JPH04728A - Method and device for application of fixing agent for semiconductor chip - Google Patents

Abstract

PURPOSE:To enable application of adhesive fixing agent in a uniform thickness to a desired application shape by pressing a pressing body having a recessed part corresponding to an application shape and an application thickness to supplied fixing agent, by separating it after formation and by mounting a semiconductor chip on the formed fixing agent thereon. CONSTITUTION:A rod-shaped pressing body 18 is arranged on a pressing stage which is spaced (n) times a forward feed pitch P away from a dispensor 17. A recessed part 18b is formed on a pressing surface 18a of an edge face of the pressing body 18. The recessed part 18b is shaped to almost coincide with an application shape whereto fixing agent 14a is applied, and a thickness of the recessed part 18b is made to correspond to a scheduled application thickness. When the recessed part 18b is formed of a material of good release characteristics such as fluorocarbon resin and polyethylene, a depth thereof is made coincide with a thickness thereof. If it is formed of such materials as to make fixing agent remain in the recessed part 18b when the pressing body is separated, the depth is made larger than the thickness corresponding to a remaining amount. Accordingly, the fixing agent 14a, which is heaped up on the pressing stage before pressed, is applied as fixing agent 14b of desired shape and thickness by pressing.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method for fixing semiconductor chips obtained through a semiconductor wafer process to a substrate such as a metal lead frame by reducing the viscosity of solder paste, adhesive, etc. The present invention relates to a method and apparatus for applying a bonding agent to a semiconductor chip that satisfactorily applies a certain bonding agent to a substrate.

[Conventional technology]

FIG. 4 is a sectional view of a general semiconductor device common to the conventional technology and the technology of the present invention.

In the figure, a semiconductor chip 3 obtained through a wafer process is fixed onto a metal substrate 2 integrally provided with leads 1 using solder 4, and the electrodes of the semiconductor chip 3 and the leads 1 are connected using thin metal wires 5. The main parts including the semiconductor chip 3 are molded with a synthetic resin 6 to obtain a semiconductor device 7. The semiconductor chip 3 is fixed with the solder 4 by applying a solder paste made of a powdered solder alloy and Franks to the substrate 2, placing the semiconductor chip 3 thereon, and heating it. This is the technology of

There are two conventional techniques for applying solder paste to a board:

(1) A method of supplying a desired amount of solder paste by dropping it onto the board from a thin tube at the tip of a tubular dispenser.

(2) Place a screen mask made of a thin plate on the board,
A method of rubbing solder paste over the solder paste with a plate-shaped spatula.

In addition to the above-mentioned solder paste, adhesives for fixing semiconductor chips to substrates include brazing adhesives and organic adhesives.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, in method (1), the dripping supply method using a dispenser, the solder paste rises up in a mountain shape, and when a semiconductor chip is placed on top of it, the solder paste evenly spreads to the bottom surface of the semiconductor device knob. Good coating cannot be achieved because the coating does not spread and protrudes to one side, or is insufficient to the other, and as a result, poor adhesion tends to occur. Moreover, if too much solder is used, the solder may protrude and cause a short circuit, and thick solder may increase thermal resistance.

In method (2), the screen mask method, the edge of the window of the shape to be coated needs to have sufficient margin for the movement of the spatula, and the screen mask is considerably larger than the window, making it difficult to use the semiconductor device described above. It is difficult to use devices where the height of the board and the leads are different.

An object of the present invention is to develop a semiconductor chip that can apply viscous adhesives such as solder paste, brazing agent, adhesive, etc. to a desired coating shape and to different thicknesses even when the substrate and lead heights are different. An object of the present invention is to provide a method and apparatus for applying a fixing agent.

[Means to solve the problem]

The method for applying a bonding agent for a semiconductor chip according to the first aspect of the invention includes supplying a desired amount of a viscous bonding agent onto a substrate to which a semiconductor chip is to be bonded, and then determining the shape of the coating and applying the bonding agent. A pressing body having a concave portion corresponding to the thickness is pressed against the supplied adhesive to form the adhesive, and then separated, and then a semiconductor chip is placed on the molded adhesive.

