TWI820872B - Ir-reflow temperature sensing system - Google Patents

Abstract

An IR-reflow temperature sensing system includes an infrared reflow device, a temperature sensing unit, an ambient temperature sensing unit and a reflow temperature calculation unit. The infrared reflow device reflows a semiconductor device, the temperature sensing unit is used for sensing the temperature of the upper surface of a chip and outputting a temperature sensing signal, the ambient temperature sensing unit is used for sensing the temperature of the environment where the infrared reflow device is located and outputting an ambient temperature sensing signal. The reflow temperature calculation unit receives the temperature sensing signal and the ambient temperature sensing signal, and the reflow temperature calculation unit calculates a reflow temperature on the lower surface of the chip based on the temperature sensing signal and the ambient temperature sensing signal temperature.

Description

Infrared reflow temperature detection system

The invention relates to a reflow temperature detection system, and in particular to an infrared reflow temperature detection system.

The reflow soldering (reflow) process is a semiconductor process that uses a heating system to heat the joining solder between two electronic components to melt the joining solder and permanently join the two electronic components. Common reflow heating systems include hot air reflow systems, Laser reflow system and infrared reflow system. The hot air reflow system uses hot air to heat the inside of the reflow oven to melt the joining solder. The advantage is that the heating speed is fast and the cost is low. However, because the hot air heats the entire inside of the reflow oven, it is not suitable for thin electronic components. It may cause warpage and damage. The laser reflow system uses laser to heat the joint solder or electronic components. The advantage is that the heating range is small, but the disadvantage is that the heating speed is too fast and difficult to control and the cost is high. Infrared reflow systems use infrared rays to heat joint solders or electronic components. Compared with laser reflow systems, they are lower in cost, have a wider irradiation range and have a more moderate heating speed. However, infrared reflow systems are used in coatings. In the crystal structure, infrared rays must be irradiated on the back side of the chip and then transmitted to the bonding solder on the front side of the chip. This makes it difficult to control the reflow temperature at which the infrared reflow system actually heats the bonding solder.

The main purpose of the present invention is to use the temperature sensing unit to sense the temperature of the upper surface of the chip and the ambient temperature sensing unit to sense the ambient temperature. The reflow temperature calculation unit can use the temperature of the upper surface of the chip and the ambient temperature to calculate the temperature of the lower surface of the chip. The surface reflow temperature of the connector is used to estimate the current actual reflow temperature of the connector.

An infrared reflow temperature detection system of the present invention includes an infrared reflow device, a temperature sensing unit, an ambient temperature sensing unit and a reflow temperature calculation unit. The infrared reflow device is used to perform inspection on a semiconductor device. Reflow, the semiconductor device has a substrate, a chip and a plurality of connectors. The substrate has an active surface. The chip has an upper surface and a lower surface. The lower surface faces the active surface. The connectors are located on the substrate. and the chip, and the two ends of each connecting member are respectively connected to the active surface of the substrate and the lower surface of the chip, the temperature sensing unit is used to sense the temperature of the upper surface of the chip, and the The temperature sensing unit outputs a temperature sensing signal. The ambient temperature sensing unit is used to sense the temperature of the environment where the infrared resoldering device is located, and the ambient temperature sensing unit outputs an ambient temperature sensing signal. The reflowing device The temperature calculation unit is electrically connected to the temperature sensing unit and the ambient temperature sensing unit to receive the temperature sensing signal and the ambient temperature sensing signal, and the reflow temperature calculation unit uses the temperature sensing signal and the environment The temperature sensing signal calculates a reflow temperature of the lower surface of the chip.

The temperature sensing unit and the ambient temperature sensing unit of the present invention respectively sense the temperature of the upper surface of the chip and the environment where the infrared reflow device is located, and calculate the temperature of the chip through the reflow temperature calculation unit. The reflow temperature of the lower surface can be accurately grasped by the heating conditions of the connecting parts, thereby improving the yield rate of the reflow process.

