JPH06232527A - Printed board - Google Patents

Abstract

PURPOSE:To completely remove residual flux from the gap between components and a printed board by providing small holes for residual solvent between mounting patterns of electronic components. CONSTITUTION:An electrode part, which is located on both ends of each chip component to be placed, and conductive connection parts 11 and 11 are wired by a pattern 12 on a printed board 1. Small holes 13 are provided between the connection parts 11 and 11. The small holes 13 are provided in order to remove the residual flux solvent which is coated in advance between the chip component and the printed board 1 for prevention of defective soldering, and a cleaning fluid can be circulated. As a result, even when the solvent such as flux and the like remains between the electronic component and the printed board 1 after soldering, a cleaning liquid can be intruded easily, and the residual solvent in the gap between the printed board and the electronic component can be removed with certainty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board which constitutes high frequency equipment, electronic equipment and the like.

[0002]

2. Description of the Related Art Generally, when electronic components are soldered and fixed on a printed circuit board that constitutes a high frequency device or electronic device, the electronic components are applied on a cream solder applied according to a circuit pattern on the front surface side. The soldering process of melting and soldering the cream solder by correspondingly placing and then heating, and immersing in the molten solder with each lead part of the electronic component inserted in the lead insertion hole etc. And a soldering process for soldering.

In such a soldering process, foamed flux or the like is applied to the printed circuit board in advance so that the electronic parts and the solder become compatible with each other, and then each electronic part is placed and then heated or melted into the solder. Is being immersed.

[0004]

However, in the above soldering process, if the electronic component is a surface mount type chip type electronic component, the flux tends to remain attached to the gap formed between the electronic component and the printed board. There was such a problem. When the flux remains in this way, the capacitance of parts such as capacitors fluctuates, which causes a problem when a circuit such as a high-frequency device is assembled.

Therefore, in order to surely remove the flux remaining in the gap between the component and the printed circuit board, conventionally, the cleaning was carried out by using the chlorofluorocarbon, but the cleaning by the chlorofluorocarbon is tending to be totally abolished worldwide. , Chlorofluorocarbon alternative cleaning has come to be performed.

However, the CFC substitute solvent currently used does not have a remarkable cleaning ability like CFC, so that the flux easily remains in a slight gap between the component and the printed circuit board, and in order to completely remove it, Long cleaning was required. Therefore, development of means for removing residual flux at low cost is urgently needed.

[0007]

In order to solve the above-mentioned problems, the first printed circuit board of the present invention is characterized in that small holes for cleaning the residual solvent are perforated between the mounting patterns of the electronic parts.

Further, the second printed circuit board is characterized in that a slit for cleaning the residual solvent is formed between the mounting patterns of the electronic parts, and the third printed circuit board is a multilayer printed circuit board, It is characterized in that a slit for cleaning the residual solvent is formed between the mounting patterns of the electronic components on the front side substrate.

[0009]

In any of the above printed boards, even if solvent such as flux remains in the gap between the electronic component and the printed substrate after soldering, a small hole is formed in the gap formed between the mounting patterns of the electronic component. For example, a CFC substitute solvent for cleaning can easily penetrate through the slits or slits, and the residual solvent in the gap can be reliably cleaned and removed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view showing a part of a printed circuit board according to an embodiment of the present invention, and FIG. 2 is a line A--A of FIG.
It is a schematic sectional drawing along a line. Printed circuit board 1 shown
Is a substrate that constitutes, for example, a high-frequency device or an electronic device, and a chip component 2 such as a surface-mounted capacitor is mounted on the front surface side as an electronic component.

The printed circuit board 1 has, for example, connection portions 11 and 11 which are electrically connected to the electrode portions 21 and 21 at both ends of each chip component 2 to be mounted, and are wired by a mounting pattern 12. Then, the connection parts 11, 11
A small hole 13 for cleaning the residual solvent is formed between them. The small holes 13 are formed in order to wash and remove the residual flux solvent previously applied between the chip component 2 to be fixed by soldering and the printed circuit board 1 to prevent defective soldering with a washing liquid. The diameter D is, for example, about 1 to 3 mm so that the cleaning liquid can easily flow.

Further, the small hole 13 has at least the connecting portion 11,
When the chip component 2 is soldered and fixed onto the chip 11, if it is located in the gap between the chip component 2 and the printed circuit board 1,
The position of perforation is not particularly limited.

