JPS6242595A - printed wiring board - 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 Field of Industrial Application The present invention relates to a printed wiring board used in electronic equipment and the like.

When a printed wiring board on which conventional technical components have been mounted is soldered in a solder bath, preheating is performed before soldering to ensure good soldering properties. Particularly in the case of flow soldering using cream solder, this preheating is a major factor that influences the soldering properties.

Problems to be Solved by the Invention However, in conventional printed wiring boards, the preheating effect is often made uniform, and the preheating effect is often uniform, not only in the soldering area but also in the printed wiring board and even the mounting area. Preheating increases the overall temperature, even down to the electronic components inside. In particular, when heating at high temperatures during soldering, electronic components with low heat resistance may be destroyed, making it impossible to solder using a solder bath, and it is impossible to stop such component parts. It was customary to add it as an afterthought.

The present invention solves these problems with conventional products by reducing the temperature rise caused by preheating between the soldering part and its surrounding parts, and the soldering part and the soldering-related part. It is an object of the present invention to provide a printed wiring board that can prevent an excessive temperature rise of components having different heat resistance.

Means to Solve the Problems In order to achieve the above object, the present invention coats a printed circuit board with paints having different absorption rates of heat rays, and selects one by absorbing or reflecting heat rays such as near infrared rays during preheating. It is designed to suppress the temperature rise.

Therefore, according to the present invention, a paint that absorbs or reflects heat rays is applied depending on the shape and position of the mounted component or the shape of the soldered part, so that high temperature It is possible to selectively form a low-temperature section and a low-temperature section.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In Figure 1, 1 is a printed wiring board, 2 is a heat ray absorbing paint coated part coated with a paint that easily absorbs near infrared rays, and 3 is a heat ray reflective paint coated part coated with a paint that reflects heat rays. It is. 4 is a broken line in the cross-sectional view shown in FIG. 2(a). 5 is the part number of the printed wiring board.

Organic solvent-based paints such as road map ink and resist ink can be used as paints, and those colored black or dark green can be used to absorb heat rays, and those colored white can be used to reflect heat rays. Each can be used as follows.

In FIG. 1, the patterns of the paint application parts 2 and 3 are selected depending on the shape of the component to be mounted and the shape of the soldering part.

FIG. 2(a) is a sectional view of the above embodiment taken along the breaking line 4 in FIG. 1 in a mounted state. In the figure, 11 is the base material of the printed wiring board 1, 12 is the copper foil part, 13 is the cream solder applied for soldering, 14 is the soldered terminal part of the component to be mounted, and 16 is the component to be mounted on the board. An adhesive layer 16 for fixing and holding indicates a component to be mounted.

As shown in FIG. 2(a), the printed wiring board on which components are mounted is preheated by irradiating the surface opposite to the component mounting surface with hot rays.

FIG. 2(b) shows the temperature distribution of the component mounting surface after preheating.

This distribution is along the cut plane in Figure 2(a),
The temperature of the soldered terminal part 14, that is, the temperature of the part opposite to the part 2 coated with a paint that easily absorbs heat rays is higher than the other part, and the temperature of the component 16, that is, the part 3 coated with a paint that reflects heat rays is higher than the other part. It can be seen that the temperature on the opposite side is significantly lower than the other part.

In this way, according to the above embodiment, the preheating temperature distribution can be controlled by selectively applying paints having different heat ray absorption rates. That is, it is possible not only to increase the temperature of the soldering part, but also to prevent electronic components and the like having poor heat resistance from being excessively heated due to preheating. Therefore, unlike conventional products, in order to improve solderability, the temperature during preheating can be selectively increased only in the soldered part, and the temperature rise in other parts can be suppressed to prevent characteristic deterioration due to heat. be able to.

Still, in the above example, the paint No. 6 in FIG. 1 was the same as the heat-reflecting paint described above,
Although they are printed at the same time, it is also possible to use the same printing surface for printing product numbers, parts layout diagrams, etc. and for temperature control.

It is also clear that the temperature rise distribution can be arbitrarily selected by changing the type of paint and the shape of the coated area.

Effects of the Invention The printed wiring board of the present invention is selectively coated with a paint that absorbs or reflects heat rays, and it is possible to control the distribution of temperature rise when the printed wiring board is preheated by the heat rays. has advantages. Furthermore, this has the effect of ensuring the solderability of the components while suppressing excessive temperature increases for components with low heat resistance.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a printed wiring board according to an embodiment of the present invention, FIG. 2(a) is a cross-sectional view taken along the breaking line 4 in FIG. 1, and FIG. FIG. 2 is a temperature distribution diagram of the substrate surface. DESCRIPTION OF SYMBOLS 1... Printed wiring board, 2... Heat ray absorbing paint application section, 3... Heat ray reflective paint application section, 11
... Base material of printed wiring board 1, 12 ... Copper foil part, 13 ... Cream solder, 14 ...
・Soldering terminal part of the component, 16...Adhesive layer for fixing the component, 16...A・Body part of the component to be mounted. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure f-bp41Kn+D-2-a! Figure 2 f2-copper T, 5Jff lj-1-cream solder t4-~-zu date) Island 3-An p External line (b

Claims (1)

[Claims] A printed wiring board that has paints with different heat ray absorption rates selectively applied to the board surface to create different temperature distributions when heated by heat rays.