JPS62296978A - Manufacture of clad material - Google Patents

Abstract

PURPOSE:To remove the foreign matters of the metal powder, etc. adhered to a work roll and stabilize the cladding effect by passing the resin tape in the specific thickness with its rolling at the junction point of a work roll and backup roll. CONSTITUTION:The foreign matter adhered to a work roll 6 is removed by delivering from a supply reel 15 the synthetic resin tape 16 of a polyester, polychloride vinyl, polyethylene, 'TEFLON(R)' etc. in 0.005-0.10mm thickness to the position where the upper and lower work roll 6 and backup roll 7 are adjoining. In this way, the quality improvement of the product surface is realized and the cladding effect can be stabilized as well.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of manufacturing a strip-shaped material used for lead frames of semiconductor devices and semiconductor integrated circuits, and more specifically, , relates to a method of cold-welding a strip of a good conductive material made of a different material from the base material to the surface of a strip-shaped base material using a pressure welding roll.

[Conventional technology]

The materials used for lead frames of semiconductors or semiconductor circuits are usually composite materials made by combining two or more metals, one for mechanical strength and the other for conductivity, and clad with a strip-shaped thin plate.

To give an example, as shown in Figure 1, high-strength and corrosion-resistant alloys such as Pe-Ni alloys and Fe-Ni-Co alloys with thermal expansion coefficients closer to those of glass are used. ?
A plate width band 2 of a conductive material of a different grade from these is cold-welded to the surface of a band-shaped base material 1 made of e-alloy or Cu alloy.

Conventionally, as shown in Fig. 3, a method for manufacturing such a rad material is to unwind a strip-shaped base material 1 from a bobbin in which it has been wound, and similarly to unwind a strip 2 having a width of a good conductive material from the bobbin. At the same time, they are stacked on top of each other and passed through pressure welding rolls such as four-tiered rolls, and are then cold welded together.
Alternatively, there is a method of successively cold rolling the material to a predetermined thickness, obtaining a cladding material, and winding it.

Generally, the surface of the metal strip fed out from the bobbin is cleaned by polishing it with a wire brush 5 or the like, and the roll pressure welding machine uses a backup roll 7 to apply pressure to the work roll 6. Typically, a supporting multi-high rolling mill is used. When performing pressure welding using this rolling mill, it is necessary to supply liquid lubricant to the rolls for lubrication and cooling, so the lubricant spout 8 is placed close to the circumference of the work roll or backup roll. Things are being set up.

Normally, in this type of composite material, the strip of good conductive material plate width that is pressure-welded is extremely thin, with a thickness of 0.005 to 0.1 a1m, and the base material is thick and highly rigid. , It is technically quite difficult to join these two dissimilar metal strips and finish them to the specified dimensions.

[Problem that the invention seeks to solve]

When a cladding material is manufactured by the method using the above-mentioned pressure roll, foreign matter of various sizes may sometimes adhere to the cladding material, and partial peeling or flaws may occur on the cladding material.

The main causes of these foreign matter adhesion, peeling and scratches are
In the process of press-welding materials, metal powder may be mixed into the lubricant supplied to improve the lubrication between the work roll and the material, and these foreign substances may be directly press-fitted onto the surface of the clad material, or the work roll may be It is strongly baked into the surface and becomes convex, causing scratches on the surface of metal materials that are good electrical conductors. The cladding material used for lead frames of semiconductor devices and semiconductor integrated circuits is punched into the shape of the lead frame as shown in Fig. 2(a), and then the lead frame is stamped as shown in Fig. 2(b). An aluminum wire or gold wire (bonding wire 14) for electrically connecting the IC chip and the IC chip is bonded to the good conductor portion 3 at the tip of the lead pin 4.

In this bonding process, the foreign matter adheres to the cladding material,
Partial peeling or flaws will result in poor bonding and impede the functionality of the IC. In order to ensure high reliability of ICs, it is strongly required to provide materials free of these defects.

In order to prevent the foreign matter from adhering to the work roll, it is possible to install a jig for removing and cleaning the foreign matter near the surface of the work roll, but this can be seen in the example of the four-tier roll shown in Fig. 3. The space near the surface of the work roll is extremely narrow, making it difficult to place jigs effectively.
Not practical.

[Printing of invention]

The present inventors made various improvements to the conventional pressure welding device using four-tiered rolls, tried Th11 method of improving the method to prevent adhesion of foreign matter, and tested the reproducibility of the effect. It is of course important to eliminate foreign substances in the lubricant, but even if the lubricant filtration device is made larger and more precise, it will not be perfect, and it will not be effective despite the high cost of installing it. There wasn't. On the other hand, as a method for mechanically sweeping the surface of the work roll to remove foreign matter, since there is no space to install a cleaning jig such as a brush near the surface of the work roll, a consumable wiper tape is used instead of the jig. When we devised and tested a method of continuously supplying foreign matter, thereby adsorbing and enclosing foreign matter and removing it from the roll surface, we found that it was more effective than expected.ff SR.

