JPH03218035A - Semiconductor element mounting board - Google Patents

Abstract

PURPOSE:To reduce the time and the cost necessary for mounting by forming, on a board surface, recessed parts becoming gradually deep from the periphery toward the center part and accepting at least the tip parts of bumps on a semiconductor element. CONSTITUTION:A plurality of bumps 2 are formed on a semiconductor element 1 so as to protrude from the surface. On a board 3 on which the element 1 is mounted, a plurality of electrode terminals 5 are formed so as to correspond with the bumps 2. An electrode terminal 5 is formed at the center part of the recessed part 4, which is formed so as to have a size capable of accepting at least the tip part of the bump 2. The recessed part 4 is formed so as to become deep gradually from the outer periphery toward the center part where the terminal 5 is formed. The recessed part 4 is formed so as to become deep gradually by a step-wise or smooth surface. Hence the bumps 2 can be accurately aligned with the terminals 5 only by pushing the element 1 on the board 3 after rough alignment, so that the time and the cost necessary for mounting can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor element mounting substrate on which a semiconductor element such as an IC chip is mounted.

[Conventional technology]

When mounting a semiconductor element such as an IC on a substrate, a convex bump is formed on the electrode pad of the semiconductor element, and this bump is directly connected to the electrode terminal formed on the substrate. ing.

[Problem to be solved by the invention]

Conventionally, electrode terminals on a substrate have been formed flat. For this reason, unless the bumps on the semiconductor element are accurately aligned with the electrode terminals on the substrate, there is a risk that the bump material will protrude to the periphery of the electrode terminals, causing a short circuit between adjacent electrode terminals.

Furthermore, the higher the degree of integration of semiconductor elements, the smaller the size and pitch of the electrode terminals formed on the substrate. Therefore, as the degree of integration increases, it becomes necessary to align bumps and electrode terminals with extremely high precision.

However, alignment with such high precision requires a certain amount of time, increases the time required for implementation, and requires a highly accurate and expensive alignment device. For this reason, the implementation cost has been high.

Therefore, in view of the above-mentioned circumstances, the present invention aims to shorten the time required for implementation and reduce the implementation cost.

[Means to solve the problem]

In order to achieve the above object, in the substrate for mounting a semiconductor element according to the present invention, a recess is formed on the surface of the substrate, the recess gradually deepening from the outer periphery toward the center and receiving at least the top of the bump on the semiconductor element. An electrode terminal connected to the bump is formed in the center of the recess.

[Effect]

By doing so, the bumps on the semiconductor element can be accurately aligned with the electrode terminals on the substrate simply by pressing the semiconductor element against the substrate after rough alignment.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows a substrate for mounting a semiconductor element according to the present invention and a semiconductor element roughly aligned with its electrode terminals, and FIG. 2 shows the state after mounting.

As shown in the figure, a plurality of bumps 2 are formed on the semiconductor element 1 so as to protrude from the surface thereof.

On the other hand, a plurality of recesses 4 are formed in the substrate 3 on which the semiconductor element 1 is mounted, corresponding to the bumps on the semiconductor element 1, and an electrode terminal 5 is formed in the center of the recess 4. The recess 4 is formed in a size large enough to receive at least the top (lower end in the figure) of the bump 2 formed on the semiconductor element 1, and extends from the outer periphery toward the center where the electrode terminal 5 is formed. It is formed so that it gradually becomes deeper. In addition, as shown in the figure, the recess 4 may be gradually deepened in a step-like manner, or may be a smooth surface that gradually becomes deeper from the outer periphery to the center.

The electrode terminal 5 is formed, for example, by selectively plating the center of the recess 4.

When mounting the semiconductor element 1 on the substrate 3 in which the recess 4 and the electrode terminal 5 are formed in this way, the bumps 2 on the semiconductor element 1 and the electrode terminal 5 on the substrate 3 are aligned at a position not shown. This alignment is carried out by an alignment device, but as shown in FIG. 1, rough alignment is sufficient to prevent the top of the bump 2 from protruding into the recess 4. This is because if the top of the bump 2 is aligned within the range that fits within the recess 4, then after this alignment the semiconductor element 1
By lightly pressing the bump 2 against the substrate 3, the bump 2 is guided by the surface of the recess 4 and automatically moves to the center of the recess 4 where the electrode terminal 5 is formed, as shown in FIG. This is because the bump 2 and the electrode terminal 5 are accurately aligned with each other.

After accurate alignment is performed in this way, the substrate 3 is heated to melt the bumps 2, and the bumps 2 and the electrode terminals 5 are connected to each other. In this way, when the bumps 2 are melted, the surface tension of the melted bump material is applied to the electrode pads (not shown) on the semiconductor element 1 on which the bumps 2 are formed.
and the electrode terminal 5 on the substrate 3, the surface area of the bump material is reduced as much as possible. Therefore, this surface tension acts in a direction that minimizes the overall positional deviation between each electrode pad on the semiconductor element 1 on which the bump 2 is formed and each electrode terminal 5 on the substrate 3, and
are guided to a position where the surface tensions of each bump material balance each other. In other words, this surface tension automatically achieves even more accurate alignment.

Note that instead of melting the bumps 2, an insulating adhesive that shrinks when cured is filled between the semiconductor element 1 and the substrate 3, and the bumps 2 are pressed against the electrode terminals 5 by the curing shrinkage force of the adhesive. 2 and the electrode terminal 5 may be electrically connected to each other.

The size of the bump 2 formed on the semiconductor element 1 is 8 in diameter.
The semiconductor element 1 was mounted on the substrate 3 with a height of 0 μm and a height of about 30 μm, and an electrode terminal 5 formed in the center of the recess 4 formed in the substrate 3 with a diameter of 100 μm. In this case, in order to keep the positional deviation between the bump 2 and the electrode terminal 5 after mounting within ±10 μm, the alignment accuracy required of the alignment device is approximately the outer radius of the recess 4 formed on the substrate 3 (± 50 μm or more). On the other hand, when the same semiconductor element as in the above example was mounted on a conventional substrate on which flat electrode terminals with the same dimensions as in the above example were formed, the accuracy required for the alignment device was ±10 μm.
Met. The results are shown in the table below.

〔Effect of the invention〕

As described above, according to the present invention, a relatively inexpensive alignment device can be used instead of requiring a highly accurate and expensive alignment device as in the prior art.

Furthermore, since only rough alignment is required by the alignment device, the time required for alignment by the alignment device is shorter than in the past, which required precise alignment by the alignment device.

Therefore, the time and cost required for implementation can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a substrate for mounting a semiconductor element according to the present invention and a semiconductor element roughly aligned with its electrode terminal, and FIG. 2 is a diagram showing the state after mounting them. 1... Semiconductor element, 2... Bump, 3... Substrate,
4... Recessed portion, 5... Electrode terminal.

Claims (1)

[Scope of Claims] A substrate on which a semiconductor element having bumps on the surface is mounted, wherein a recess is formed in the surface, the recess deepening from the outer periphery toward the center and receiving at least the top of the bump. A substrate for mounting a semiconductor element, wherein an electrode terminal connected to the bump is formed in the center of the recess.