Please refer to Figure 1, which is a block diagram of an infrared reflow temperature detection system 100 according to a first embodiment of the present invention. The infrared reflow temperature detection system 100 includes an infrared reflow device 110 and a semiconductor device. 120. A temperature sensing unit 130, an ambient temperature sensing unit 140 and a reflow temperature calculation unit 150.

One of the light sources 111 of the infrared resoldering device 110 generates heating light IR to resolder the semiconductor device 120 . Please refer to Figure 2 for a schematic diagram of the infrared resoldering device 110 resoldering the semiconductor device 120 . In this embodiment, , the semiconductor device 120 has a substrate 121 , a chip 122 and a plurality of connectors 123 . The substrate 121 has an active surface 121a. The chip 122 has an upper surface 122a and a lower surface 122b. The upper surface 122a faces the light source 111 of the infrared reflow device 110, and the lower surface 122b faces the active surface 121a. The connectors 123 are located between the substrate 121 and the chip 122, and two ends of each connector 123 are respectively connected to the active surface 121a of the substrate 121 and the lower surface 122b of the chip 122. The substrate 121 can be a ceramic substrate, a plastic substrate, a metal substrate, a tape and reel substrate, a silicon wafer or a silicon chip, and the connectors 123 can be solder balls, solder bumps or The invention is not limited by the types of metal bumps, the substrate 121 and the connectors 123 .

The heating light IR emitted by the infrared reflow device 110 irradiates the upper surface 122a of the wafer 122 for heating, and conducts heat energy to the lower surface 122b through the wafer 122 to reflow the connectors 123. Preferably, the base plate 112 used by the infrared reflow device 110 to carry the substrate 121 also heats the substrate 121 to prevent the substrate 121 from warping due to uneven heating. Preferably, the infrared resoldering device 110 also has a mask (not shown), the mask is disposed between the wafer 122 and the light source 111 of the infrared resoldering device 110, and the mask has a plurality of An opening allows the heating light IR to pass through, so that the infrared reflow device 110 can heat a local part of the semiconductor device 120. For example, the opening of the mask only allows the heating light IR to irradiate the upper surface 122a of the wafer 122. , and only the upper surface 122a of the wafer 122 is heated, thereby avoiding damage to other parts of the semiconductor device 120 due to heating.

Please refer to Figures 1 and 2. The temperature sensing unit 130 is used to sense the temperature of the upper surface 122a of the chip 122, and the temperature sensing unit 130 outputs a temperature sensing signal Ts. In this embodiment, The temperature sensing unit 130 is an infrared thermometer and can directly measure the temperature of the upper surface 122a of the chip 122.

Please refer to Figures 1 and 2. The ambient temperature sensing unit 140 senses the temperature of the environment where the infrared reflow device 110 is located, and the ambient temperature sensing unit 140 outputs an ambient temperature sensing signal Te. In this embodiment, , the ambient temperature sensing unit 140 is a digital thermometer and can directly output the digital ambient temperature sensing signal Te.

Referring to Figure 1, the reflow temperature calculation unit 150 is electrically connected to the temperature sensing unit 130 and the ambient temperature sensing unit 140 to receive the temperature sensing signal Ts and the ambient temperature sensing signal Te, and the feedback The soldering temperature calculation unit 150 calculates a reflow temperature Tr of the lower surface 122b of the chip 122 based on the temperature sensing signal Ts and the ambient temperature sensing signal Te. In this embodiment, the reflow temperature calculation unit 150 is an electronic computer and has a reflow temperature calculation equation inside. The reflow temperature calculation unit 150 combines the temperature sensing signal Ts and the ambient temperature sensing signal Te. The reflow temperature Tr can be obtained by substituting it into the reflow temperature calculation equation.

The reflow temperature calculation equation is calculated by first measuring the temperature sensing signals Ts, the infrared echo of multiple pens on the upper surface 122a through the temperature sensing unit 130, the ambient temperature calculation unit 140 and a thermocouple 160. After obtaining the temperature data of the ambient temperature sensing signal Te of the environment where the soldering device 110 is located and the lower surface temperature Tb of the lower surface 122b of the wafer 122, the reflow temperature calculation unit 150 obtains the temperature data through regression analysis. The reflow temperature calculation equation.

