JPH0738255A - Connection method of thick film substrate with terminal - Google Patents

Abstract

PURPOSE:To realize a firm solder bond structure for connecting a flanged terminal to a thick-film substrate of rigid structure. CONSTITUTION:A flanged terminal 4 together with a washer 5, is soldered to a thick-film substrate 1. Firstly, the terminal 4 of 52 alloy, for example, is inserted through a hole from the rear to front side of substrate, and a metal washer 5 is inserted into a tip of the terminal 4. The metal washer 5 is ion, etc., with thermal expansion coefficient similar to that of the terminal 4, on the surface of metal wash 5, tinning or solder-plating, etc., is done in advance. When soldering, a solder enters the gap between the metal washer 5 and a thick film conductor 2 pattern by capillarity, and at the same time, an enough amount of solder fillet 6 is formed around the center of terminal 4, on the metal washer 5. Further, a solder also runs over a flange 4a of the terminal, for a solder fillet to be formed, so that, with both upper and lower fillets, more rigid structure is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of soldering a terminal of an electronic component, and more particularly to a method of soldering a terminal through a thick film substrate.

[0002]

2. Description of the Related Art Conventionally, various measures have been proposed in order to prevent cracks due to metal fatigue of solder when a terminal of an electronic component is soldered and fixed to a substrate. FIG. 3 shows an example thereof. As shown in FIG. 3B, the lead from the sensor element is fixed to the substrate 31 in the sensor at the terminal fixing portion A at the tip thereof. That is, as shown in FIG. 3A, the flanged terminal 34 is penetrated through the substrate 31 and soldered. As another example of another structure, as shown in FIG. 4, a metal washer-shaped plate 45 is press-fitted and fixed to a terminal 41 such as a connector penetrating the board 43 and soldered in a state of being floated from the board. is there. Further, there is also a structure in which a metal washer is simply used for soldering.

[0003]

However, in the case of the structure of the flanged terminal 34, in the thermal cycle test for evaluating the metal fatigue and the like, cracks 37 are formed after about 1000 cycles and finally, There is a problem of causing a solder open. Moreover, when the plate 45 is inserted and fixed, it is difficult to manufacture because it requires machining of parts with high dimensional accuracy according to the terminal.
There is also a problem that it takes a lot of time to press-fit in a high-density terminal. Further, even if a metal washer is used, no particular reference is made to the material and the like, and a favorable result cannot be obtained in the thermal cycle test.

[0004]

In order to solve the above problems, the structure of the present invention is such that a terminal of an electronic component is made to penetrate through a component mounting hole provided in a thick film conductor pattern printed on a thick film substrate. In the connection method of soldering together with a metal washer, the metal washer is a material having an intermediate value between the thermal expansion coefficient of the thick film substrate and the thermal expansion coefficient of the solder material used for the soldering, and the heat of the terminal. Composed of a material having a value close to the value of the expansion coefficient, the diameter of the metal washer is smaller than the diameter of the land of the thick film substrate to be soldered, and the metal washer is attached to the penetrating terminal, Performing a soldering step to position the metal washer between the solder and the substrate.

The structure of the related invention is characterized in that the terminal is provided with a locking collar (collar) for locking the terminal on the thick film substrate opposite to the side soldered to the thick film substrate. And

[0006]

The function and effect of the present invention are limited to the materials of the metal washers used for soldering that are suitable for the solder and the substrate, so that the guarantee of durability is improved and the life of the product is extended.

[0007]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a schematic cross-sectional view of a thick film substrate 1 (alumina substrate or the like) to which a terminal 4 (with a locking collar in this example) is soldered according to an embodiment of the present invention. On both surfaces or one surface of the thick film substrate 1, a pattern of a thick film conductor 2 for forming an electric circuit (not shown) and a pattern of a thick film protective glass body 3 are fired by a thick film printing method. A terminal mounting hole is provided in the center. A conductor has a so-called through-hole 8 structure in this mounting hole, and the conductor is fired on the front surface, back surface, and side surface of this mounting hole.

