JPH0793405B2 - Method for manufacturing spot-shaped partial clad material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a spot-shaped partial clad material by superposition pressure welding and rolling, and relates to a metal foil piece having a required size at a high precision pitch on a substrate material that is fed at a fixed size. By temporarily pressing the material, the rolling load is controlled so as to have a predetermined thickness when rolling, and by controlling the rolling load by detecting the position from the required point of the metal foil piece before and after rolling, The present invention relates to a manufacturing method for obtaining a spot-shaped partial clad material in which a metal foil piece is attached at a required position with high accuracy.

BACKGROUND ART In recent years, there has been a strong demand for miniaturization of devices using integrated circuits, and flat packages have come to be widely used.

The lead frame (3) as shown in FIG. 6 in which terminals are provided in the four circumferential directions for such a flat package has a metal (Al, Ag, Cu, etc.) having good bondability attached to a portion where wire bonding is performed. It is necessary to provide a part.

In order to previously provide such a metal-deposited portion, it has been conventionally performed by a. Vapor deposition method and b. Plating method after processing into a lead frame, but a method having higher mass productivity has been desired.

That is, a. The evaporation method not only requires expensive equipment,
Since it is necessary to mask the unnecessary portions to be deposited, the vapor deposition speed is slow and the productivity is low. In addition, b. The plating method has a metal that cannot be plated, and there is a limit to the thickness that can be plated efficiently.

Further, in order to preliminarily provide the metal-deposited portion, as shown in FIG. 5, the metal-deposited portion (2) is provided in a spot shape on the lead frame material (1) with high accuracy, and press-working or A method of forming by etching can be considered.

For example, striped Al or Ag on the lead frame strip
A technique has been proposed (Japanese Patent Publication No. 63-51798) for mechanically or chemically removing unnecessary portions so that a desired spot shape can be obtained after the foil is pressed and rolled. The yield was poor, the efficiency was poor, such as masking the required area for deposition to remove the unnecessary area, and it was difficult to provide spots with the required pitch and dimensions with high accuracy.

It is also possible to produce a spot-shaped partial clad material of a certain length by stacking a piece of metal foil of a certain size on a certain position of a certain length of the substrate material, and pressing and rolling it. It is impossible to cut back the metal foil to be adhered with high precision with a certain size and length in succession, align it with high precision, and provisionally fix it continuously at the required pitch. Industrial mass production of clad materials was considered impossible.

On the other hand, a lead frame in which an Al foil is fastened to the lead frame material by spot welding and then clad is proposed (Japanese Patent Laid-Open No. 60-227456). No specific manufacturing method has been proposed for aligning with precision and for temporary temporary fixing, which makes practical application difficult.

Furthermore, if the spot welding is only temporarily performed, the Al foil will be constrained at the welded portion and its rollability will be problematic, and there will be a problem that the required pitch and dimensional accuracy cannot be improved simply by pressure welding. It was

That is, conventionally, the metal foil clad by pressure contact rolling is a stripe clad, and the target of control is the plate thickness, plate width, and shape, but the pitch fluctuation that occurs in the pressure contact rolling of the metal foil in which the metal foils are superposed at a predetermined pitch. Is due to variations in rolling conditions, plate thickness and plate width.

In particular, the influence of plate thickness fluctuation is very large. For example, when the material plate thickness is 0.254 mm, the material pitch is 30 mm, and the finished plate thickness is 0.15 mm, the pitch changes by 400 μm or more just by changing the finished plate thickness by 0.001 mm. become.

Further, as described above, in order to process the spot-shaped partial clad material into a lead frame having a complicated pattern as shown in FIG. 6, a press working method can be considered. It is necessary to punch out the required pattern.

That is, press working is performed by using a dozen or more different molds having a length that can be opposed to a required number of metal foils, but when the substrate material length is the same as the mold, the pitch of the metal foils is to some extent. Pressing is possible even if there is an error.

However, if the spot-shaped partial clad material of the strip material is pressed several times in succession, even if there is a slight error in the pitch of the metal foil, if this is accumulated, the position of the metal foil will shift and the press Machining becomes impossible, and it is necessary to cut out the misaligned portion and perform new cueing again, resulting in a significant decrease in yield.