Since the reflow temperature calculation equation is obtained through regression analysis based on the actual measured temperature data, during the actual reflow process, the reflow temperature calculation unit 150 combines the temperature sensing unit 130 and the ambient temperature. The temperature sensing signal Ts and the ambient temperature sensing signal Te sensed by the sensing unit 140 are substituted into the reflow temperature calculation equation to obtain different temperature sensing signals Ts and the ambient temperature sensing signal Te. The reflow temperature Tr is below to ensure that the connectors 123 can be reflowed according to the set temperature curve.

In addition, although the lower surface temperature Tb of the lower surface 122b of the wafer 122 can be measured using the thermocouple 160, the circuit design of the thermocouple 160 must match the layout of the wafer 122, resulting in the production of the thermocouple 160. The cost is high and cannot be applied to all semiconductor devices. Therefore, this embodiment can only use the thermocouple 160 when calculating the reflow temperature calculation equation, which can reduce the cost required to calculate the reflow temperature Tr.

In another embodiment, if the reflow temperatures provided by the infrared reflow device 110 at different heating times and different input powers are considered, first through the temperature sensing unit 130 , the reflow temperature calculation unit 150 and the thermoelectric The couple 160 measures the temperature sensing signal Ts of the upper surface 122a of the chip 122 under different heating times and different input powers of the infrared reflow device 110, and the ambient temperature sense of the environment where the infrared reflow device 110 is located. After measuring the signal Te and the lower surface temperature Tb of the lower surface 122b of the chip 122, the reflow temperature calculation unit 150 performs regression analysis on the data to obtain the reflow temperature calculation equation.

In addition, please refer to Figure 2. Since the thickness W of the wafer 122 will also affect the conduction speed of heat energy, it is preferable that the reflow temperature calculation unit 150 performs regression analysis to obtain the reflow temperature calculation equation. Also included is the thickness W of the wafer 122 . That is, when the reflow temperature calculation unit 150 uses regression analysis to obtain the reflow temperature calculation equation, it also takes into account the temperature signals of the wafer 122 with different thicknesses W, so that it can more accurately calculate the wafers with different thicknesses. The reflow temperature Tr of 122°C.

Please refer to Figure 3, which is a second embodiment of the present invention. The difference from the first embodiment is that the infrared reflow temperature detection system 100 also includes a power measurement device 170 and an optical power meter 180. The power measuring device 170 is used to measure an actual power Pa of the infrared resoldering device 110 , and the optical power meter 180 is used to measure an illumination intensity Lx of the heating light IR emitted by the infrared resoldering device 110 . In order to more accurately calculate the reflow temperature Tr of the lower surface 122b of the wafer 122, the reflow temperature calculation unit 150 of this embodiment adds the infrared reflow device 110 when regression analyzing the reflow temperature calculation equation. The actual power Pa and the illumination intensity Lx of the heating light IR make the reflow temperature calculation equation include the actual power Pa and the illumination intensity Lx, which can further improve the accuracy of the reflow temperature Tr.

In addition, since the light source 111 of the infrared reflow device 110 may have degradation problems after long-term use, preferably, in this embodiment, the power measuring device 170 and the optical power meter 180 are measured separately. Comparing the actual power Pa and the light intensity Lx with the rated power and maximum light intensity of the power measuring device 170 can be used to determine the usage efficiency of the power measuring device 170 and serve as a basis for whether to replace the light source 111 .

The temperature sensing unit 130 and the ambient temperature sensing unit 140 of the present invention respectively sense the temperature of the upper surface 122a of the chip 122 and the environment where the infrared reflow device 110 is located, and use the reflow temperature calculation unit 150 calculates the reflow temperature Tr of the lower surface 122b of the wafer 122, so as to accurately grasp the heating conditions of the connectors 123, thereby improving the yield of the reflow process.

The protection scope of the present invention shall be determined by the appended patent application scope. Any changes and modifications made by anyone familiar with this art without departing from the spirit and scope of the present invention shall fall within the protection scope of the present invention. .

