JPH0342894A - Packaging of semiconductor device - Google Patents

Abstract

PURPOSE:To supply the proper amount of solder with high accuracy by putting a solder paste that is applied in advance to a film on top of a printed wiring board (POB) and then, performing the transfer of a pattern. CONSTITUTION:A resist 9 consisting of a photosensitive resin is stuck to a film 8 consisting of a material which has poor fitting to a flux in a solder paste. Then, a pattern fitting into each land 2a on a POB 1 to which solder is to be supplied is exposed and developed on the resist 9 by photolithography and then, an opening 9a is formed at a part to be applied with the solder paste 5a. Subsequently, using the opening 9a as a mask, the solder paste 5a is applied on the opening 9a and then, the solder paste 5a is supplied only into the opening 9a. After that, the resist 9 is peeled off physically from the film 8 and a solder sheet 7 is prepared. The solder sheet 7 is bonded onto each land 2a after putting its sheet on top of each land so that its sheet is fit to the land. Subsequently, the film 8 of the solder sheet 7 is peeled off and each semiconductor device 4 is soldered to the solder paste 5a.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for surface mounting a semiconductor device on a printed circuit board, and in particular to a solder supply unit. [Prior Art] Fig. 6 shows a conventional semiconductor device. Equipment printed wiring board (hereinafter referred to as PO
FIG. 70 shows a 70-chart of the surface mounting process (referred to as B). FIGS. 7A to 7E are a perspective view and a side view showing each process corresponding to the above flowchart. In the figure, l
is the FOB, 2 is the wiring pattern on the FOB, 2a is the wiring pattern for mounting the semiconductor device FIT4, the part called land, 3 is the solder paste) 5a is the squeegee for printing, 6 is the metal mask, 5m is the printed It is a solder paste.

Next, the conventional technology will be explained. In the technique of soldering the semiconductor device i14 and chip components (not shown) onto the POB l, especially when mounting surface mount type components,
This is carried out according to the flowchart shown in FIG. As shown in Fig. 7, land 2 is soldered on POBI.
In the al1 minute, solder paste 5 consisting of solder, 7 lux, etc. is printed. For this printing, solder paste 5 is supplied onto a metal mask 6 with openings 6a made only in the areas where solder is needed, and the squeegee 3, which is a rubber-like spatula, is moved in the direction of the arrow to spread the solder paste 5. Print on wiring pattern recognition that requires soldering on POBI. Next, the semiconductor device @ 4 and chip components (not shown) to be mounted are aligned on the wiring pattern 2 by pattern recognition, etc.
Mount. After that, the solder paste (5a) was melted in a heating furnace using infrared*m+heat, etc., and the excess adhesive was removed in a cleaning process to complete the mounting.

[Problem to be solved by the invention]

In FIG. 8, the lead pitch P of the semiconductor device 4 is conventionally 0.8 u and 0.66 fl, which tends to be reduced as the packaging density improves.

With conventional solder paste printing methods, it is very important to improve printing accuracy and control the thickness of printed solder paste. For example, in order to print with high precision when P=0.4ff, the thickness of the metal mask 6 should be made thin, for example, 0.1 f.
The protrusion between wiring patterns must be eliminated by setting the width to less than l. However, by reducing the thickness of the metal mask, the weight of solder supplied to the wiring pattern 2a is reduced, so it is difficult to use a scale that cannot form an appropriate meniscus 5b of solder necessary for reliability as shown in FIG. There is a problem in that due to a defective attachment, an oven failure occurs in which the semiconductor device 4 and the wiring pattern 2a are not connected.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for mounting a semiconductor device that can accurately supply an appropriate amount of solder.

[Means to solve the problem]

In the method for mounting a semiconductor device according to the present invention, a sheet is used in which a cold cloth is applied with solder paste in advance on a mirror image of the area corresponding to the land of the POB, and this solder paste is applied in advance to #
The above-mentioned sheet coated with R cloth is brought into contact with a POB, transferred onto the POB, the sheet is then peeled off, and a semiconductor device is mounted on the solder paste portion by soldering.