In the printed circuit board 1 having the small holes 13 for cleaning the residual solvent, for example, first, the mounting pattern 12 is first formed.
The cream solder 14 is applied to each of the connection parts 11 and 11 formed in the above, and the corresponding chip parts 2 are respectively placed and then preheated and held in a heating furnace or the like (not shown) to melt the cream solder, As shown in FIG. 2, the chip component 2 is fixed by soldering. At this time, in order to prevent defective soldering, the flux solvent in a foamed state which is previously applied to the printed circuit board 1 or the flux existing in the cream solder itself remains in the gap between the chip component 2 and the printed circuit board 1 and remains as it is. It tends to be in a state that cannot be removed.

Thereafter, in order to solder and fix the mounting pattern 12 on the back surface side of the printed circuit board 1 and each electronic component (not shown), the back surface of the printed circuit board 1 is immersed in a molten solder bath to solder the back surface side. Go and finish the soldering work. In this case, since the small holes 13 are minute holes, there is no concern that the molten solder will blow up inside the small holes 13 and be blocked.

When the flux solvent previously applied to the printed circuit board 1 is immersed in the cleaning solution for cleaning and removal, the cleaning solution flows through the small holes 13 and the chip component 2 and the printed circuit board 1 mounted on the front surface side. The flux solvent remaining in the gap between and can be reliably removed by washing. Therefore, even if the cleaning power of the cleaning liquid that substitutes for CFCs, which has a high cleaning power but is environmentally problematic, is weak, the small holes 1
3 makes it possible to make good contact with the flux solvent remaining in the gap between the chip component 2 and the printed circuit board 1, and to remove the flux solvent by washing in a short time.

In this way, the flux solvent remaining in the gap between the printed circuit board 1 and the chip component 2 mounted on the front surface side of the printed circuit board 1 is reliably removed by the cleaning liquid as a CFC substitute. Since the mounted chip component is a capacitor or the like, and the problem that the capacitance is changed by bridging the electrodes due to the residual flux in the gap with the printed circuit board 1 is solved, reliability is high if it is a high frequency circuit board such as a VCO. Is increased.

The printed circuit board 3 shown in FIG. 3 has slits 4 for cleaning the residual solvent formed between the connecting portions 11 of the respective chip components 2. Even with such a printed circuit board 3, if the flux solvent remaining after the soldering work is washed with a washing solution, as with the printed circuit board 1, the chip component 2 and the printed circuit board 3 are removed.
The flux solvent remaining in the gap between and will be surely contacted and cleaned. In addition, when the slit 4 is formed, a large amount of cleaning solution flows into the above-mentioned gap and is easily discharged on the contrary, so that the cleaning solution can be removed more reliably.

Further, the printed circuit board 5 shown in FIG. 4 is a printed circuit board having a multi-layer structure, in which a slit 6 is formed between the connecting portions 11, 11 of each chip component 2 of the substrate body 51 on the front surface side. Even with this printed circuit board 5, the flux solvent remaining in the gap between the chip component 2 and the substrate main body 51 can be reliably removed by cleaning in the same manner as above, and the characteristics of each component do not change and the multilayer structure is highly reliable. It becomes the printed circuit board 5 of the structure. Here, the slit 6 is formed in the substrate main body 51.
It is preferable to extend it to the surroundings because the cleaning solvent can flow more reliably.

Since the gas contained in the flux is apt to cause defective soldering, the small holes 13 or the slits 4 and 6 formed in the printed circuit boards 1, 3 and 5 are used to remove the gas. Therefore, more reliable soldering work can be provided.

[0021]

As is apparent from the above description, in the printed circuit board of the present invention, even if a solvent such as flux remains in the gap between the electronic component and the printed circuit board after soldering,
The cleaning solvent can easily enter through the small holes or slits formed between the mounting patterns of the electronic components, and the residual solvent in the gap between the printed circuit board and the mounted electronic components can be reliably cleaned and removed. This has the effect of improving the reliability of each electronic component.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a part of a printed circuit board according to a first invention.

FIG. 2 is a schematic cross-sectional view taken along the line AA of FIG.

FIG. 3 is a schematic perspective view showing a part of a printed circuit board according to a second invention.

FIG. 4 is a schematic perspective view showing a part of a printed circuit board according to a third invention.

[Explanation of symbols]

 1,3,5 Printed circuit board 2 Electronic component (chip component) 4,6 Slit 12 Mounting pattern 13 Small hole

Claims (3)

[Claims] 1. A printed circuit board having small holes for cleaning a residual solvent between the mounting patterns of electronic parts. 2. A printed circuit board having slits for cleaning a residual solvent formed between mounting patterns of electronic parts. 3. A printed circuit board having a multi-layer structure, characterized in that a slit for cleaning a residual solvent is formed at least between mounting patterns of electronic components on the front surface side board.