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a spot-shaped partial clad material having a highly accurate pitch and dimensions that can obtain a spot-shaped partial clad material of a strip material and continuously process this into a lead frame. For the purpose of, when the metal foil to be adhered is cut with high precision with a predetermined size and length, aligned with the lead frame material with high precision and temporarily temporarily fixed, then pressure-welded, rolled and clad. Another object of the present invention is to provide a manufacturing method capable of providing a spot-shaped partial clad material in which a metal foil is attached to a required position with high accuracy.

SUMMARY OF THE INVENTION The present invention is a method for producing a spot-shaped partial cladding material by pressure-rolling a material in which metal foil pieces having a required size are temporarily fixed on a substrate material at a predetermined pitch. From the dimensions and the dimensions of the metal foil pieces and the pitch between the metal foil pieces, the rolling load for obtaining the target pitch and the plate thickness is set, and pressure contact rolling is performed by a means for controlling the rolling load to the target, Furthermore, the position of the metal foil piece is measured on the delivery side of the rolling mill, and the rolling reduction during continuous rolling is performed according to the difference between the target position and the measured position of the required number of metal foil pieces from the preset origin on the substrate material. A method for manufacturing a spot-shaped partial clad material, characterized in that the force is corrected and controlled.

Further, according to the present invention, in the above structure, the position of the metal foil piece is measured on the delivery side of the rolling mill, and the set value of the target load is corrected and controlled by the position measurement value from the required origin of the metal foil piece before rolling. And a method for manufacturing a spot-like partial clad material.

To be more specific, the present invention is, for example, after the fixed-size feeding of the metal foil and the substrate material is continuously spot-welded at a required interval and temporarily fixed, then an unnecessary portion is removed by a rotary cutter, or,
At the same time as punching and cutting the metal foil fed at a fixed size with a punch, the punch is spot-welded as a current-carrying material on the substrate material that is fed at a fixed size and temporarily fixed, and a metal foil piece of the required size is temporarily fixed at a highly accurate pitch. After the material is obtained, the rolling load is controlled so as to have a predetermined thickness during the subsequent pressure welding and rolling, that is, the constant load control and the constant elongation control are cascade-controlled, and the required point of the rolled metal foil piece is adjusted. It is a manufacturing method for obtaining a spot-shaped partial clad material which can control the plate thickness with ultra-high accuracy by detecting the position and control to the target load, and which has high-accuracy pitch and dimensions.

Structure and effect of the invention Pitch variation of the metal foil piece in the pressure contact rolling of the substrate material, a.
Feedback due to fluctuations in board thickness, b. Fluctuation of roll gap eccentricity roll gap (plate thickness)
It is necessary to control the plate thickness with ultra-high accuracy by making full use of feedforward.

In the present invention, in the pressure contact rolling, the rate of change of the strip width can be considered to be much smaller than the rate of change of the sheet thickness, and the pitch can be controlled by controlling the rolling rate Re to be constant.

V = L ₀ h ₀ b = L ₁ h ₁ b L ₀ = L ₁ h ₁ / h ₀ = L ₁ / Re V; volume, h ₁ ; base metal plate thickness, h ₀ ; pressure plate thickness, b; plate Width, L ₁ ; Base material pitch, L ₀ ; Rolling pitch By the way, the rolling load P k _m ; deformation resistance, R: roll radius considering flatness, Q _P ; expressed as a rolling force function, which makes it possible to control the pitch by controlling the target rolling load, but the rolling force function Q _{Since P} changes depending on the friction conditions and the like, it is necessary to correct this.

Therefore, in the present invention, a position measuring device for the metal foil is provided on the delivery side of the rolling mill, and in accordance with the difference between the target position and the measured position of the metal foil piece from the required origin, the rolling force function Q _P during continuous rolling is included. By controlling feedback of rolling load to the comprehensive correction, it became possible to control the plate thickness with ultra-high accuracy and realize the target position control of the metal foil.