Invention 20 A device for applying a adhesive for semiconductor chips includes a transport rail on which a plurality of substrates are placed and sequentially conveyed at a predetermined pitch, and a dispenser disposed on a supply stage of the transport rail to supply a desired amount of a viscous adhesive. , a pressing body disposed on the pressing stage of the conveyance rail and having a pressing surface consisting of a concave portion corresponding to the coating shape and coating thickness to which the adhesive is to be applied, and driving the pressing surface of the pressing body up and down. The predetermined pitch is one integer of the distance between the supply stage and the push stage.

In addition, the pressing body of Invention 1 or 2 is a bar-shaped pressing body with a pressing surface consisting of a concave portion on the end face, or a thin cylindrical pressing body with a pressing surface consisting of a concave portion on the cylindrical surface. can. In the latter case, when the pressing body is rotated, the pressing surface moves up and down.

[Effect]

In invention 1, the viscous adhesive supplied in a desired amount onto the substrate is usually in a heaped shape, and at least the outer edge of the heaped adhesive is within the range of the recess of the pressing body. If so, the fixing agent will spread into the recess by pressing with the pressing body after being supplied and will be applied to a thickness corresponding to the depth of the recess, and the application shape and application thickness can be controlled. The recesses should be made of a material that has good release properties against the adhesive, such as fluororesin or polyethylene, but if the adhesive remains in the recesses, the volume of the recesses should be covered by that amount. The desired coating volume should be larger than the area of the coating shape multiplied by the coating thickness. Even in this case, since the amount remaining in the recess is approximately constant each time, the amount supplied onto the substrate is made equal to the desired coating volume.

In invention 2, the substrate to which a desired amount of adhesive is supplied by the dispenser on the supply stage of the transport rail is transported directly below the pressing body on the pressing stage as the transport rail sequentially moves. The pitch of forward feeding is an integer n/1 of the interval between both stages.
At this time, the substrate reaches the pressing stage from the supply stage after being sequentially fed n times. The effect of applying the fixing agent onto the substrate in a desired shape and thickness by such supply and pressing is the same as that of the first invention.

〔Example〕

FIG. 1 is a vertical cross-sectional view of the coating device of Example 1 in the forward feeding direction, showing the II section in FIG. 2, and FIG.
3 is a sectional view of the driving device portion of the second embodiment. Components given the same reference numerals as in FIG. 4 and each figure have roughly the same functions, and their explanations may be omitted below.

In FIGS. 1 and 2, a substrate 2 integrally provided with leads 1 has an edge 1a on the opposite side of the leads 1 as shown in FIG. 2 for convenient transportation during the manufacturing process. The edge portion 1a is cut off when the semiconductor element 7 is a completed product.

Now, the board 2 with the leads 1 and the edge 1a is connected to the transport rail 1.
5 and is conveyed sequentially at a predetermined pitch P. At the supply stage of the conveyor rail 15, a desired amount of a fixing agent 14 such as a paste is dispensed by a known quantitative supply controller 16.
A dispenser 17 is arranged to supply a.

Then, from this dispenser 17, sequentially feed the n of P.
A rod-shaped pressing body 18 is arranged on a pressing stage that is twice as far away. A recess 18 is formed on the pressing surface 18a of the end surface of the pressing body 18.
b is formed, the shape of the recess 18b is made to approximately match the shape of the adhesive 14a to be applied, and the depth of the recess 18b is made to correspond to the thickness to be applied. When the recess 18b is made of a material with good mold releasability such as fluororesin or polyethylene, the depth is made to match the thickness, and when the recess 18b is made of another material and the adhesive remains in the recess 18b when the pressing body is separated,
The depth is made larger than the thickness by an amount commensurate with the remaining amount.

The pressing body 18 is guided by a cylindrical guide 20 via a spring 19, and is driven up and down by a drive device 21 such as a cylinder. The drive device may be a cam 23 driven by a motor 22 as shown in FIG. 3 showing the second embodiment, or other known devices such as a link device may be used. In this case, if the drive device is used to properly move the pressing body up and down, the spring 19 is not essential, and a slight dimensional difference can be absorbed by the vertical elasticity of the conveyance rail.

