CN114878037A - A miniature overlapping flower strain gauge - Google Patents

Abstract

The invention discloses a miniature overlapping flower strain gauge, comprising a multi-layer substrate; a sensitive grid is arranged on each layer of the substrate, and the included angle between each sensitive grid and the center line of the substrate is different; each sensitive grid is provided with a Two pads, the distance between the two pads of each sensitive gate is equal, and the positions between all the pads are staggered on the surface of the substrate, and the area between the two pads of each sensitive gate is on different substrates There are n pads, and n is equal to the number of sensitive gates minus one. In the case of reducing the size of the substrate, the pad spacing is increased to avoid solder sticking.

Description

A miniature overlapping flower strain gauge

technical field

The invention belongs to the field of foil resistance strain gauges, and relates to a miniature overlapping flower strain gauge.

Background technique

Foil resistance strain gauges have been widely used in the manufacture of various high-precision sensors and stress and strain testing in various environments. With the boom in consumer electronics, the use of circuit boards and integrated chips has increased dramatically. However, stress concentration or damage is very easy to occur during the transportation and installation of circuit boards and integrated chips. Therefore, a strain gauge is required to detect the stress condition of circuit boards or chips to analyze the reliability of circuit boards, so as to optimize circuit board performance. Design and transportation, packaging methods, improve the reliability of the circuit board.

With the development of miniaturization of consumer electronic products, the size of the circuit board or chip used is also very small. To test the stress in a small area on the circuit board or in multiple directions at a certain point, a multi-axis with a particularly small size is required. strain gauge. However, the existing overlapping flower strain gages cannot meet the testing requirements of tiny chips and circuit boards, mainly because the pad spacing of each strain gage is particularly small, and solder adhesion is very likely to occur after lead welding, resulting in abnormal resistance and other problems. And it will lead to the need for a large-sized substrate, usually 2.5mm × 2.5mm and above, in order to avoid the problem of solder adhesion.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art, and to provide a miniature overlapping flower strain gauge, which increases the pad spacing and avoids the phenomenon of solder sticking when the size of the substrate is reduced.

To achieve the above object, the present invention adopts the following technical solutions to realize:

A miniature overlapping flower strain gauge including a multi-layer substrate;

Each layer of substrate is provided with a sensitive grid, and the included angle between each sensitive grid and the center line of the substrate is different; each sensitive grid is provided with two pads, and the distance between the two pads of each sensitive grid is equal , and the positions between all the pads are staggered on the surface of the substrate, and the area between the two pads of each sensitive gate is provided with n pads on different substrates, where n is equal to the number of sensitive gates minus one.

Preferably, adhesive glue is used for bonding between the substrate and the sensitive grid of the next layer.

Further, the adhesive is in the form of a semi-cured film.

Preferably, the dimensions of each substrate are the same.

Preferably, each pad is soldered with a lead.

Further, the lead wire adopts flat enameled wire, the thickness of the flat enameled wire is 0.06-0.08mm, and the width is 0.12-0.16mm.

Preferably, the surface of each pad is provided with a copper plating layer.

Preferably, the pads on each sensitive gate are oriented in the same direction.

Preferably, the surface size of the strain gauge is 1.5mm×1.5mm.

Preferably, the substrate is three layers, and the distance between two pads of each sensitive gate is the sum of the distance between two pad widths and the distance between three adjacent pads in the overlapping space.

Compared with the prior art, the present invention has the following beneficial effects:

In the present invention, by increasing the distance between the two pads of each sensitive gate, the positions between all the pads are staggered on the surface of the substrate, and at the spatial level, other sensitive gates can be arranged between the two pads Therefore, when the overall width of the pad remains unchanged, the distance between two pads of the same sensitive gate is increased to avoid the phenomenon of solder sticking, and the size of the substrate is not limited by the distance between the pads, which can be reduced. Strain gage surface dimensions.

Further, a semi-cured film-like adhesive is used for bonding between the substrate and the sensitive grid, which is both sticky and non-flowing, and no glue overflow occurs after pressing. Spilled glue will contaminate the pads and affect lead soldering.

Further, the size of each layer of the substrate is the same, which can realize the decal of the entire strain gage, the alignment is simple, the decal efficiency is high, and the modification size error is reduced.

Further, the pads are welded with flat enameled wires, which can reduce the overall thickness of the strain gauge.