The present invention will be specifically explained below using Examples.

As shown in FIG. 3, the thickness is 0.2 to 1. A Pe-Ni-Co alloy tape base material 1 with a width of 0mm and a width of ZOmm-60mm is fed out from a reel hung on a supply stand, the surface to be cladded is polished and cleaned with a wire brush 5, and then placed near the entrance of the work roll (6). , thickness 0.005-0.10m, also derived from the supply reel.
Aluminum foils 2 with a width of LI-myn ~/5' inch were stacked and pressed together using a four-roll pressure welding machine consisting of a work roll 6 and a backup roll 7.

=:, f In the case of uninvention, a synthetic resin such as polyester, polyvinyl chloride, polyethylene, Teflon, etc. with a thickness of 0.005 to 0.10 mm is placed at the position where the upper and lower work rolls and their backup rolls come into contact during this pressure welding. tape 1
6 from the supply reel 15, and while the pressure welding work continues, the resin tape is constantly supplied and passed through the joint between the work roll and the backup roll (in other words, the resin tape is rolled as if it were being rolled between the work roll and the backup roll). The foreign objects and metal powder adhering to the workloaf were scraped off or contained with tape and carried away. This resin tape passes through a roll pressure welding machine in a direction opposite to the direction in which the base material and the like pass, and after fulfilling its role, is wound up on a take-up reel 17 and discarded.

If the thickness of the resin tape was less than 0.005 mm, accidents such as breakage due to foreign metal powder or the like would occur frequently, and the inclusion and removal of foreign matter could not be carried out effectively. Further, when the thickness exceeds 0.10 mm, the pressing force applied by the backup roll to roll down the work roll becomes unbalanced in the longitudinal direction of the roll, making it difficult to maintain the shape of the cladding material normally.

It is recognized that the optimal value of the thickness of this resin tape varies slightly depending on the metal material and hardness of the base material to be clad, the cladding ratio, processing rate, etc., and the resin material also generally depends on the pressure required for rolling. The harder the resin, the better the results.

〔Effect of the invention〕

As explained in detail above, according to the method of the present invention, defects such as adhesion of foreign matter, embedding, peeling, scratches, and dents on the surface of the produced cladding material occur in the process of pressing the cladding material using a multi-stage pressure welding roll. Additionally, by adopting this method, the lubricant supplied to the work rolls is extremely thin and uniformly applied to the entire surface, making the pressure welding process itself extremely difficult. This also produces the effect of stabilizing the

As described above, the present invention provides a method for producing cladding materials of good quality at low cost and with high reliability by applying IWt using a relatively simple device, and is extremely useful industrially.

[Brief explanation of the drawings] , ¥J1 figure is a perspective view of the cladding material, figure 2 (a), (
b) is a perspective view and a sectional view showing a state in which the clad material is used as a lead frame of an IC, FIG. 3 is a schematic diagram of an apparatus showing a conventional method, and FIG. 4 is a schematic diagram of an apparatus implementing the present invention. 1: Band-shaped base material 2: Good conductive material plate width band 3: Good conductive material plate width portion at the tip of the lead bin 4: Lead bin 5:
Wire brush 6: Work roll 7 Backup roll 8: Lubricating oil spout 9: Clad material 10: Ceramic base 11: Ceramic cap 12: Low melting point glass 13: IC chip 14: Bonding wire 15: Resin tape supply reel 16: Resin tape 17: Resin tape winding reel,
,,,+11 Agent Patent Attorney Tetsuji Uedai ;,

Claims (3)

[Claims] (1) In a method for producing cladding material in which a strip of good conductive metal having a width smaller than that of the strip base material is vertically pressure-bonded to one or both sides of a strip base material of an alloy material, the pressure roll is a work roll and a backup roll. This is a multi-stage rolling mill with four or more stages consisting of a work roll and a backup roll, and a resin tape with a thickness of 5 to 100 μm is rolled through the joint point of the work roll and backup roll to remove metal powder etc. attached to the work roll. A method for producing a cladding material, characterized by adsorbing, enclosing, and removing foreign matter during pressure welding. (2) The alloy material as the strip base material is Fe-Ni alloy, F
The method for manufacturing a cladding material according to claim (1), characterized in that an Fe-based alloy such as an e-Ni-Co alloy or a Cu alloy is used. (3) The cladding ratio (ratio of the width of the conductive material to the width of the base material band) when press-welding the strip-shaped good conductive material to the strip-shaped base material is 0.
．． Claims (1) and (2), characterized in that the processing rate of press welding and cold rolling performed subsequent to press welding is 5 to 70%. A method of manufacturing the described cladding material.