JP2868029B2 - Precision plane alignment mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision flat centering mechanism, and more particularly, to a semiconductor assembly device such as a TAB (tape automated bonding) or a flip chip of a fine pitch which requires high mounting accuracy. The present invention relates to a precision flat alignment mechanism used.

[0002]

2. Description of the Related Art FIG. 3 is a view showing a case of a TAB mounting of a face-down type in a semiconductor assembly.
(A) is a diagram showing a state before bonding, and (b) is a diagram showing a state after bonding. 1A, reference numeral 1 denotes a substrate provided with an electrode pattern 2, which is mounted on a stage 3. Reference numeral 4 denotes a bonding tool which presses and heats the TAB lead 6 joined to the chip 5 against the electrode pattern 2 to join the electrode pattern 2 and the lead 6 as shown in FIG.

[0003] Such a face-down type T
In the AB mounting, when the lead pitch of the TAB is 200 μm or a brazing material is used for the bonding portion, the reference surface when bonding the lead 6 to the electrode pattern 2 on the substrate side (the substrate side: the stage surface, the chip side: the tip of the bonding tool) The surfaces (2) and (3) are designed so that the assembling operation is performed by increasing the assembling accuracy when mechanically assembling them, and maintaining a fixed flat surface on both sides.

In this case, the flatness of both surfaces alone is important, and the assembling accuracy is important. At the time of bonding, the lead surface follows the bonding tool, but the substrate side has warpage of the members, so that the lower surface of the lead to be actually bonded and the electrode pattern surface of the substrate do not become the same plane (parallel plane).

However, when there is a brazing material at the joint,
Since the brazing material acts as a cushion, it can be apparently joined up to a certain level of planar collapse. Even when there is no brazing material at the joint, if the lead pitch is wide, TAB
Because the lead itself is thick and the number of leads is small,
It is possible to forcibly join with the pressure at the time of joining.

However, the TAB lead pitch is 100 μm
When there is no brazing material in the joint at the level or less, if the flatness of the level of 5 μm or less is not exerted in the entire joint at the time of pressurization, poor joining occurs due to insufficient wetting and contact with the tool piece. For this reason, planar alignment mechanisms as shown in FIGS. 4 and 5 have been devised and put to practical use.

FIG. 4 shows a state in which the stage is fixed and the bonding tool is movable, and FIG.
(B) is a figure which shows the joining operation state. This is (a)
As shown in the figure, the bonding tool 4 is floatingly supported by the support member 7, and as shown in FIG. 2B, the lead 6 of the semiconductor chip 5 is pressed and heated on the electrode pattern 2 on the substrate 1 placed on the stage 3. It is designed to be bonded. At this time, even if the substrate 1 is inclined, the bonding tool 4 can follow the inclination.

FIG. 5 shows a state in which the bonding tool side is fixed and the substrate side is movable. FIG.
(B) is a figure which shows the joining operation state. In this method, the substrate 1 placed on the stage 3 via the balls 8 is pulled from all sides by springs 9 and the bonding tool 4 connects the leads 6 of the semiconductor chip 5 to the electrode patterns 2 of the substrate 1 as shown in FIG. Is pressed and heated for bonding. At this time, even if the substrate 1 is inclined, since the substrate 1 is supported at one point by the ball 8, the substrate 1 can be freely inclined and can follow the tip surface of the bonding tool 4.

[0009]

In the planar alignment mechanism described above with reference to FIG. 4, the bonding tool 4 is heated by a pulse heating method, so that the heating portion has a mechanically complicated structure. In addition, since a centering mechanism is additionally provided, the maintenance is poor. Although high-precision positioning is performed before pressure bonding, when the tool descends and one point of the TAB lead comes into contact with the substrate-side electrode pattern (one of both ends of each side of the chip), the bonding tool It rotates in the horizontal plane. For this reason, there are problems such as poor mounting accuracy.

In the flat centering mechanism described with reference to FIG. 5, the bonding tool side has a mechanically simple structure, but the substrate side concentrates the pressing load on one point of the ball, thereby increasing the strength. Problem. Furthermore, since the substrates are positioned only by the springs from four directions, reproducibility (positional) is not guaranteed even if the first substrate is pressed and joined and then the next substrate is set at the same position. There's a problem.

An object of the present invention is to realize a precision flat centering mechanism capable of improving the mounting accuracy when a semiconductor chip is mounted on a substrate using a semiconductor assembling apparatus.

[0012]

In the precision flat centering mechanism according to the present invention, a functional spring 15 for supporting a member receiving a pressing force, and a functional spring located at the center of the functional spring 15 are provided. Fifteen
And a column 16 having a slightly lower height and a spherical end.

In addition, the functional spring 15
Is characterized in that a cylinder made of an elastic material is provided with a plurality of steps in which cuts 17, 17 'are formed from the left and right of the outer periphery, and the cut directions of adjacent steps are different by 90 °. By employing this configuration, it is possible to obtain a precision planar alignment mechanism that can be used in a semiconductor assembly device and can improve the mounting accuracy when mounting a semiconductor chip on a substrate.

[0014]

[Function] Unlike the coil spring, the functional spring 15 is axially symmetric in shape, so that even when compressed by a load, the pressed surface does not rotate. Therefore, when used in semiconductor assembly equipment,
Even if the parallelism between the bonding tool surface and the electrode pattern surface is incorrect, the bonding tool side is lowered and leads 12
When one point a contacts the electrode pattern 13a, the functional spring portion immediately below that portion is compressed and the substrate 13 descends following the bonding tool 10.

Further, after the bonding tool 10 is lowered and the leads 12a come into contact with all of the electrode patterns on the substrate, the pressing force on the bonding tool side can be received by the rigid support 16.

[0016]

1 is a view showing a case where the embodiment of the present invention is used in a semiconductor assembling apparatus. FIG. 1 (a) is a sectional view, and FIG. 1 (b) is a perspective view showing a functional spring. 1A, reference numeral 10 denotes a bonding tool, and reference numeral 11 denotes a precision flat centering mechanism of the present embodiment.

The precision planar alignment mechanism 11 includes a semiconductor chip 12
A stage (a member receiving a pressing force) 14 for supporting a substrate 13 on which is mounted, a functional spring 15 for supporting the stage 14,
And a rigid support 16 located at the center of the functional spring 15.

The functional spring 15 is cut into a cylinder made of an elastic material as shown in FIG. 2B so that a connection portion 15a of a predetermined width remains from the left and right of the outer periphery.
A plurality of steps 17 and 17 'are provided, and the cutting directions of adjacent steps are different by 90 °. Also, the height of the support 16 is slightly lower than the height of the functional spring 15,
And the tip is spherical. The spring constant of the functional spring 15 can be designed to an arbitrary value by changing the material of the cylinder, the inner and outer diameters, and the thickness t between the cuts.

In the present embodiment configured as above, the substrate 13 is placed on the stage 14 as shown in FIG. 2, and the leads 12a of the semiconductor chip 12 are superimposed on the electrode patterns 13a on the substrate 13, The two parts can be joined by pressing the part with the bonding tool 10 and heating at the same time.

At this time, even if the parallelism between the bonding tool surface and the electrode pattern surface of the substrate is out of order, if the bonding tool side is lowered and one point of the lead 12a comes into contact with the electrode 13a, the functionality just below that part is obtained. The spring portion receives the compressive force, and the substrate 13 descends following the bonding tool.
Further, after the bonding tool is lowered and the leads 12a come into contact with all the electrode patterns 13a on the substrate, the stage 14 comes into contact with the columns 16, and the pressure is received by the columns 16 to complete the bonding. The distance ΔH between the support 16 and the stage 14 (see FIG. 1) depends on the bonding tool surface 10 and the substrate surface.
It suffices to have only 1/2 + α of the height difference due to the inclination of 13. After pressurization, the substrate 13 returns to its original position due to the reproducibility of the functional spring 15.

According to the above embodiment, when used in a semiconductor assembling apparatus, the bonding tool can be controlled by controlling the spring constant of the functional spring 15 (to make it as weak as possible).
The impact force when the 10 comes into contact with the substrate 13 can be avoided and the quality is stabilized. (If a shocking force is applied, only the lead in that portion will be crushed.) In addition, the descending speed on the bonding tool side can be increased, and the index can be shortened. Since the leads are evenly pressed, unevenness in pressurization and insufficient wetting are reduced, and the quality is stabilized. Since there is no rotation displacement in the horizontal plane, mounting accuracy is improved.

[0022]

According to the present invention, the use of the functional spring and the column disposed at the center thereof enables precise plane alignment such that the surface receiving the pressing force does not rotate in the horizontal plane. There is an effect that a semiconductor device of stable quality can be obtained by using the semiconductor assembly device.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a case where an embodiment of the present invention is used in a semiconductor assembling apparatus. FIG. 1A is a sectional view, and FIG. 1B is a perspective view showing a functional spring.

FIG. 2 is a diagram for explaining the operation of the embodiment of the present invention.

3A and 3B are diagrams showing a conventional face-down type TAB mounting, in which FIG. 3A shows a state before bonding,
(B) is a figure which shows the state after bonding.

FIG. 4 is a diagram showing a conventional planar alignment mechanism.

FIG. 5 is a view showing a conventional planar alignment mechanism.

[Explanation of symbols]

 10 Bonding tool 11 Precision plane alignment mechanism 12 Semiconductor chip 12a Lead 13 Substrate 13a Electrode pattern 14 Stage 15 Functional spring 16 Post 17, 17 'Cut 18 Connection

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-218140 (JP, A) JP-A-4-291936 (JP, A) JP-A-4-94551 (JP, A) JP-A-4,945 29341 (JP, A) JP-A-63-229727 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/60 311 H01L 21/52

Claims (2)

(57) [Claims] 1. A functional spring (15) for supporting a member that receives a pressing force, and a center located at the center of the functional spring (15), a height slightly lower than the functional spring (15), and A precision flat centering mechanism comprising a support (16) having a spherical end. 2. The functional spring (15) is formed by cutting a cylinder formed of a material having elasticity from the left and right of the outer periphery thereof.
2. The precision flat centering mechanism according to claim 1, wherein a plurality of steps including (17, 17 ') are provided, and the cutting directions of adjacent steps are different by 90 °.