JPS59182594A - Method of carrying printed board of chip carrier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for mounting a chip carrier on a printed circuit board, and more particularly to a method for accurately mounting a leadless chip carrier at a predetermined position on a printed circuit board.

tb+ Conventional technology and problems With the rapid development of electronic devices such as computers.

There has been an increasing demand for higher density and smaller packaging of electronic components in electronic devices. In particular, the degree of integration of semiconductor integrated circuits has increased further, chip carriers using ceramic substrates have been put into practical use, the number of terminals has increased, and the pitch has become smaller.

In order to mount the above-mentioned chip carrier on a printed circuit board, its position has conventionally been determined based on the external shape of the ceramic substrate of the chip carrier. That is, as shown in the perspective view of FIG. 1, a pattern P indicating the four corners of the ceramic substrate corresponding to the chip carrier 3 is formed in advance on the surface of the printed circuit board 4 at the position where the chip carrier 3 is to be mounted. The chip carrier 3 is positioned and mounted according to the pattern visually or using a low magnification microscope (not shown in the figure).
A method is adopted in which the pads (not shown) of the external connection terminals 2 of the chip carrier disposed on the bottom surface of the chip carrier are placed on the pads 5 on the printed circuit board Fj, 4 so as not to shift.

However, in reality, the external shape of the ceramic substrate of the chip carrier often does not have accurate dimensions with respect to the positions of the pads of the external connection terminals 2, making it difficult to locate the pads. This is especially true in the case of a chip carrier having a high density of I10 terminals as described above.

Further, pads 5 of a printed circuit of four examples of printed circuit boards when a chip carrier 3 having external connection terminals 2 on the side surface of a chip substrate 1 as shown in FIG. 2(a) is mounted on a printed circuit board 4.
For example, it may protrude slightly from the mounting surface of the chip substrate 1 as shown in the figure.

At this time, the knob carrier 3 can be correctly positioned on the pad 5 by visual inspection.

However, with the increasing density of semiconductor integrated circuit devices, in the chip carrier shown in Fig. 2+a), the location where external connection terminals 2 can be arranged is limited to the side surface of the chip substrate 1, so the number of external connection terminals 2 is limited to 80 at most. As a result, a chip carrier of the type shown in FIG. 2(b), which makes full use of the back surface of the chip substrate 1, has been adopted.

In this type of 1,000-knob carrier, a large number of conductive parts called vias 6 containing tungsten powder or the like are formed through the chip substrate 1, and where the tip reaches the back surface of the chip board 1, a 5n called a hump 7 is formed. - A hemispherical connection portion made of a Pb-based metal is provided. When the thousand-knob carrier is mounted on the printed circuit board 4, as is clear from FIG. 1, the pad 7 on the other side of the hump 7 is hidden by the chip board 1 and cannot be seen.

As mentioned earlier, using the method shown in FIG. 1, the outline of the chip board 1 is located using the outer edge of the chip board 1 as a reference and the 5 groups of knobs on the printed board 4 as a reference. It is also possible to use the method of aligning the ζ chip board 1 using the mark P that indicates the position where the Because they are transferred one after another, accuracy does not improve and the work is complicated and inefficient. A simpler and more effective method for positioning a thousand-knob carrier has been long awaited.

(C) Object of the Invention The present invention has been made in view of the above-mentioned points, and the present invention has been made in view of the above-mentioned points. The aim is to provide a method for mounting the device without shifting.

(d) Structure of the Invention It is an object of the above-mentioned invention to move a chip carrier having a plurality of nozzles to a predetermined nozzle of a printed circuit of a printed board.
7. When mounting on the board, select at least three humps of the chi knob carrier and place a on pads on the printed board corresponding to the humps.

A chip characterized in that the position of the tip 7 carrier on the printed board is determined by checking the presence or absence of electrical continuity for all pairs between the selected hump and the pad. This is easily achieved by the printed board mounting method of the carrier.

+e+ Embodiments of the Invention Examples of the present invention will be described below with reference to the drawings. FIGS. 3A and 3B are plan views respectively showing the back surface of the chip substrate 1 of the chip carrier 3 used in this embodiment and the corresponding mounting surface on the printed board 4. FIGS.

The hump 7 on the back surface of the chip substrate 1 selected for positioning is indicated by a black circle. As is obvious from a geometrical point of view, it is best to select the four corners of the back surface of the chip substrate 1. Theoretically, three of the four corners determine the positioning of the chin 1 and the substrate 1, so three is sufficient. The selected positioning amplifiers 7a are wired on the chip substrate 1 and short-circuited to each other.

