JPH022546Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a dispenser type conductive paste supply device using a syringe.

Conventional technology Solder is generally used to fix semiconductor pellets onto hybrid IC boards and lead frames, but conductive paste has recently been used particularly for mounting low-power semiconductor pellets such as MOS and IC. . This conductive paste is made into a paste by kneading metal powder such as gold or silver with a solvent such as epoxy resin, and the stamping method is the method for quantitatively supplying it onto the pellet mount part of a hybrid IC board, etc. It is broadly divided into dispenser methods.

In the stamping method, a part of the conductive paste is spread to an equal thickness on a flat table and transferred to the stamp by contact with a stamp of a constant area, and then a constant amount of the conductive paste transferred to the stamp is transferred onto the pellet mount part. This is a method in which the image is transferred again and supplied.

The dispenser method uses a syringe filled with a large amount of conductive paste, and is introduced as a prior art in, for example, Japanese Patent Application Laid-Open No. 57-192036. This method's conductive paste supply device is shown in Figure 9. This will be explained below with reference to . In FIG. 9, 1 is a syringe, 2 is a conductive paste filled in the syringe 1, and 3 is a conductive paste 2 by applying an appropriate predetermined pressure to the conductive paste 2 in the syringe 1, and discharging the conductive paste 2 from the lower end of the nozzle 1'. This is a paste discharge amount control unit that discharges a fixed amount from the outlet 4. Reference numeral 5 denotes a pellet mount portion such as a conductive pattern or a lead frame of a hybrid IC board, onto which a fixed amount of conductive paste 2' is pressed by the paste discharge amount control unit 3 and is discharged from the paste discharge port 4 of the nozzle 1'. supplied.

Incidentally, after a certain amount of the conductive paste 2' is supplied onto the pellet mount part 5 in this way, for example, the first
As shown in FIG. 0, the semiconductor pellet 7 adsorbed by the vacuum adsorption collet 6 is supplied onto the conductive paste 2' to perform pellet mounting.

Problems to be solved by the invention By the way, the above-mentioned stamping type conductive paste supply device can supply a constant amount of conductive paste of equal thickness onto the pellet mount portion, and pellet mounting can be performed satisfactorily using conductive paste of equal thickness. However, it requires a device to spread the conductive paste to an equal thickness on a flat table, making the whole structure mechanically large, and if the size of the semiconductor pellet to be mounted changes, the stamp size must be adjusted to match this change. I had a problem where I needed to switch between the two. This problem is particularly severe in hybrid ICs in which multiple semiconductor pellets of different sizes and other electronic components are mounted on a single substrate, and has been an obstacle to reducing the number of steps required for pellet mounting.

In addition, the dispenser-type conductive paste supply device described above is mechanically simple and can adequately accommodate changes in pellet size by controlling the amount of paste discharged from the nozzle, but the shape of the conductive paste supplied onto the pellet mount is The following problem arose because the shape tends to be approximately hemispherical.

That is, as shown in FIG.
When mounting by pressing the conductive paste 2' on the pellet mount part 5, the conductive paste 2'
If the conductive paste 2' is approximately hemispherical, the conductive paste 2' spreads radially from the center of the back surface of the semiconductor pellet 7 to the periphery as shown by the arrow in FIG. The conductive paste 2' may not spread sufficiently to the back surface of the semiconductor pellet 7, which may weaken the mounting strength of the semiconductor pellet 7 after mounting and cause it to peel off later.
The heat dissipation properties of the semiconductor pellets 7 sometimes deteriorated. This problem of insufficient conductive paste under the semiconductor pellet can be solved by increasing the amount of conductive paste supplied, but in this case, the amount of conductive paste 2' that protrudes from the semiconductor pellet 7 increases. This is undesirable because it leads to shot defects and wasted material due to the conductive paste riding on the pellet, and the thickness of the conductive paste under the semiconductor pellet varies widely.

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems with the dispenser type conductive paste supply device. A cylindrical body is attached to the lower end of the syringe, the cylindrical body having a lower end surface centered on the paste discharge port at the lower end of the syringe, and a paste guide groove extending in a star shape with an inclined bottom centered on the paste discharge port on the lower end surface. That's what happened.

Effect According to this technical means, when the cylindrical body at the lower end of the syringe is brought into contact with or close to the pellet mount part and conductive paste is discharged from the paste discharge nozzle at the lower end of the syringe, the discharged conductive paste becomes pellets. The paste enters the paste guide groove of the cylindrical body on the mount part and spreads toward the tip of the paste guide groove. The amount of spread of this conductive paste is determined by the amount discharged at one time, so it can be adapted to changes in pellet size, and the thickness of the spread conductive paste is determined by the paste guide grooves being formed at a constant angle of inclination. The conductive paste becomes larger at the periphery where it spreads, and when the pellet is mounted, the thicker parts of the conductive paste are pressed near the corners of the semiconductor pellet and spread, making the thickness of the conductive paste uniform under the semiconductor pellet. can.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 5. Components in FIGS. 1 to 3 that are the same as those in FIG. 9 are given the same reference numerals. The explanation will be omitted. The structural feature of this embodiment is that a cylindrical body 8 for guiding the conductive paste outflow is fitted and fixed to the lower end of the nozzle 1'.