[Effect]

By adjusting the thickness of the solder paste applied in advance, the solder sheet in this invention can be used with any solder paste key. Since the solder paste can be applied with high precision without any interference, it is possible to mount highly reliable semiconductor devices.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows each process in a flowchart. FIG. 2 is a side view showing each step corresponding to the above flowchart. 8th
The figure is a perspective view of the solder sheet 7. In the figure, l is P
OB, 2a is a wiring pattern for mounting the semiconductor device 4, 5
Reference character a is the transferred solder paste, 7 is a solder sheet, and 8 is a film of the solder sheet 7. Since each other part is the same as that of the conventional example, the same reference numerals are given and the explanation is omitted.

Same position as pattern 2a on POBI where solder should be supplied,
Solder sheet 7 coated with solder paste (5a) on the same pattern in advance is overlapped and adhered so as to match the land 2a on POBI (Figure 2 opening) 0 Then peel off the film 8 of solder sheet 7 (Figure 2) fart).

The semiconductor device Wt4 is soldered to this solder paste) 6a. An example of the method for producing the solder sheet 7 is shown in FIG. First, as shown in Fig. 4, a film 8 (Fig. 4 A) made of a material that is not compatible with the flasox in the solder paste is prepared.
A resist 9 made of photosensitive resin is pasted on top (fourth
Figure mouth). The film thickness of the resist 9 at this time is set to a film thickness corresponding to the amount of solder required for soldering. Next, a pattern that matches the land 2a on the POBI to which solder is to be supplied is exposed and developed on the resist 9 by photolithography, and the solder paste 5 is
Form an opening 9a in the area where a is to be applied (see Figure 4) Using this opening 9& as a mask, apply solder paste (5a) over it, and apply solder paste (5m) only inside the opening 9a. supply (Figure 4 2). After that, the resist 9 is physically peeled off from the film 8, and the solder sheet 7 is created (FIG. 4 E). Using the created solder sheet 7, pressure is applied according to the flowchart in FIG. Alternatively, transfer to the land 2a on the POBI by heating (temperature at which the solder does not melt), etc., peel off the film 8 from the material that is not compatible with the solder paste 5a, and apply only the solder paste 5a to the land 5a. leave on top.

Here, we have described a solder sheet coated with solder paste, but Fig. 5 shows another example of PO using a solder sheet in which molten solder is formed on a film.
A method of supplying solder to the land 2a on Bl will be explained.

A thin metal film 10 that is conductive and does not form an alloy with solder is formed on the film 8 (see Figure 5).

Apply a resist on top of this (Fig. 5 c) and create an opening 9.9a by photolithography (Fig. 5 2), and use the base metal 1O as a plating electrode to form solder in the opening 0 (Fig. 5). e).

Thereafter, the solder 5a is melted and solidified by a heat source, and then the resist 9 is removed (see FIG. 5). Using the thus obtained solder sheet 7, a solder layer 5a is formed on the land 2a by the steps shown in FIGS. 1 and 2, and a semiconductor device is mounted.

〔Effect of the invention〕

As described above, according to the present invention, since the pre-applied 1,000m paste is superimposed and transferred onto the POB, an appropriate amount of solder can be obtained, and a product with high precision can be easily obtained.

[Brief explanation of drawings]

FIG. 1 is a mounting flowchart of a semiconductor device according to the present invention, FIG. 2 is a side view showing an embodiment of the present invention, FIG. 8 is a perspective view showing an overall view of the solder sheet of the present invention, and FIG. 4 is a diagram showing the present invention. 5 is a side view and a perspective view showing one embodiment of the solder sheet producing method used in the present invention, FIG. 5 is a side view showing another embodiment of the solder sheet producing method used in the present invention, and FIG. 6 is a conventional technique. FIG. 7 is a perspective view and side view of each process corresponding to this flowchart, and FIG.
9 and 9 show the mounting state of a general semiconductor device, with FIG. 8 being a perspective view and FIG. 9 being a side view of the main parts. In the figure, 1 is a printed wiring board (POB), 2& is a wiring pattern, 4 is a semiconductor device, 5a is a solder paste, 7 is a solder sheet, and 8 is a film. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] When mounting a semiconductor device on a printed wiring board, as a method of supplying solder for soldering onto the wiring pattern on the printed wiring board, a sheet coated with solder in advance in the solder supply section is placed on the printed wiring board. Apply solder to the wiring pattern without using a metal mask by applying the solder paste, peel the film of the sheet from the printed wiring board after supplying the solder, and then solder the semiconductor device onto the solder area. A method for mounting a semiconductor device, characterized in that the semiconductor device is mounted by attaching the device.