of the depressions.
3 is formed so as to straddle in the thickness direction of the substrate. The surface of the insulating substrate 10 is electrically connected to the end face electrode 13 and is electrically connected to the edge of the substrate. Is formed. On the other hand, on the back surface of the insulating substrate 10, a plurality of back surface electrodes 15 communicating with the end surface circuits 13 are formed so as to surround the periphery of the opening of the concave portion 11 corresponding to each end surface electrode 13. These electrodes and circuits are usually formed of copper, and if desired, a nickel film, a gold film, and the like can be appropriately formed thereon by a plating method or the like.

A resist 5 is provided on the surface of the insulating substrate 13 to serve as a plating resist or a solder resist. As the resist 5, a photoresist, a thermosetting resist, or the like can be used. The resist 5 is formed by leaving the portions of the surface circuit 14 on the substrate center side and the substrate end side as exposed portions.
Is covered. Here, of the exposed portions of the surface circuit 14, the exposed portion on the center side of the substrate is a semiconductor for connecting to the semiconductor element 2 when the semiconductor element 2 is mounted on the semiconductor mounting substrate 1 as shown in FIG. The connection electrode 14b serves as an upper mounting portion for connecting to the back surface electrode of the semiconductor mounting substrate 1 placed on the upper side when the semiconductor mounting substrate 1 is mounted and mounted as shown in FIG. Electrode 14a. The dimension A of the upper stacking electrode 14a from the edge of the resist 5 to the substrate edge is larger than the dimension B of the back electrode 15 from the substrate edge to the substrate center end. At this time, resist 5
In order to ensure the above dimensional relationship even when considering the alignment error when forming the pattern of the resist 5 by exposure or the like, the size of the dimension A is 100 to 100 times larger than the size of the dimension B. It is preferable to make the length longer by 200 μm.

The manufacture of the semiconductor mounting substrate 1 can be performed, for example, by the following method. First, a mother substrate larger than at least the insulating substrate 13 is prepared, and a plurality of through holes are formed in the mother substrate at positions corresponding to the outer peripheral edges of the insulating substrate 13. Next, plating is applied to the inner peripheral surface of the through hole by a method such as electroless plating or electrolytic plating, and plating is applied to both the front and back surfaces of the mother substrate to form the front surface circuit 14 and the back surface electrode 15. Then, a resist 5 is applied to the surface of the mother substrate, and the resist 5 is cured by patterning so that the semiconductor connection electrode 14b and the upper mounting electrode 14a of the surface circuit 14 are exposed. At this time, the resist 5 may be formed by applying the resist 5 in a patterned form from the beginning and curing the resist 5 as it is, or after applying the resist 5 on the entire surface and curing it to a predetermined pattern, You may make it remove a part. Next, in the mother substrate, a concave portion 11 is formed at the center of the rear surface side at a position to be the insulating substrate 10 by spot facing or the like, and a through hole is formed from the bottom surface of the concave portion 11 to the substrate surface side. Then, the mother substrate is cut by a method such as die punching so that the through hole is cut into approximately half at a position corresponding to the outer peripheral edge of the insulating substrate 10, and the insulating substrate 10 is cut out. The semiconductor mounting substrate 1 is obtained. Note that the above-described manufacturing method is an example of manufacturing the semiconductor mounting substrate 1, and in the present invention, it is possible to appropriately change the execution procedure of the above steps, or to adopt a manufacturing method including completely different steps. It is possible.

FIG. 3 shows an example of mounting the semiconductor element 2 on the semiconductor mounting substrate 1. In this embodiment, the semiconductor element 2 is mounted on the semiconductor mounting substrate 1 as shown in FIG. First, the semiconductor element 2 has an outer dimension smaller than the opening dimension of the concave portion 11 and larger than the through hole 12 and a thickness smaller than the depth of the concave portion 11, and has an electrode pad 21 in a central portion of one main surface. Things are used.
The semiconductor element 2 has one main surface formed by an electrode pad 21.
Is fixed to the bottom surface of the concave portion 11 via the adhesive layer 3 so that the position of the electrode pad 21 coincides with the through hole 12, and the electrode pad 21 and the semiconductor connection electrode 14 b are connected by the bonding wire 4 through the through hole 12. Then, it is mounted in the recess 11 of the semiconductor mounting substrate 1. At this time, the bonding wire 4 is solder-bonded to the semiconductor connection electrode 14b.
Are provided, so that the adjacent semiconductor connection electrodes 14
Short circuit between b and 14b due to the solder bridge is prevented. Further, the semiconductor mounting substrate 1 on which the semiconductor element 2 is mounted as described above has at least a surface opening of the through hole 12 and the outer through hole 12 in order to seal at least a continuous portion by the bonding wire 4. The peripheral portion is resin-sealed by the sealing material 6.

FIG. 4 shows an example of mounting the semiconductor mounting substrate 1 on the motherboard 9, and FIG. 5 shows an example in which the semiconductor mounting substrate 1 is further mounted thereon and mounted.

As shown in FIG. 4, the semiconductor mounting substrate 1 on which the semiconductor element 2 is mounted is a motherboard 9 as shown in FIG.
On the motherboard 9.
It is mounted on the motherboard 9 by bonding with an electrode (not shown) provided thereon and using a solder 7.
Further, as shown in FIG. 5, another semiconductor mounting substrate 1 can be placed and stacked on the semiconductor mounting substrate 1 mounted on the motherboard 9. By bonding the back electrode 15 of the lower semiconductor device to the front electrode 14 of the lower semiconductor device, the upper semiconductor mounting substrate 1 is fixed and connected up and down. The portion of the sealing material 6 which has hardened and rises above the surface of the substrate is accommodated in the space below the semiconductor element 2 in the concave portion 11 of the upper semiconductor mounting substrate 1, so that such a stacked structure is possible. Has become.

