JPS6142417B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wire bonder.

The XY table in a conventional wire bonder used for manufacturing semiconductor devices, etc. is driven by a pulse motor, a DC motor, etc., and is moved in a criss-cross direction by manual operation.

However, with this type of XY table, the travel time varies depending on the distance traveled, so
When moving the table diagonally, the moving times in the X and Y directions are different, and when the XY table moves, the movement will not be in a straight line but in a complicated curve. Therefore, although the bonding wire should normally be stretched in a straight line from the pad electrode to the lead, since the capillary moves in a meandering manner, the bonding wire is stretched while bending to the right or left, which causes defects in the shape of the bonding wire. It is becoming. Also, if the length of the bonding wire is different, the time it takes for the XY table to move from the pad electrode to the lead will be different, so the relationship between the vertical movement of the capillary and the travel of the XY table will be different depending on the length of the bonding wire. As a result, the shape of the bonding wire becomes different depending on its length, and the stability of the shape of the bonding wire is impaired.

Therefore, an object of the present invention is to provide a wire bonder that allows the XY table to run in a straight line, stabilizes the shape of the bonding wire, and prevents a decrease in device product yield due to bonding work.

In order to achieve such an object, in the present invention, the acceleration ratio and maximum speed ratio of the X table and Y table constituting the XY table are
It is controlled to be approximately equal to the ratio of distances to be moved in each direction.

Each table is driven, for example, by a DC motor, so that its moving speed V is controlled as shown in FIG. That is, from the start of movement until time t ₁ , it moves while accelerating at an acceleration α, and then moves at the maximum speed Vmax until time t ₂ , and at time t ₂
From then on, it moves while decelerating at the acceleration β and stops at time _t3 . In this case, the moving distance of the table is the area S surrounded by the above α, Vmax, β and the time axis T.
It is represented by.

According to the present invention, for example, the moving distance in the X direction
When Sx is long and the moving distance Sy in the Y direction is short, the moving speed Vx of the X table is controlled as shown in Figure 2, and the moving speed Vy of the Y table is controlled as shown in Figure 2.
The speed is controlled as shown in the figure. In other words, the acceleration ratio (αx/αy・βx/βy) and maximum speed ratio (Vxmax/Vymax) of both tables are respectively the moving distance ratio (
Sx/Sy). As a result, the speed ratio of both tables (Vx(t)/Vy(t)) at a certain time t is calculated by the following formula (1
) to (3), it is equal to the moving distance ratio (Sx/Sy=K) from the start of movement to the stop.

Vx(t)/Vy(t)=αx・t/αy・t=αx
/αy=Sx/Sy=K(0<t<t ₁ ) ......(1) Vx(t)/Vy(t)=Vxmax/Vymax=
Sx/Sy=K( _t1 <t< _t2 )...(2) Vx(t)/Vy(t)=βx・t/βy・t=βx
/βy=Sx/Sy=K(t ₂ <t<t ₃ ) ... (3) Therefore, the moving distance Sx (t) of the X table and the moving distance Sy (t) of the Y table at a certain time t.
The relationship expressed by the following equation (4) arises between .

Sx (t) =∫ ^t _p Vx (t) dt = ∫ ^t _p KVy (t) dt = K∫ ^t _p Vy (t) dt = KSy (t)... (4) In other words, the moving distance ratio of both tables is always constant from the start of movement to the stop (Sx(t)/Sy(t)=K
).

Therefore, movement in the diagonal direction by the XY table can be made into linear movement.

Therefore, the wire bonder of the present invention having such an XY table can straighten the bonding wire from the first bond to the second bond.

Hereinafter, in the wire bonder according to the present invention,
The speed control and positioning control of the XY table will be explained in detail with reference to the block diagrams shown in FIGS. 4 and 5.

FIG. 4 shows a block diagram of an embodiment for performing the above speed control in the X direction, and the symbols shown in the figure are as follows.

X ₀ : Maximum distance that the XY table moves in the X direction (maximum separation distance in the X direction between the pad electrode and lead) X ₁ : Distance that the XY table should move in the X direction (command movement distance) Vmax: Command movement distance Maximum travel speed in the X direction when X ₀ αmax: Acceleration in the X direction when the commanded travel distance is X ₀ βmax: Deceleration in the X direction when the commanded travel distance is X ₀ G (S): Received command speed V ₀ A control circuit for _{controlling the table} to this _speed . In this way, according to the above embodiment, _Vmax , α
max and βmax are converted into a commanded speed _V0 in proportion to the commanded movement distance _X1 , and the table is moved following this speed. By performing such control also in the Y direction, when the XY table is moved diagonally, the movement can be made in a straight line.
Acceleration/deceleration switching is performed using an electrical switching mechanism by setting a switching time in advance or by setting the switching time based on the ratio between X ₀ and the actual amount of movement.

On the other hand, the positioning control of the XY table is based on position feedback K because the speed control does not perform position feedback, so accurate positioning cannot be expected. This is done by switching to positioning.

In addition, if the drive motor has a fast response and starts and stops (acceleration/deceleration) quickly,
Approximate fixed-time control can be performed simply by controlling Vmax.

According to the wire bonder having an XY table that performs constant time control as described above, the bonding wire can be stretched in a straight line from the pad electrode (first bond) to the lead (second bond), and the bonding wire from the pad electrode can be stretched in a straight line. Since the wire enters directly from the front of the lead and can be bonded to the front of the lead without touching the side of the lead, the shape of the bonding wire is extremely good, which greatly improves manufacturing yield. .

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining fixed time control of the XY table in the wire bonder according to the present invention, FIG. 4 is a block diagram showing speed control, and FIG. 5 is a diagram showing positioning control. It is a block diagram.

Claims (1)

[Claims] 1 An X whose movement in the X direction and the Y direction is started and ended almost simultaneously, and which is controlled so that the acceleration ratio and the maximum speed ratio are approximately equal to the ratio of the distances to be moved in the X direction and the Y direction, respectively. It is equipped with a table and a Y table, and the first
A wire bonder characterized in that a bonding wire from a bond to a second bond is stretched in a substantially straight line.