JPH04254396A - Manufacture of high density mounted board - Google Patents

Abstract

PURPOSE:To enhance the reliability and productivity of soldering connection by printing solder paste on a connection pattern which connects each kind of semicnductor and electric component in such a fashion that it may cover each of the whole patterns, then heating them at a temperature which exceeds a melting point of solder and selectively forming a solder pattern on said connection pattern. CONSTITUTION:Organic solder or low temperature solder is printed on a rectangular-shaped paste pattern 7 on a semiconductor connection pattern 6 on a printed wiring board 5. A specified semoiconductive is fixedly installed to this board 5 on which the solder paste pattern 7 is printed. The solder is molten and electrically connected thereto. When the ogranic solder is heated at a temperature higher than 200 deg.C, the Cu and solder's Sn which form the connection pattern 6 produce a metal compound so that they may be connected to each other. Then low temperaturew solder produces a metal compound in a similay fashion. This construction makes it possible to enhance the solder connection properties and reliability as well.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to various high-density mounting boards in the field of information equipment, particularly a method for manufacturing high-density mounting boards using a solder printing method for connecting semiconductors and electrical components.

0002

2. Description of the Related Art High-density mounting boards, in which a large number of various semiconductors and electrical components are mounted on printed wiring boards, are used in both consumer and industrial fields. Specific examples include video movies, mobile phones, and personal computers. For television receivers as well, TV receivers have been commercialized that have built-in receiving circuit blocks for text broadcasting and satellite broadcasting as additional functions in addition to conventional video/audio circuits. For this reason, television receivers also use glass/epoxy multilayer boards with four to six layers, and various surface-mounted components such as electrolytic capacitors and chip resistors are automatically mounted on them.

[0003] Also, QFP with a pitch of 0.8 to 0.5 mm
type semiconductors and SO type semiconductors with a pitch of 1 to 2 mm are also mounted at the same time.

A method of manufacturing a high-density mounting board, which is an embodiment of the present invention, will be described below with reference to the drawings. Here, a manufacturing method for connecting a QFP type semiconductor onto a single-sided printed wiring board will be described. FIG. 4 shows an example of a board in which a solder paste pattern is screen printed on a semiconductor connection pattern on a conventional printed wiring board using the solder plate shown in FIG. As shown in FIG. 4, a semiconductor connection pattern 16 and a solder paste pattern 17 are formed on a printed wiring board 15. The printed wiring board 15 may be a single-sided or double-sided board such as a glass epoxy board or a ceramic board, and a multilayer board with 4 to 6 layers may be used depending on the purpose. The semiconductor connection pattern 16 is formed by etching copper foil laminated on the printed wiring board 1, and corresponds to the dimensions of the legs of the semiconductor component to be mounted. As shown in FIG. 4, the dimensions of screen printed solder paste pattern 17 may generally be smaller than semiconductor connection pattern 16. Moreover,
As shown in FIG. 4, the semiconductor connection pattern 16 and the solder paste pattern 17 are separated from each other, and it is necessary to print them with high precision. Solder paste pattern 1
No. 7 uses a material made of Sn/Pb eutectic solder.

On the other hand, FIG. 3 shows a solder paste pattern 17.
The structure of the screen plate 11 used for screen printing is shown. A plurality of holes 14 are provided in a metal 13 formed by pasting a thin stainless steel plate on the inside of a plate frame 12 by an etching method through which a material for a solder paste pattern 17 shown in FIG. 4 passes during screen printing. A screen plate 11 and a printed wiring board 15 are accurately aligned and fixed to a screen printing machine, and solder paste is printed under predetermined printing conditions to form a solder paste pattern 17.

[0006]

[Problems to be Solved by the Invention] However, in the manufacturing method of screen printing with the above-described configuration, solder printing is difficult to achieve in order to fine the pitch of the connection patterns of various semiconductors mounted on the printed wiring board 15. It is becoming impossible to cope with it. Furthermore, even with the connection pitch of the current semiconductor connection pattern 7 of 0.8 to 0.65 mm,
Printing defects of solder paste pattern 7 occur frequently. A semiconductor is mounted on such a printed wiring board 15,
When heat bonding is performed using a reflow method or the like, defects such as solder balls and solder bridges occur, resulting in poor connection. On the other hand, in terms of equipment, a high-precision screen printing machine with automatic recognition was required, resulting in high equipment investment costs and poor productivity.