Furthermore, when setting the target rolling load, a position measuring device for the metal foil piece is provided on the inlet side of the rolling mill, the difference between the target position and the measured position of the metal foil piece before rolling is measured, and the measured value is feedforward. However, the plate thickness control can be performed with higher accuracy and speed by always or appropriately correcting the target load setting value.

According to the present invention, it is possible to reduce disturbances such as a. Periodic fluctuations caused by eccentricity of rolling rolls, b. Gentle fluctuations caused by the influence of the amount of oil film, etc., which occur in pressure contact rolling of substrate materials in which metal foils are superposed at a predetermined pitch. Therefore, it is possible to provide a material that enables ultra-high-precision pitch control and is excellent in mass productivity when forming a lead frame by pressing or etching.

In the present invention, the substrate material serving as the clad base material, any known material such as 42Ni-Fe system used as a lead frame material can be applied, and the metal foil pressed in a spot shape is Ag, Ag-Cu, or the like. Known brazing materials such as Ag brazing material, Al, Cu and the like can be used.

Disclosure of the Invention Based on the Drawings FIG. 1 is a schematic explanatory view of a rolling mill showing a pressure contact rolling method according to the present invention.

2A, 2B and 2C are explanatory views showing the pitch measuring device.

FIGS. 3a, 3b, 3c, 3d and 3f are schematic explanatory views showing the manufacturing process of the rolled material, and FIGS. 3c and 3e are schematic explanatory views of the welding device and the cutting machine viewed from the line direction.

4A to 4E are schematic explanatory views of an embodiment of a constant size feeding and welding apparatus showing a manufacturing process of a rolled material, and FIG. 4A is an explanatory view seen from the line direction.

This invention, in the pressure contact rolling of the substrate material in which the metal foil is superposed at a predetermined position, that is, a predetermined pitch, from the dimensions and the pitch of the substrate material and the metal foil piece, or further, each metal from the required origin before rolling. From the position of the foil piece, set the target absolute position from the required origin after rolling and the target rolling load to obtain the plate thickness, and hold the rolling load at the target, or press-contact rolling by means of controlling to a required value. ,further,
It is characterized in that a pitch measuring device for a piece of metal foil is provided on the delivery side of the rolling mill, and means for correcting and controlling the rolling force during continuous rolling is used according to the difference between the pitch measurement value and the target pitch.

However, the target pitch cannot be controlled with high accuracy unless the metal foil is superposed on the base material of the rolled material with high accuracy. Therefore, first, a method for obtaining the material will be described.

Configuration 1 As shown in FIG. 3, the metal foil (11) guide mechanism feeds the substrate material (10) to a predetermined position on the substrate material (10), and the series spot welding device (13) at which the electrode can be opened and closed at the position is used for the substrate material (10 ) And metal foil (11) are sent. At this time, it is necessary to allow for the predetermined feed amount in consideration of the amount of deformation by press rolling and finish rolling (see FIG. A).

When the electrode (14) is lifted and the welding current-carrying material (15) presses the metal foil (11) onto the substrate material (10), the electrode (14) is pressurized and energized to weld the metal foil ( (See Figures b and c).

At this time, it is desirable to weld the molten metal so that the size of the molten metal does not appear on the surface of the metal foil.
It is good to arrange more than one point in the width direction.

In particular, as shown in FIG. 3c, it is preferable to weld two points on both ends of the metal foil piece (11) in the width direction of the substrate material (10), and only the tip side that is caught in the roll at the time of rolling in the subsequent process. By temporarily fixing and making the rear end side free, pressure welding and rolling property are improved.

A metal foil (11) fixed to a portion of the substrate material (10) located at an integral multiple of a predetermined pitch from the above welding device is cut into a predetermined length by a circular cutter (16) arranged at a predetermined interval, and the metal foil (11) is cut. ) Is shaped (see figures d and e).

At this time, it is necessary to allow for the amount of deformation of the predetermined length by pressure contact rolling and finish rolling.

After cutting, by removing the non-welded portion, it is possible to obtain a metal foil piece (12) having a predetermined size that is temporarily fixed by spot welding and has a good shape.