Description of drawings

Fig. 1 is the front view of the three-layer structure and the lead mode of the miniature overlapping flower strain gauge of the present invention;

Fig. 2 is the top view of the three-layer structure and lead mode of the miniature overlapping flower strain gauge of the present invention;

FIG. 3 is a schematic diagram of a first-layer sensitive gate structure of the present invention;

FIG. 4 is a schematic diagram of the second-layer sensitive gate structure of the present invention;

FIG. 5 is a schematic diagram of a third-layer sensitive gate structure of the present invention.

Among them: 1-substrate; 2-sensitive gate; 3-adhesive; 4-pad; 5-lead.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the The embodiments of the present invention, and all other embodiments obtained by those of ordinary skill in the art without creative work, fall within the protection scope of the present invention.

It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to the directions in the drawings, and the words "inner" and "outer" ” refer to directions towards or away from the geometric center of a particular part, respectively.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in FIG. 1 , it is a miniature overlapping flower strain gauge according to the present invention, comprising a multi-layer substrate 1 .

The size of each layer of substrate 1 is the same, and each layer of substrate 1 is provided with a sensitive grid 2, and the angle between each sensitive grid 2 and the center line of the substrate 1 is different; each sensitive grid 2 is provided with two welding Pad 4, the two pads 4 of each sensitive gate 2 are equally spaced, and the positions between all pads 4 are staggered on the surface of the substrate 1, and the area between the two pads 4 of each sensitive gate 2 There are n pads 4 on different substrates 1 , and n is equal to the number of sensitive gates 2 minus one.

The adhesive 3 is applied on the sensitive grid 2, and then laminated and laminated with the substrate 1. After thermal curing, the substrate 1 of the single-piece strain gauge is formed, and then the lead 5 is welded on the pad 4 of the strain gauge. Form a single piece of resistance strain gage.

This embodiment takes the three-way overlapping flower as an example. The six pads 4 and the leads 5 of the strain gauge are arranged and led out in the same direction. Therefore, six pads of equal width and equal spacing are arranged on the width direction of the strain gauge substrate 1 4. The width is 0.15mm, and the spacing is 0.08mm; the distance between the two pads 4 of each layer of strain gauges is the sum of the distance between the width of 2 pads 4 and the spacing of 3 pads 4.

The first layer of strain gauges includes a substrate 1 , a sensitive grid 2 , a pad 4 and a lead 5 , wherein the pads 4 connected to the sensitive grid 2 of the strain gauge are respectively a pad 4c and a pad 4f.

The size of the substrate 1 of the first layer of strain gauges is 1.5×1.5mm, the direction of the sensitive grid 2 is -45°, the center distance between the pads 4c and 4f is 0.69mm, this size is 2 pads 4 width and 3 The distance and the pitch of each pad 4.

In the design method of a miniature overlapping flower strain gauge involved in the present invention, the second layer of the strain gauge comprises a substrate 1, a sensitive grid 2, a pad 4 and a lead 5, wherein the pads 4 connected to the sensitive grid 2 of the strain gauge are respectively Pad 4a and pad 4d.

The size of the substrate 1 of the second layer of strain gauges is 1.5×1.5mm, the direction of the sensitive grid 2 is 45°, the center distance between the pads 4a and 4d is 0.69mm, and this size is 2 pads 4 width and 3 pads The distance and the pitch of the pads 4.

In the design method of a miniature overlapping flower strain gauge involved in the present invention, the third layer of the strain gauge comprises a substrate 1, a sensitive grid 2, a pad 4 and a lead 5, wherein the pads 4 connected to the sensitive grid 2 of the strain gauge are respectively Pad 4b and pad 4e.

The size of the substrate 1 of the third layer strain gauge is 1.5mm×1.5mm, the direction of the sensitive grid 2 is 0°, the center distance between the pads 4b and 4e is 0.69mm, and this size is 2 pads 4 width and 3 The distance and the pitch of each pad 4.

Each pad 4 is soldered with a lead 5, and the lead 5 is a flat enameled wire, the thickness of the flat enameled wire is 0.06-0.08mm, the width is 0.12-0.16mm, and can withstand an ambient temperature of 150°C. The flat enameled wire and the strain gauge pad 4 are fixed by solder points, and the soldering reliability is good.

The size of each layer of the substrate 1 of the three-layer overlapping structure is the same; the six pads 4 and leads 5 of the strain gauge are arranged and led out in the same direction, and the width of the pads 4 is the same, and the distance between the adjacent pads 4 is the same; the three sensitive The included angles of the grid 2 are distributed at -45°, 0° and 45°, and the total thickness of the strain gauge is 0.3 to 0.5 mm.