[0007] The present invention solves these problems, and aims to provide a method for manufacturing high-density mounting boards using a highly accurate solder printing method that improves the reliability and productivity of solder connections. That is.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the method for manufacturing a high-density mounting board of the present invention provides a method for manufacturing a high-density mounting board of the present invention. A solder paste is printed on the solder, and then the solder is heated above the melting point of the solder to melt the solder and selectively form a solder pattern on the connection pattern. Furthermore, organic solder or low-temperature solder is used as the solder material.

[0009]

[Operation] The present invention uses the above-described high-density mounting board solder printing method to reliably and reliably connect the various semiconductors and electrical components to the connection patterns on the printed wiring board.
In addition, it is possible to connect with high productivity. Therefore, circuits made of various high-density mounting boards of video information equipment can be driven with high quality.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a high-density mounting board according to an embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show the structure of a method for manufacturing a high-density mounting board according to an embodiment of the present invention. As shown in FIG. 1, a thin stainless steel plate 2 attached to a soldering plate frame 1 is provided with four rectangular holes 3 corresponding to QFP type semiconductors. This hole 3 is
The thin stainless steel plate 2 is processed by an etching method or a laser processing method. The thickness of this thin stainless steel plate 2 is 0.
．． A thickness of 2 mm or less is desirable. Next, in Figure 2, Figure 1
The solder paste is screen-printed onto the semiconductor connection pattern 6 on the printed wiring board 5 using the solder plate 4 of FIG. As shown in Figure 2, organic solder or low temperature solder is applied to a rectangular solder paste pattern 7.
The thickness of these solder paste patterns 7 is set to about several to several tens of microns. As the organic solder material which is the solder material mentioned above, a tin compound of higher fatty acid is used. In addition, as for the low-temperature solder, unlike the conventional Sn/Pb eutectic solder, this example uses S
n/Pb/In or Sn/Pb/Bi is used. Figure 2
A predetermined semiconductor is fixed onto the substrate 5 on which the solder paste pattern 7 in the state shown in FIG.

Among these solder materials, organic solder can be heated in a reflow oven at a high temperature of 200° C. or higher to form an intermetallic compound between the Cu forming the connection pattern 6 and the Sn of the solder to form a connection. Intermetallic compounds are similarly created when using low-temperature solder materials.

The connection principle of the conventional Sn/Pb eutectic solder is the same as that of this embodiment, but since the surface tension of the solder material is small when it is melted, the connection pattern 6 is printed to cover the entire connection pattern 6 as shown in FIG. In this case, it cannot be formed separately from the connection pattern 6 during melting. When the solder material of the present invention is used, the solder is melted by high temperature heating and the wettability to the connection pattern is greatly improved, so that selective connection to the connection pattern can be reliably achieved.

Although this embodiment is an example in which a semiconductor is mounted, an electrical component such as an electrolytic capacitor may not be separated into two connection patterns, but the above-mentioned organic solder or low-temperature solder may be screen printed.

[0014]

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, it is no longer necessary to accurately print solder paste on a connection pattern with a fine pitch, and the solder passes through the screen of the frame. The shape of the hole for soldering becomes simpler, the time required to produce the soldering plate is shortened, and the cost is reduced. Furthermore, the productivity of the board is increased, and there are almost no solder connection defects, which improves the yield. Therefore, it will be possible to support even finer connection patterns that will become more detailed in the future.

[Brief explanation of the drawing]

[Fig. 1] A plan view of a solder plate according to an embodiment of the present invention.

[Figure 2]
Top view of a printed wiring board screen-printed with the same solder paste

[Figure 3] Plan view of conventional solder plate

[Figure 4] Plan view of a printed wiring board screen-printed with the same solder paste

[Explanation of symbols]

1 Solder plate frame 2 Stainless steel thin plate 3 holes 4 Solder version 5 Printed wiring board 6 Semiconductor connection pattern 7 Solder paste pattern

Claims (3)

[Claims] 1. Solder paste is printed on the connection patterns of a plurality of semiconductors and electrical components formed on a printed wiring board so as to cover the entire connection patterns, and is heated to a temperature higher than the melting point of the solder paste to form the connection patterns. A method for manufacturing a high-density mounting board by selectively forming a solder pattern thereon. 2. The method of manufacturing a high-density mounting board according to claim 1, wherein the solder paste material is printed to cover the entire connection patterns of a plurality of semiconductors and electrical components. 3. The method of manufacturing a high-density mounting board according to claim 1, wherein the solder paste material is printed to cover the entire connection patterns of a plurality of semiconductors and electrical components.