Thereafter, in a solder dipping process, solder is deposited on the conductor pattern 2 which is not covered with the protective glass body 3 pattern of the thick film substrate. Next, the terminal 4 is inserted from the hole on the back surface of the thick film substrate to the front surface. Terminal 4 is 52, for example
It is made of an alloy and has a collar 4a so as not to fall when the thick film substrate 1 is set. Further metal washers 5
Is inserted from the tip of the terminal 4 and is set up to the surface of the thick film substrate 1 (in order to set, the tip of the terminal 4 needs to be arranged so as to face at least above horizontal). The metal washer 5 is made of, for example, iron, is between the thick film substrate 1 and the solder 6, and has a thermal expansion coefficient (hereinafter referred to as α) close to that of the terminal 4. The surface of the metal washer 5 is preliminarily plated with tin or solder to facilitate soldering.

Then, soldering is performed with a soldering iron or the like. At this time, the solder 6 intrudes into the gap between the metal washer 5 and the thick film conductor 2 pattern by capillary action, and a sufficient amount of the solder 6 fillet is formed on the metal washer 5 with the terminal 4 as the center. Also, the collar 4a of the terminal
Solder also wraps around to form a solder fillet, and the upper and lower solder fillets form a stronger structure.

FIG. 2 is a sectional view of an example in which the structure of FIG. 1 is applied to the inside of a pressure sensor mounted on an engine for a bus or truck. Stainless steel (eg SUS316L,
A metal diaphragm 9 made of ASL350) is sandwiched between a ring weld 10 made of stainless steel (for example, SUS316L) having a hole for introducing pressure and a housing 11 made of iron, and its outer periphery is laser-welded. The plate 12 made of an insulating material (for example, ceramic) is used for the housing 1
1 is glued and fixed. The sensor chip 13 made of silicon is anodically bonded to the glass pedestal 14, and the pedestal 14 is adhesively fixed to the housing 11. The terminal 4 (made of 52 alloy, for example) is sealed to the housing 11 by the glass 15. The end faces of the sensor chip 13 and the terminal 4 are wire-bonded with an aluminum wire 16. The silicone oil 17 is poured into the housing 11 and sealed by the expander 18. The terminal 4 and the thick film substrate 1 are soldered via the metal washer 5 shown in FIG.
On the back surface of the thick film substrate 1, a monolithic IC (not shown),
A circuit including a chip capacitor and a thick film conductor 2 is mounted, a thick film resistor (not shown) is printed on the front surface, and conduction on the front and back surfaces is achieved by a through hole structure. The leads 19 are reflow soldered to the thick film substrate 1. The feedthrough capacitor 21 is soldered to the metal case 20 (made of iron, for example), and the lead 19 is inserted into the hole and soldered. Pin 2 of pin assembly 24 including pin 22 (for example, brass) and insulator 23 (for example, fluororubber)
The lead 19 is soldered to the wire 2. Pin assembly 24
Pin 22 of is also the terminal of the connector,
After setting the O-ring 25 and the resin case 26, the housing 11 crimps the entire circumference.

In FIG. 2, when an external pressure is applied to the metal diaphragm 9, the pressure is transmitted to the sensor chip 13 via the silicone oil 17. A diffusion resistance (not shown) is formed on the sensor chip 13 by an IC process, and the pressure is converted into an electric signal by the piezoresistive effect. The converted electric signal is amplified by the thick film substrate 1 through the aluminum wire 16 and the terminal 4, and a connector is formed from the pin 22 of the pin assembly and the resin case 26 through the lead 19 and is output as a voltage signal to the outside. Is output.
The feedthrough capacitor 21 is provided to improve resistance to electromagnetic waves from the outside.