The pattern of PyF'5a on the printed board 4 shown in FIG. 3B, which corresponds to the hump 7a, is made as small as possible compared to the other patterns of P7D5. ff should be approximately 0.3 mm. Of course, the center position requires precision. The smaller the size of this pattern, the more accurate the positioning will be. In high-density packaging as in this example, the printed board 4 is a multilayer printed board, and each pad 5.5a shown in FIG. 5 is connected to an inner layer of the printed board 4.

It is usually not visible from the front.

The method for mounting the chip carrier 3 follows the following steps. 12
1J et al., printed board 40 butt 5 was coated with solder paste by screen printing method, while chinobu carrier 3 was coated with solder paste.
Pre-solder the hump 7.

Next, the chip carrier 3 is placed at a predetermined position on the bat 5 corresponding to the bumps 7 with the back surface of the chip 1 substrate I of the chip carrier 3 facing the printed board 4. At this time, electrical continuity between three or four four corner bands 5a for one positioning is tested.

As mentioned above, the hump on the chip carrier 3 side is short-circuited in advance, so if the bumps 7a and butts 5a are aligned, there will be continuity between the bumps 7a.
It can be confirmed that the positioning is performed correctly. Since this positioning method does not involve visual inspection, it does not depend on the skill level of two workers, so the reliability of the work is improved and the time required for each work can be shortened.

For fixing the chip carrier 3 to the printed circuit board 4, leave it in position 1 and apply the aforementioned solder paste by blowing hot air onto it.
g and solder. So-called riff. -Easy to do by law.

FIG. 4 is a modification showing another positioning method.

In the method described above, a part of the nap carrier and the hump and buff for wiring connection of the printed circuit board were selected and used for positioning the chip carrier. A dedicated connection means is provided.

That is, as shown in FIG.
A positioning pattern 8 is formed in place of a.
As shown in Fig. 4 fb), three or four positioning bars 7 are provided on the printed board 4 side, and positioning can be performed by making sure that they are all electrically conductive. It is clear from the diagram that this is possible. At this time, although not shown in Figure 5, there are 1 (hard) terminals on the chip carrier side for checking electrical continuity to confirm positioning, and 4 on the printed board side.
Fig. 5 Bat 10 with a pattern like (al, (bl)
It is obvious that if this is provided on the printed board 4, only one positioning terminal on the printed board 4 side is required.

FIG. 6 is an explanatory diagram showing the shape and position of the positioning pattern lL12 on the chip board 1 side and four examples of printed boards. is the loop pattern 12 on the printed board 4 side.
Therefore, one positioning operation is completed by confirming that there is no electrical continuity between the patterns LL12.

It is possible to make the pattern for positioning the chip board 1 on the printed circuit board 4 more complex and in large numbers according to the required accuracy.

This is something that can be easily inferred.

ff) Effects of the Invention As is clear from the above explanation, if the mounting method according to the present invention is adopted, a chip carrier of a semiconductor integrated circuit having a high density of external terminals can be mounted on a bat on the printed circuit board. It can be mounted accurately and easily without any problems, improving the quality of the printed board.

This has the effect of reducing wiring costs.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the conventional method of mounting a chip carrier on a printed circuit board, and Figure 2 is a diagram showing the connection 4 of the chip carrier.
FIG. 3 is a plan view showing the position of a butt and hump for positioning confirmation used in an embodiment of the above method based on the present invention; FIG.
FIGS. 5 and 6 are plan views showing examples of patterns of dedicated connection portions for determining the position of use. 2 is a chip board, 2 is an external connection terminal, 3 is a chip carrier, 4 is a printed board, 5 is a pad, 6 is a via, 7 is a hump, and 8 is a positioning pattern. 9 indicates a positioning pattern, and 10.1L12 indicates a modified example of the positioning pattern.

Claims (2)

[Claims] (1) When mounting a chip carrier carrying a semiconductor integrated circuit and having a plurality of humps as external connection means on a predetermined band of a printed circuit on a printed board. Select at least three bumps of the chip carrier, place them on pads on the printed board corresponding to the humps, and place one bump on each of the selected bumps and the pad for all pairs. A method for mounting a chip carrier on a printed board, characterized in that the position of the chip carrier on the printed board is determined by checking the presence or absence of electrical continuity of each chip carrier. (2) At least 3 (11iI) positioning contact portions and terminals connected to the contact portions are formed on the back surface of the chip substrate of the chip carrier on which the bumps are arranged, and the printed board corresponds to the contact portions. Provide a groove (for positioning) on the top,
The chip carrier according to claim 1, wherein the chip carrier is positioned by checking the presence or absence of electrical continuity between the corresponding contact portions and the positioning band. How to mount the printed board.