100: Infrared reflow temperature detection system 110: Infrared reflow device 111:Light source 112: Bottom plate 120:Semiconductor device 121:Substrate 121a: Active side 122:Chip 122a: Upper surface 122b: Lower surface 123: Connector 130: Temperature sensing unit 140: Ambient temperature sensing unit 150: Reflow temperature calculation unit 160: Thermocouple 170:Power measuring device 180: Optical power meter Ts: temperature sensing signal Te: ambient temperature sensing signal Tr: reflow temperature W:Thickness IR: heating light Pa: actual power Lx: light intensity Tb: lower surface temperature

Figure 1: A block diagram of an infrared reflow temperature detection system according to a first embodiment of the present invention. Figure 2: A schematic diagram of an infrared reflow device reflowing a semiconductor device according to a first embodiment of the present invention. Figure 3: A block diagram of an infrared reflow temperature detection system according to a second embodiment of the present invention.

100: Infrared reflow temperature detection system

110: Infrared reflow device

120:Semiconductor device

130: Temperature sensing unit

140: Ambient temperature sensing unit

150: Reflow temperature calculation unit

160: Thermocouple

IR: heating light

Ts: temperature sensing signal

Te: ambient temperature sensing signal

Tb: lower surface temperature

Tr: reflow temperature

Claims (6)

An infrared reflow temperature detection system, which includes: an infrared reflow device used to reflow a semiconductor device, the semiconductor device has a substrate, a chip and a plurality of connectors, the substrate has an active surface, The chip has an upper surface and a lower surface, and the lower surface faces the active surface. The connectors are located between the substrate and the chip, and the two ends of each connector are respectively connected to the active surface of the substrate and the chip. the lower surface; a temperature sensing unit for sensing the temperature of the upper surface of the chip, and the temperature sensing unit outputs a temperature sensing signal; an ambient temperature sensing unit for sensing the infrared ray The temperature of the environment where the reflow device is located, and the ambient temperature sensing unit outputs an ambient temperature sensing signal; and a reflow temperature calculation unit is electrically connected to the temperature sensing unit and the ambient temperature sensing unit to receive the The temperature sensing signal and the ambient temperature sensing signal are generated, and the reflow temperature calculation unit substitutes the temperature sensing signal and the ambient temperature sensing signal into a reflow temperature calculation equation to calculate a reflow of the lower surface of the chip. Soldering temperature, the reflow temperature calculation equation is that the reflow temperature calculation unit measures the different temperature sensing signals of the upper surface of the chip through the temperature sensing unit, the ambient temperature calculation unit and a thermocouple in advance and The data obtained from the lower surface temperature of the lower surface of the wafer under different ambient temperature sensing signals of the environment in which the infrared reflow device is located are obtained through regression analysis. For example, in the infrared reflow temperature detection system of claim 1, the temperature sensing unit is an infrared thermometer. For example, claim 1 is an infrared reflow temperature detection system, wherein the reflow temperature calculation equation is that the reflow temperature calculation unit measures the infrared reflow through the temperature sensing unit, the reflow temperature calculation unit and a thermocouple in advance. The chip was installed under different heating times and different input powers. The data obtained from the temperature sensing signal of the upper surface, the ambient temperature sensing signal of the environment where the infrared reflow device is located, and the lower surface temperature of the lower surface of the chip are obtained through regression analysis. For example, in the infrared reflow temperature detection system of claim 1 or 3, the reflow temperature calculation equation obtained by the regression analysis of the reflow temperature calculation unit also includes the thickness of the wafer. For example, the infrared reflow temperature detection system of claim 1 or 3 includes a power measurement device used to measure an actual power of the infrared reflow device, and the reflow temperature calculation unit performs regression analysis The obtained reflow temperature calculation equation also includes the actual power of the infrared reflow device. If the infrared reflow temperature detection system of claim 1 or 3 includes an optical power meter, the optical power meter is used to measure the light intensity of a heating light emitted by the infrared reflow device, and the reflow temperature is calculated The reflow temperature calculation equation obtained by unit regression analysis also includes the illumination intensity of the heating light.

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