Manufacturing method of over reflow soldering temperature measuring board

For the multi variety and small batch production mode, most enterprises use the general temperature curve in order to simplify the workload of setting the temperature curve, that is, some PCBAs with similar thermal characteristics are welded with the same temperature curve. At this time, the test and setting of temperature curve must determine the representative PCBA for test. Including the size and thickness of PCB shape and representative device packaging. Among them, the most key is to have the characteristic of representativeness. We usually call this representative PCBA "temperature measuring plate".

In order to obtain accurate and effective furnace temperature curve, whether the production of temperature measuring plate can accurately reflect the effectiveness and accuracy of temperature curve of reflux furnace becomes very critical, so how to make qualified temperature measuring plate?

1、 Selection principle of temperature measuring board

1. PCBA completely consistent with the tested product is preferred for temperature test

2. If there is no consistent, the temperature test shall be carried out in the place of the one with the same plate thickness and the same size of key test devices.

3. If there is no BGA complex device on the product, the product can be used for temperature test.

2、 Selection of temperature measuring points

1. It is defined according to the layout and size of the devices on the board, the direction of entering the reflow furnace and the relationship between the width of the board and the reflow track

Selection principle of temperature measuring points.

2. Selection of the hottest spot (left in and right out of the furnace) this rule considers that the board is cool before and hot after. It is considered that the hot spot of the board is the breeze blowing on the upper right corner of the board.

3. Selection of the coldest point: according to the above estimation, the coldest point of the board is the device in the lower left corner of the board entry direction.

3、 Selection of temperature measuring points

1. Thermocouple temperature range: - 200 degrees - 400 degrees, with accuracy of plus or minus 1.5 degrees at 200-250 degrees. The thinner the temperature measuring wire, the more sensitive it is, but it is not durable.

4、 Fabrication of temperature measuring probe

1. The temperature measuring point is the welding head led out by the lead wire. The thermocouple head shall be butted against the temperature measuring line and welded with high-temperature tin wire.

2. Cover the surrounding area with red glue and only expose the probe.