The cylindrical body 8 is a rectangular cylindrical body made of stainless steel or the like, which is inserted coaxially into the lower end of the nozzle 1' and removably fixed by means such as screws, and is made of stainless steel or the like to which the conductive paste 2 does not adhere. For example, a substantially cross-shaped paste guide groove 10 is formed. The lower end surface 9 is a concave spherical surface centered on the paste outlet 4 of the nozzle 1', and the paste guide grooves 10 extend from the paste outlet 4 at 90° intervals to near the four corners of the lower end surface 9, as shown in FIG. The four paste guide grooves 10a to 10d extending in all directions have the same shape and depth, and each bottom extends from the paste discharge port 4 with an inclined upward angle. Further, the lower surface 9 of the cylindrical body 8 is set to approximately the maximum size of the semiconductor pellet to be mounted.

Next, the conductive paste supplying operation according to the above embodiment will be explained together with the later semiconductor pellet mounting operation.

Lowering the nozzle 1' equipped with the cylindrical body 8,
As shown in FIG. 5, the cylindrical body 8 is brought into contact with the pellet mount section 5, and in this state, the paste discharge amount control section 3 causes the conductive paste 2 in the nozzle 1' to be discharged in a fixed amount from the paste discharge port 4. . Then, the discharged conductive paste 2' first hits the pellet mount part 5 and then passes through the four paste guide grooves 4a.
~4d, spreads to a location corresponding to the discharge amount, and adheres to the pellet mount portion 5. When the nozzle 1' and the cylindrical body 8 are pulled up, a substantially cross-shaped conductive paste 2' remains on the pellet mount portion 5, as shown in FIGS. 6 and 7.
This conductive paste 2' is applied to the paste guide groove 10.
Due to the slope of the bottom, the center part is thin and the four peripheral edges are thick.

After supplying the conductive paste in this way, as shown in FIG. 8, place the semiconductor pellet 7 on the conductive paste 2' on the pellet mount part 5 so that its four corners are closest to the four peripheral edges of the conductive paste 2'. Mount by pressing in the direction. At this time, semiconductor pellet 7
By pressing, the thick peripheral part of the conductive paste 2' spreads in the direction shown by the arrow in FIG. The thickness of the conductive paste underneath becomes uniform.

Further, when the size of the semiconductor pellet 7 changes, for example becomes larger, the amount of conductive paste discharged from the syringe 1 is increased in accordance with this change. Then, as shown by the chain lines in FIGS. 6 and 7, the shape of the conductive paste 2' supplied onto the pellet mount portion 5 becomes larger, and it is possible to sufficiently cope with changes in pellet size.

Note that the present invention is not limited to the above-mentioned embodiments, and in particular, the shape of the paste guide groove of the cylindrical body can be modified in various ways.

Effects of the invention According to the invention, the total amount of conductive paste supplied onto the pellet mount varies depending on the amount of conductive paste discharged from the syringe at one time, so it is highly adaptable to changes in the size of semiconductor pellets. Particularly, it is possible to provide a highly effective conductive paste supply device used when mounting a plurality of semiconductor pellets of different sizes on a hybrid IC substrate.
In addition, the thickness of the conductive paste supplied to the top of the pellet mount is smaller at the center and larger at the peripheral edges, so it is easy to apply the conductive paste to the same thickness all over the bottom of the semiconductor pellet when mounting the semiconductor pellet. This enables highly reliable semiconductor pellet mounting. Furthermore, since the method can be implemented simply by attaching the cylindrical body to a conventional syringe, it is possible to provide an equipment that is advantageous in terms of equipment investment and easy to implement.

[Brief explanation of the drawing]

1 and 2 are a side sectional view of a main part and a sectional view taken along line A-A of an embodiment of the present invention, FIG. 3 is a sectional view taken along line BB of FIG. 2, and FIG. The figure is a partially enlarged perspective view of the cylindrical body of the device shown in FIG. 1, FIG. 5 is a partially enlarged sectional view of the device shown in FIG. 1 during operation, and FIGS. A plan view of the conductive paste and a cross-sectional view taken along the line C-C.
FIG. 6 is a plan view of semiconductor pellets mounted on the conductive paste shown in the figure. FIG. 9 is a side sectional view of a main part of a conventional conductive paste supply device, and FIGS. FIG. 2 is a plan view of a semiconductor pellet. 1...Syringe, 1'...Nozzle, 2, 2',
2″...Conductive paste, 4...Paste discharge port,
8... Cylindrical body, 9... Lower end surface, 10... Paste guide groove.

Claims (1)

[Scope of utility model registration request] At the bottom end of the syringe that dispenses the conductive paste,
The syringe is characterized in that a cylindrical body having a lower end surface centered on the paste discharge port at the lower end and a paste guide groove extending with an inclined bottom in a star shape centered on the paste discharge port is attached to the lower end surface. conductive paste supply device.