Before pressing at the pressing stage, a heaping amount of the adhesive 14a is applied as a adhesive 14b having a desired shape and thickness by pressing.

Furthermore, if m dispensers 17 and pressing bodies 18 are arranged consecutively at the same intervals, and the first dispenser 17 and the first pressing body 18 are placed apart from each other by a distance that is an integral multiple of P, the processing speed will be multiplied by m. .

Although not shown, a thin cylindrical pressing body may be used instead of the rod-shaped pressing body 18. The outer peripheral surface of this pressing body is a pressing surface having one or more recesses, and the length in the circumferential direction between the recesses is synchronized with the progressive pitch P of the substrate. The drive device may be a known motor with a step motion or a so-called active drive with friction or without slippage, such as by means of the edge 1a.

〔Effect of the invention〕

The method for applying a bonding agent for a semiconductor chip according to the first aspect of the invention includes supplying a desired amount of a viscous bonding agent onto a substrate to which a semiconductor chip is to be bonded, and then determining the shape of the coating and applying the bonding agent. A pressing body having a concave portion corresponding to the thickness is pressed against the supplied adhesive to form the adhesive, and then separated, and then the semiconductor chip is placed on the molded adhesive. In cases where a screen mask cannot be used and a dispenser is used in cases where the lead height is different, the application shape and the uniform application thickness correspond to the shape and depth of the concave part of the pressing body. This has the effect that the adhesive is applied, the semiconductor chip and the substrate are bonded well, and a minimum bonded layer with low thermal resistance, ie, good cooling, can be obtained.

In addition, the semiconductor chip adhesive application device according to the second aspect of the invention includes a transport rail on which a plurality of substrates are placed and sequentially conveyed at a predetermined pitch, and a supply stage of the transport rail that is arranged to supply a desired amount of viscous adhesive. a dispenser, a pressing body disposed on the pressing stage of the conveyance rail and having a pressing surface consisting of a concave portion corresponding to the application shape and coating thickness to which the adhesive is to be applied; The predetermined pitch is set to be an integral fraction of the interval between the supply stage and the pushing stage, so that the substrate is sequentially fed at a pitch P, and is fixed from the dispenser after an integer n number of sequential feeds. The substrate that has been supplied with the agent is transported directly below the pressing body, and by the action of Invention 1, a coating layer with the desired coating shape and coating thickness is formed, realizing a coating device that can be mass-produced. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view in the forward feeding direction of the coating device of Example 1, showing the 1-1 cross section in FIG.
-n sectional view, FIG. 3 is a sectional view of the driving device portion of the second embodiment, and FIG. 4 is a sectional view of a general semiconductor device common to the conventional technology and the technology of the present invention. DESCRIPTION OF SYMBOLS 1... Lead, 2... Substrate, 3... Semiconductor chip, 4... Solder, 7... Semiconductor device, 14a, 14
b... Adhesive agent, 15... Conveyance rail, 17... Dispenser, 18... Pressing body, 18a... Pressing surface,
18b... recess.

Claims (1)

[Scope of Claims] 1) After supplying a desired amount of a viscous adhesive onto a substrate to which a semiconductor chip is to be adhered, a recess corresponding to the coating shape and coating thickness to which the adhesive is to be applied is provided. Application of a fixing agent for a semiconductor chip, characterized in that a pressing body equipped with the above is pressed against the supplied fixing agent to form it, and then separated, and then a semiconductor chip is placed on the molded fixing agent. Method. 2) A transport rail on which a plurality of substrates are placed and sequentially fed at a predetermined pitch, a dispenser arranged on a supply stage of this transport rail to supply a desired amount of viscous adhesive, and a dispenser arranged on a pressing stage of the transport rail. It consists of a pressing body having a pressing surface consisting of a concave portion corresponding to the coating shape and coating thickness to which the fixing agent is to be applied, and a drive device that drives the pressing surface of this pressing body up and down, An apparatus for applying a bonding agent for a semiconductor chip, wherein is set to an integral fraction of the distance between the supply stage and the push stage.