For example, after performing the above steps, a cycle of simultaneously performing the steps is repeated to obtain a substrate material (10) in which metal foil pieces (12) are continuously temporarily fixed at a required pitch. The substrate material (10) obtained by temporarily fixing the metal foil piece (12) thus obtained is once wound around a coil, or
After the above process is completed, it is possible to directly shift to the pressure contact rolling process.

However, whichever method is adopted, pressure contact and reduction of rolling property (damage to the metal foil piece (12), position of the metal foil piece (12) due to restraint by temporarily fixing the metal foil piece (12) as described above are caused. Considering that a highly accurate shape cannot be obtained due to misalignment, wrinkles, etc.), it is desirable that only the front end side that bites into the roll during rolling is temporarily fixed and the rear end side is free.

Structure 2 As shown in FIG. A metal foil (11) having a predetermined width is fed into the cutting device by a predetermined amount by a constant-size feeding device having an attaching / detaching mechanism by a suction machine (21).
(See Figure c) When the metal foil (11) of a predetermined length overhangs from the end face of the guide (20), the punch (22) is lowered and the metal foil (1
Cut 1) into metal foil pieces (12). (See Figure d) When the metal foil piece (12) cut by the punch (22) is pressed against the substrate material (10), pressure is applied to the roller electrode (23) to weld the metal foil piece (12) (e). See figure). The welding conditions at this time are preferably the same as those described above.

After the spot welding is completed, the substrate material (10) is fed by the constant-size feeding device in a predetermined amount, that is, an amount in which the deformation amount due to the pressure contact rolling and the finish rolling is expected.

For example, After performing the process at the same time, By repeating the process cycle, the metal foil strip (1
A substrate material (10) in which 2) is temporarily temporarily fixed at a required pitch is obtained. The substrate material (10) obtained by temporarily fixing the metal foil pieces (12) thus obtained is wound around a coil once or It is possible to directly shift to the pressure contact rolling step after the step of (3) is finished, and it is also the same as that described above in consideration of the temporary fixing point in order to improve the pressure contact and the rolling property.

Next, a method for press-rolling the obtained substrate material (10) and metal foil piece (12) will be described. In the following method, the substrate material (10) formed by temporarily fixing the metal foil piece (12) described above.
Uses a coil once wound up.

As shown in FIG. 1, the rolling mill (30) has a structure in which a backup roll (32) is brought into contact with a pair of work rolls (31) to pressurize the rewound substrate material (10). Equipped with a device and a plate thickness gauge, the rolling load control device performs constant load control.

Furthermore, a position measuring device for the metal foil piece on the exit side of the rolling mill (30), here, an optical sensor (38), a high precision encoder (34)
Is provided.

The control method consists of the following procedures.

I Based on the measurement value of rolling load and the absolute position measurement value of the metal foil piece from the required origin at that time, the quantitative relationship between the variation of rolling load and the variation of pitch and absolute position, and the control model were obtained. The target rolling load for obtaining accuracy is calculated, and III constant rolling control is performed by outputting the rolling load as a control reference.

IV In addition, the position measurement result of the metal foil piece is fed back to the rolling load control device to correct the control model appropriately for the control error and comprehensively correct it.

With such control, it is possible to control the plate thickness with extremely high accuracy during rolling, and it is possible to realize the target high-accuracy pitch control.

Further, in II, it is possible to feed-forward the absolute position measurement value of the metal foil piece before rolling from the required origin, and constantly or appropriately correct the target setting value of the rolling load.

As shown in FIG. 2, a known sensor such as an optical sensor (33) is used as a position measuring device for the metal foil piece, and a substrate material (10) is used.
Detects a metal foil piece (12) in the width direction (Fig. A), substrate material (10)
In addition to detecting the metal foil strip (12) in the longitudinal direction (Fig. C), the optical sensor (33) and high-precision encoder (34) are used (Fig. B) to detect the metal foil strip (12) from the required point. The position can be measured.