FIGS. 3 (a) and 3 (b) show a conventional pressure sensor in which the metal washer 5 in FIG. 2 is not inserted.
It is known that the number of cycles to reach 0% is about 600 cycles. As shown in FIG. 5, the crack rate means that the angular range θ ° in which cracks are generated in the cooling / heating cycle on the circumference of the solder fillet viewed from directly above is 360% of the whole circumference.
Or not. Here, as shown in Figure 1 (or Figure 2),
If the metal washer 5 is inserted during soldering, the number of cycles until the crack rate reaches 50% is 5
In the case of 2 alloy (α = 10.1PPM / ° C), an iron washer (α = 11.7PPM / ° C) is used and the terminal 4 is brass (α =
At 19 PPM / ° C, when a phosphor bronze (α = 17 PPM / ° C) washer was used, the elongation was extended to 2000 to 2400 cycles (a little over 3 times). Although this depends on the material of the metal washer used, it can be seen that the durability of soldering is significantly improved. In other words, this means that products that could only be guaranteed for one year in the past, for example, can now be guaranteed for three years, which is extremely effective.

Further, the outer diameter of the metal washer 5 is set to the thick film conductor 2
2.5 and φ for the land diameter of (for example, φ3)
The number of cooling / heating cycles when 2.8 is φ2.5 is 20
It is understood that the durability is improved with a washer having a diameter smaller than that of the land diameter of the thick film conductor 2 in the case of 00 cycles and 1500 cycles at φ2.8.

In the above example, the case where the collar 4a is attached to the terminal 4 has been shown, but it goes without saying that the same effect can be obtained without the collar 4a. The metal washer has the same effect even if it has a C-shape with a slit like a spring washer. Although the pressure sensor is shown as an example, any product can be applied as long as it has a structure in which the terminal terminal is passed through the hole of the thick film substrate and soldering is performed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a terminal (with a locking collar) is soldered to a thick film substrate with a metal washer in one embodiment of the present invention.

FIG. 2 is a structural cross-sectional view when the present invention is applied to the inside of a pressure sensor mounted on an engine for a bus / truck or the like.

FIG. 3 is a structural sectional view of a conventional pressure sensor in which a metal washer is not inserted.

FIG. 4 is a structural cross-sectional view of a conventional product in which a metal washer-shaped plate is press-fitted and fixed to a terminal such as a connector penetrating the board, and soldered in a state of floating from the board.

FIG. 5 is a sketch drawing showing a circumferential shape of a solder fillet as viewed from directly above.

[Explanation of symbols]

 1, 31 Thick film substrate 2, 32 Thick film conductor 3, 33 Thick film protective glass body 4, 34 Terminal 4a, 34a Stopper 5 Metal washer 6, 36 Solder fillet 7, 37 Crack 8, 38 Through hole 9 Metal diaphragm 11 Housing 13 Sensor chip 14 Glass pedestal 15 Glass 19 Lead 20 Metal case 21 Feedthrough capacitor 23 Insulator 24 Pin assembly 25 O-ring 26 Resin case 40 Terminal assembly 41 Terminal terminal 42 Housing 43 Printed circuit board 44 Wiring pattern land 45 Plate 47, 48 Solder fillet

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H01R 9/09 B 6901-5E

Claims (2)

[Claims] 1. A connection method in which a terminal of an electronic component is passed through a component mounting hole provided in a thick film conductor pattern printed on a thick film substrate and soldered together with the metal washer, wherein A material having an intermediate value between the coefficient of thermal expansion of the film substrate and the coefficient of thermal expansion of the solder material used for soldering, and a material having a value close to the value of the coefficient of thermal expansion of the terminal, the metal washer The diameter is made smaller than the diameter of the land of the thick film substrate to be soldered, the metal washer is attached to the penetrating terminal, and then a soldering step is performed to separate the metal washer from the solder and the substrate. A method for connecting a thick film substrate and a terminal, characterized in that it is located between them. 2. The terminal is provided with a stop collar (collar) for locking the terminal on the thick film substrate opposite to the side soldered to the thick film substrate. 1. The method for connecting the thick film substrate according to 1 to a terminal.