In the semiconductor mounting substrate 1 of this embodiment, the relationship between the dimension A of the upper mounting electrode 14a and the dimension B of the back electrode 15 is A> B. , Upper mounting electrode 14a and back electrode 1
5 can be connected or joined well. In this regard, the electrodes 14a, 14a, shown in FIG.
A description will be given in comparison with an example (comparative example) of the mounting structure of the semiconductor mounting substrate 1 when the dimensional relationship of 15 is A <B. First, in the mounting structure of this comparative example, the upper mounting electrode 1 is mounted on the semiconductor mounting substrates 1 and 1 stacked vertically.
A layer of resist 5 is interposed between 4a and back electrode 15. In this case, a gap is generated between the upper and lower electrodes 14a and 15 by the thickness of the resist 5. These electrodes 14
When the solders a and 15 are solder-bonded, if the amount of the solder 8 used is small, the gap cannot be filled and a connection failure or a bonding failure may occur, so that the layer of the solder 8 is thicker than the gap. However, in this case, the solder 8
May flow to unnecessary places and cause a short circuit between the adjacent surface circuits 14 and 14 and between the end face electrodes 13 and 13 due to a solder bridge. On the other hand, in the semiconductor mounting substrate 1 according to the embodiment in which A> B, the semiconductor mounting substrate 1,
In the vertical stacking structure 1, the lower semiconductor mounting substrate 1
Can be soldered between the upper mounting electrode 14a and the back electrode 15 of the upper semiconductor mounting substrate 1 without the interposition of the resist 5 layer. Can be performed. Therefore, the disadvantages as in the comparative example are prevented in the semiconductor mounting substrate 1 of the embodiment.

[0021]

As described above, the substrate for mounting a semiconductor device according to the present invention can have a structure in which semiconductor elements mounted on the substrate for mounting a semiconductor device are stacked vertically while being accommodated in a recess. It is. In addition, the semiconductor mounting substrate of the present invention has high electrical reliability because the resist provided on the surface of the insulating substrate plays a role of protecting a surface circuit. The short circuit of the surface circuit due to the solder bridge or the like at the time of the connection connection can be prevented. Further, in the present invention, in the exposed portion on the substrate end side of the surface circuit that is not covered by the resist, that is, in the upper mounting electrode, the dimension from the edge of the resist to the substrate edge is from the substrate edge in the back electrode. Since the size is larger than the dimension up to the edge on the center side of the substrate, in the loading structure of the semiconductor mounting substrate, the upper loading electrode of the lower semiconductor mounting substrate and the lower electrode of the upper semiconductor mounting substrate Since these can be solder-bonded without interposing the above-mentioned resist layer between them, good solder bonding can be performed with a relatively small amount of solder, and as a result, poor connection or poor bonding is prevented, In addition, a short circuit due to a solder bridge between the surface circuits and between the end surface electrodes is prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor mounting substrate according to a first embodiment of the present invention.

FIG. 2 is a partial perspective view showing the substrate in a state where a resist is removed in the semiconductor mounting substrate of the embodiment.

FIG. 3 is a cross-sectional view showing a state where a semiconductor element is mounted on the semiconductor mounting substrate of the embodiment.

4 is a cross-sectional view showing a state where the semiconductor mounting substrate shown in FIG. 3 is mounted on a motherboard.

FIG. 5 is a cross-sectional view showing a state in which the semiconductor mounting substrate is further stacked and mounted on the semiconductor mounting substrate in the state shown in FIG. 4;

FIG. 6 is a cross-sectional view showing a stacked state of a semiconductor mounting substrate according to a comparative example for comparison with the state shown in FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 semiconductor mounting substrate 10 insulating substrate 11 concave portion 12 through hole 13 end surface electrode 14 surface circuit 14a upper mounting electrode 14b semiconductor connection electrode 15 back electrode 2 semiconductor element 5 resist 8 solder A size of upper mounting electrode B back electrode Size

Claims (2)

[Claims] 1. An insulating substrate having opposite front and back surfaces, a concave portion is formed at the center of the rear surface, and an end surface electrode exposed to the outside is formed on a peripheral end surface of the insulating substrate so as to straddle in the thickness direction of the substrate. Along with the front surface circuit of the insulating substrate, a front surface circuit extending from the edge portion of the substrate toward the center portion and a back surface electrode communicating with the end surface circuit are formed on the back surface of the insulating substrate. A resist is provided on the surface of the insulating substrate to cover the surface of the surface circuit, and exposed portions not covered by the resist are provided on the center and side edges of the substrate in the surface circuit to provide a semiconductor connection electrode and an upper stacking portion. An electrode is formed, and the dimension from the edge of the resist to the edge of the substrate in the upper stacking electrode is set at the center of the substrate from the edge of the substrate in the back electrode. A substrate for mounting a semiconductor, characterized in that it has a size larger than an end. 2. A difference between an exposed dimension of the upper stacking electrode from the edge of the resist to the edge of the substrate and a dimension of the back electrode from the edge of the substrate to the edge of the center of the substrate is 100 to 200 μm. The substrate for mounting a semiconductor according to claim 1, wherein: