JPH0628268B2 - Die bonding method for semiconductor pellets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a semiconductor pellet 3 and a gold foil at a predetermined position of a lead frame such as an island portion 2 formed on a lead frame 1 as shown in FIG. Alternatively, the present invention relates to a method of die bonding using a preform foil piece made of a metal foil such as a solder foil.

[Conventional technology]

The semiconductor pellet 3 having the width dimension (S) and the length dimension (L) is formed on the upper surface of the island portion 2 having the width dimension (T) and the length dimension (X) formed on the lead frame 1 as described above. In the conventional die bonding, as shown in FIGS. 4 and 5, the width dimension (W) narrower than the width dimension (S) of the semiconductor pellet 3 by 2 A is conventionally used.
A preform foil piece 4 having a length dimension (L) substantially equal to the length dimension (L) of the semiconductor pellet 3 is cut from the material tape for preform foil piece formed in 1. The semiconductor pellet 3 is interposed between the island portion 2 and the preform foil piece 4 is heated and melted, while pressing the semiconductor pellet 3 against the island portion 2 with an appropriate pressure. The position of the one-dot chain line separated from the position of the solid line to the right in the width direction by the distance (A) and the position of the chain double-dashed position separated from the position of the solid line to the left by the distance (A) in the width direction. The die bonding is performed by reciprocating the space a plurality of times.

Such an operation of reciprocating in the width direction while pressing the semiconductor pellet 3 against the island portion 2 is called scrubbing. By extending the preform foil piece 4 to the full width of the semiconductor pellet 3, the island portion 2 in the lead frame 1 is
On the other hand, the purpose is to weld the semiconductor pellet 3 over the entire surface.

Therefore, the width dimension (W) of the preform foil piece 4 is a value obtained by subtracting the stroke (2A) of the reciprocating motion in the scrub from the width dimension (S) of the semiconductor pellet 3, that is, S-2.
It is set to A = W.

[Problems to be solved by the invention]

In this die bonding, reducing the amount of the preform foil pieces 4 used can contribute to cost reduction. Therefore, if the width dimension (W) of the preform foil piece 4 is narrowed, the stroke (2A) when the semiconductor pellet 3 reciprocates in the scrubbing.
Will have to be increased.

However, increasing the stroke (2A) of the reciprocating motion in the scrub in this way not only causes an increase in the time required for the scrub, but also as described above, the semiconductor pellet 3 is die-bonded to the island portion 2. In some cases, the reciprocating stroke of scrub (2
A) should not exceed the size obtained by subtracting the width dimension (S) of the semiconductor pellet 3 from the width dimension (T) of the island portion 2, that is, T-S> 2A (stroke 2A is T- If it exceeds S, the semiconductor pellet 3 reciprocates over the width of the island portion 2, so that the preform foil piece 4 in the molten state is
Therefore, there is a problem in that the stroke of the reciprocating motion in the scrub is increased, and accordingly, the width dimension (W) of the preform foil piece 4 is reduced by a certain limit value. It existed.

An object of the present invention is to make it possible to reduce the amount of preform foil pieces used without increasing the stroke of reciprocation in scrubbing.

[Means for solving problems]

To achieve this object, the present invention, on the upper surface of a predetermined portion of the lead frame, a preform foil piece having a width narrower than the width of the semiconductor pellet is placed, and the semiconductor pellet placed on the piece is preformed with the preform foil. While pressing the piece against the lead frame in a state of being heated and melted, in the die bonding method adapted to reciprocate in the width direction, the preform foil piece is made into two thin preform foil pieces, The width dimension of both preform foil pieces is at least a dimension obtained by subtracting the stroke dimension of the reciprocating movement from the half of the width dimension of the semiconductor pellet, while the preform foil pieces are both the stroke dimension of the reciprocating movement. It is arranged so that they are arranged in parallel at substantially equal intervals.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3 of the drawings.

On the upper surface of the island portion 2 having the width dimension (T) and the length dimension (X), the semiconductor pellet 3 having the width dimension (S) and the length dimension (L) is formed.
When performing die bonding using the preform foil pieces, two preform foil pieces 4a are used as the preform foil pieces, and the width dimension (Wa) of both the preform foil pieces 4a is calculated as follows. A size obtained by subtracting the reciprocating stroke (2A) in the scrub from the half of the width dimension (S) of the pellet 3 is set to a narrow width of Wa = S / 2-2A, and both the preform foil pieces 4a are Island part 2
On the upper surface of the above, the preform foil pieces 4a are placed side by side in parallel with each other at an interval equal to the reciprocating stroke (2A), and the semiconductor pellets 3 are placed thereon.

Then, in a state where both the preform foil pieces 4a are heated and melted, the semiconductor pellet 3 is pressed against the island portion 2 with an appropriate pressure, and the distance (A) from the position of the solid line in FIG. Only the position of the alternate long and short dash line on the right side,
A so-called scrubbing is performed in which reciprocation is performed between the position indicated by the solid line and the position indicated by the alternate long and two short dashes line to the left in the width direction by a distance (A).

By the scrubbing of the reciprocating stroke (2A), both of the preform foil pieces 4a are stretched in the left-right direction, but the width dimension (Wa) of the preform foil pieces 4a is set as described above. To Wa = S / 2-2A,
Moreover, by setting the interval between both the preform foil pieces 4a to be equal to the reciprocating stroke (2A) (2A),
Both preform foil pieces 4a are stretched to the left and right end portions 3a, 3b of the semiconductor pellet 3, and are stretched so that the preform foil pieces 4a are prosperous to each other between the preform foil pieces 4a. Therefore, the semiconductor pellet 3 can be welded to the island portion 2 over the entire surface of the semiconductor pellet 3.

In this case, the total area of both preform foil pieces 4a is Wa ×
L × 2, and the area of the preform foil piece is 2A × L larger than the area of the preform foil piece in the conventional case.
That is, since the area between the preform foil pieces 4a can be reduced, the amount of the preform foil pieces used can be reduced without increasing the stroke of reciprocation in scrubbing.

Then, when the width dimension (Wa) of both preform foil pieces 4a is Wa = S / 2-2A as described above and the distance between the quantity preform foil pieces 4a is 2A, the preform foil pieces are However, in practice, the width dimension (Wa) of both preform foil pieces 4a should have some margin.

〔The invention's effect〕

As described above, according to the present invention, two preform foil pieces to be inserted between the lead frame and the semiconductor pellet are provided, and the preform foil pieces are arranged at intervals in the width direction, so that when scrubbing in die bonding, Without increasing the reciprocating stroke, and eventually without increasing the time required for scrubbing, the amount of expensive preform material used can be reduced by the area of the interval between the preform foil pieces. This has the effect of significantly reducing the cost required for die bonding.

[Brief description of drawings]

1 is a plan view of a lead frame, FIG. 2 is an enlarged plan view showing the method of the first embodiment of the present invention, and FIG. 3 is a second view.
Fig. 4 is a sectional view taken along line III-III in Fig. 4, Fig. 4 is an enlarged plan view showing a conventional method, and Fig. 5 is a sectional view taken along line VV in Fig. 4. 1 ... Lead frame, 2 ... Island part, 3 ... Semiconductor pellet, 4a ... Preform foil piece.

Claims (1)

[Claims] 1. A preform foil piece having a width narrower than that of a semiconductor pellet is placed on an upper surface of a predetermined portion of a lead frame, and the semiconductor pellet placed on the piece is heated and melted. In the die bonding method in which the preform foil piece is made to reciprocate in the width direction while being pressed against the lead frame in the state, the preform foil piece is made into two preform foil pieces having a narrow width. The width dimension of at least half of the width dimension of the semiconductor pellet minus the stroke size of the reciprocating motion, while separating both preform foil pieces at intervals substantially equal to the stroke size of the reciprocating motion. A die-bonding method for semiconductor pellets, characterized in that they are arranged in parallel.