Practical example 10mm with the sandwich cutting and spot welding method shown in Fig. 4.
42mm width, 0.25mm thickness 42Ni-Fe material that temporarily and temporarily fixed Al foil pieces of width, 10μm thickness, 6.4mm length at 36.0mm pitch was used, and the target substrate thickness after rolling was 0.15mm, Al foil. The target pitch of one piece was set to 60.0 mm.

For example, in the rolling mill shown in FIG. 1, the backup roll is periodically eccentric, and the rolling force fluctuates due to other rolling conditions. Due to such fluctuation, the pitch fluctuation width of the metal foil piece is about It becomes ± 800 μm.

To keep the target pitch accuracy within ± 300 μm to ± 100 μm, the tacking accuracy is ± 30 μm at 0.25t and ± 50 at 0.15t.
If the pitch accuracy is ± 300 μm, it is necessary to control the rolling thickness control accuracy width in the submicron order. Therefore, it is considered difficult to simply control the rolling thickness as the pitch control.

The effect of roll eccentricity on the plate thickness is that if the load variation on the kiss roll fluctuates by ± 0.5 ton, the gap variation is ± 2 μm at a mill constant of 74 ton / mm, and the plate thickness is about 1/2 of that. 1
Equivalent to μm, if the plate thickness fluctuates ± 1 μm, the elongation is ± 60
It varies by 0 μm.

Therefore, by using the rolling mill shown in FIG. 1, the cascade control system of constant load control and constant elongation control and the measurement result of the metal foil piece position measuring device are fed back to the rolling load control device for correction. When rolled by the control method of 10mm width, 10.7mm on the substrate material of 42mm width, 0.15mm thickness
The length of the Al foil piece can be clad, and the absolute position accuracy of the metal foil piece is improved more than 10 times compared to the method that does not control the rolling load. It was possible to obtain a material in which the pieces were partially clad in a spot shape.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a rolling mill showing a pressure contact rolling method according to the present invention. 2A, 2B and 2C are explanatory views showing the pitch measuring device. FIGS. 3a, 3b, 3c, 3d and 3f are schematic explanatory views showing the manufacturing process of the rolled material, and FIGS. 3c and 3e are schematic explanatory views of the welding device and the cutting machine viewed from the line direction. 4A to 4E are schematic explanatory views of an embodiment of a constant size feeding and welding apparatus showing a manufacturing process of a rolled material, and FIG. 4A is an explanatory view seen from the line direction. FIG. 5 is a perspective explanatory view of the spot-shaped partial clad material. FIG. 6 is an explanatory diagram showing an example of a lead frame. 10 …… Substrate material, 11 …… Metal foil, 12 …… Metal foil piece, 13 …… Welding device, 14 …… Electrode, 15 …… Electrical material, 16 …… Circular cutter, 20 …… Material guide, 21… … Suction machine, 22 …… Punch, 23 …… Roller electrode, 30 …… Rolling machine, 31 …… Work roll, 32 …… Backup roll, 33 …… Optical sensor, 34 …… High-precision rotary encoder.

Claims (2)

[Claims] 1. A manufacturing method for obtaining a spot-shaped partial cladding material by pressure-rolling a material in which metal foil pieces of a required size are temporarily fixed on a substrate material at a predetermined pitch between adjacent substrates. From the size of the plate material and the size of the metal foil pieces and the pitch between the metal foil pieces, a rolling load for obtaining the target pitch and the plate thickness is set, and pressure rolling is performed by means of controlling the load with the rolling load as a target. Further, the position of the metal foil piece is measured on the delivery side of the rolling mill, and the metal foil piece is measured according to the difference between the target position and the actually measured position of the required number of metal foil pieces from the preset origin on the substrate material. A method for producing a spot-like partially clad material, characterized in that the rolling force during continuous rolling is corrected and controlled to control the pitch of the strip. 2. A device for measuring the position of a metal foil piece is provided on the entrance side of the rolling mill, and means for correcting and controlling the set value of the target load is used by measuring the position of the metal foil piece before rolling from the required origin. The method for producing a spot-like partially clad material according to claim 1, which is characterized in that.