JPH03235393A - Printed wiring board - Google Patents

Abstract

PURPOSE:To always perform temperature measurement at the same places and to make possible a heat treatment of a printed wire board under fixed conditions by a method wherein land pads for temperature measurement use are provided on at least one surface of the printed wiring board. CONSTITUTION:Land pads 1 for temperature measurement use are previously provided on the central parts of both surfaces of a multilayer printed wiring board 3 for temperature measurement use, which is transferred by a conveyor for transfer use to a direction 4 in a heating furnace, in such a way that the land pads 1 are provided in the center in the direction intersecting orthogonally to the direction 4 of both surfaces and on both sides of the centers, the individual pads 1 are provided with a land pad 2 with a hole applied a through-hole plating and the holes applied a through-hole plating of the pads 2 are connected to an internal layer land. By this constitution, variation in a heat treatment of the board 3 to be treated on the same treatment condition can be prevented by applying a thermocouple to the pads 1 on the surface when temperature conditions of reflow soldering, for example, are set, to the pads 1 on the rear when temperature conditions of flow soldering and at the time of hardening of a resist are set and to the pads 2 as one for setting the temperature conditions of these reflow and flow solderings and at the time of hardening of the resist.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to printed wiring boards.

(Prior art) Conventionally, during flow soldering and reflow soldering of printed wiring boards, and when curing resist coated on the surface with ultraviolet rays,
In order to measure the heating temperature of the heated printed wiring board and check whether it is being processed at the specified temperature, a printed wiring board of the same shape is printed for temperature measurement before heat treatment of the printed wiring board that becomes the actual product. Each lot of wiring boards is passed through a furnace together with a conveyor, and a thermocouple is placed on the surface of the printed wiring board to measure and confirm.

(Problem to be Solved by the Invention) However, with conventional printed wiring boards where temperature is measured using this method, even if the same printed wiring board is used for temperature measurement, the thermocouples may not be applied properly due to differences in the number of people measuring the temperature. If the locations are different, there will be variations in the corrected furnace temperature based on the results, and there is a risk that the quality of the product will vary.

Therefore, although each person taking the measurement is careful to place the tip of the thermocouple at a predetermined position, there are still variations in position due to visual inspection.

Therefore, an object of the present invention is to obtain a printed wiring board that can be easily heat-treated under constant conditions regardless of the manufacturing lot or the operator.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a printed wiring board that is conveyed in a heating furnace by a conveyor and heated, by providing a land pad for temperature measurement on at least one side of the printed wiring board. This is a printed wiring board that can be easily heat-treated under constant conditions by always measuring the temperature at the same location regardless of differences in manufacturer or lot.

(Example) Hereinafter, one example of the printed wiring board of the present invention will be described with reference to the drawings.

In FIG. 1, a multilayer printed wiring board 3 for temperature measurement is conveyed in a heating furnace (not shown) by a conveyor (not shown) in the direction of arrow 4. Land pads 1 for temperature measurement are provided in advance on both sides of the printed wiring board 3, and land pads 2 with through-hole plating holes are provided inside the land pads 1 on both sides and on the front side of the center land pad 1, respectively. The through-hole plating of this land pad 2 with through-hole plating holes is connected to a land (not shown) on the inner layer.

In the printed wiring board 3 configured in this way, the land pads 1 on the front surface are used to set temperature conditions for reflow soldering, and the land pads 1 on the back surface are used to set temperature conditions for flow soldering or resist curing. When setting the land pads 2, thermocouples for temperature measurement are applied to set the temperature conditions during reflow soldering, flow soldering, and resist curing, respectively, so that the printed wiring board should be subjected to the same processing conditions. Since it is possible to prevent variations due to measurement personnel, lots, type of printed wiring board, etc., the printed wiring board can always be heated under the same conditions to obtain a constant quality.

In the above embodiment, the land pad 2 may be omitted if necessary.

FIG. 2 is a diagram showing another embodiment of the printed wiring board of the present invention.

In the same figure, the left end of a multilayer printed wiring board 5 for temperature measurement, which is conveyed by a conveyor (not shown) in a heating furnace (not shown) in the direction of an arrow 4, has a rectangular temperature measurement land soldered to the center and both sides. A land pad 7 for use with a through-hole plated land pad 6 adjacent to the land pad 6 with square-shaped through-holes on both sides.
are provided for each.

In this case, as in the case of FIG. 1, the printed wiring board can be heated accurately under the same conditions regardless of the operator or manufacturing loft.

In addition, in the above embodiment, the land pad is 1°2.6,
7 has been explained in the example in which it is provided at the center of the printed wiring board and at the rear with respect to the conveyance direction, but it may also be provided at the upstream end in FIG. Furthermore, although the example has been described in which the holes are provided at three locations in total at the center and both sides, the number may be provided at one location, two locations, or four locations depending on the size of the external shape of the printed wiring board.

Furthermore, although the shapes of the land pads 1 and 6 have been explained using circular and square examples, they may be oval or polygonal.

Further, in the above embodiment, the land pad 1 and the land pad 2 with through-hole plating holes are formed on both sides, but the land pad 1 may be formed only on one side.

〔Effect of the invention〕

As described above, according to the present invention, in a printed wiring board that is transported and heated in a heating furnace by a conveyor, a land pad for temperature measurement is provided on at least one side of the printed wiring board, so that the temperature measurement point is always the same. Therefore, you can obtain printed wiring boards that can be heated at the same temperature regardless of the operator or the manufacturing loft.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the printed wiring board of the present invention, and FIG.
The figure is a diagram showing another embodiment of the printed wiring board of the present invention. 1... Land pad 2... Land pad with through hole plating hole 3...
printed wiring board

Claims (1)

[Claims] 1. A printed wiring board that is conveyed and heated in a heating furnace by a conveyor, characterized in that a land pad for temperature measurement is provided on at least one side of the printed wiring board.