The manufacturing method of the miniature overlapping flower strain gauge of the present embodiment includes:

The miniature overlapping flower strain gauge is composed of three layers of separate strain gauges. At the same time, the center of the second layer of strain gage sensitive grid 2 and the center of the third layer of strain gage sensitive grid 2 are overlapped and fixed; secondly, a layer of adhesive 3 is applied to the back of the substrate 1 of the first layer of strain gage , after the semi-cured film is formed, it is bonded to the front side of the second layer of strain gauges, and at the same time, the center of the first layer of strain gauge sensitive grid 2 and the center of the second layer of strain gauge sensitive grid 2 are overlapped and fixed; 2 angular direction, -45°, 0° and 45° are pasted in sequence, and after pressing and heat curing, a whole three-layer micro-overlap flower strain gauge is formed.

The upper and lower layers are bonded together by a thin layer of adhesive 3 between each layer of the three-layer strain gauge to form a three-layer overlapping flower strain gauge.

Use a semi-cured film-like adhesive 3. Such as epoxy resin or modified phenolic resin. The manufacturing method is to coat a layer of adhesive liquid of adhesive 3 on the back of the strain gauge substrate 1, and then thermally solidify it at a certain temperature and time to form a semi-cured film with certain adhesiveness.

The size of each layer of the substrate 1 is equal, and the overlapping alignment process with high alignment marking accuracy can accurately determine the center position of the sensitive gate 2, and the alignment is accurate and reliable.

The sensitive grid 2 is made of Evan alloy, and the surface of the pad 4 is subjected to copper plating treatment to improve the reliability of the welding of the lead 5 .

To sum up, the design and manufacturing method of a miniature overlapping flower strain gauge involved in the present invention is creative, and is not limited to the three-way overlapping flower of 1.5mm×1.5mm in the embodiment, but can be extended to larger or smaller overlaps The included angle of the flower strain gauge and the measuring grid is not limited to -45°, 0° and 45°, and can also be used for 0°, 90° or 0°, 45° two-way overlapping flowers, as well as 0°, 60°, 120° and other types of overlapping flower strain gauges.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus.

It should be understood that the above description is for purposes of illustration and not limitation. From reading the above description, many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated herein by reference for the purpose of being comprehensive. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to disclaim such subject matter, nor should it be construed that the applicant has not considered such subject matter to be part of the disclosed subject matter.

Claims (10)

1. a miniature overlapping flower strain gauge, is characterized in that, comprises multilayer base (1); Each layer of the substrate (1) is provided with a sensitive grid (2), and the included angle between each sensitive grid (2) and the center line of the substrate (1) is different; each sensitive grid (2) is provided with two the pads (4), the two pads (4) of each sensitive gate (2) are equally spaced, and the positions between all the pads (4) are staggered on the surface of the substrate (1), each sensitive gate In the area between the two pads (4) of (2), n pads (4) are arranged on different substrates (1), and n is equal to the number of the sensitive gates (2) minus one. 2 . The miniature overlapping flower strain gauge according to claim 1 , wherein the substrate ( 1 ) and the sensitive grid ( 2 ) of the next layer are bonded by adhesive glue ( 3 ). 3 . 3 . The miniature overlapping flower strain gauge according to claim 2 , wherein the adhesive ( 3 ) is in the form of a semi-cured film. 4 . 4. The miniature overlapping flower strain gauge according to claim 1, characterized in that, the dimensions of each layer of substrates (1) are the same. 5. The miniature overlapping flower strain gauge according to claim 1, characterized in that, each pad (4) is welded with a lead (5). 6 . The miniature overlapping flower strain gauge according to claim 5 , wherein the lead wire ( 5 ) adopts flat enameled wire, the thickness of the flat enameled wire is 0.06-0.08mm, and the width is 0.12-0.16mm. 7 . 7. The miniature overlapping flower strain gauge according to claim 1, characterized in that, the surface of each pad (4) is provided with a copper plating layer. 8. The miniature overlapping flower strain gauge according to claim 1, characterized in that the orientation of the pads (4) on each sensitive grid (2) is the same. 9 . The miniature overlapping flower strain gauge according to claim 1 , wherein the surface size of the strain gauge is 1.5 mm×1.5 mm. 10 . 10. The miniature overlapping flower strain gauge according to claim 1, wherein the substrate (1) is three layers, and the spacing between the two pads (4) of each sensitive grid (2) is two pads (4). ) width and the sum of the distances between the three adjacent pads (4) in the overlapping space.

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