Test strip for monitoring back drilling depth

Abstract

The utility model discloses a test strip for monitoring back drilling depth, and particularly relates to the technical field of back drilling hole detection, the test strip comprises a test strip body, four corners of the test strip body are sequentially provided with a first test hole, a second test hole, a third test hole and a fourth test hole which penetrate through the test strip body; the test strip body sequentially comprises an A1 layer, an A2 layer, an A3 layer, an A4 layer and an A5 layer from top to bottom; the second test hole in the A2 layer is connected with the fourth test hole in the A2 layer through a wire circuit, and the wire circuit is sequentially connected with the four via holes in the A2 layer. The first test hole in the A3 layer is connected with the third test hole in the A3 layer through a wire circuit, and the wire circuit is sequentially connected with the four via holes from the A3 layer and the A4 layer. According to the utility model, the tedious process of repeated slice inspection is solved, the determination can be carried out by using a universal meter on site, and the production efficiency is improved.

Description

Technical Field

[0001] This utility model relates to the field of back-drilling detection technology, specifically to a test strip for monitoring back-drilling depth. Background Technology

[0002] With the emergence of PCB designs with transmission rates of 10G, 25G, and even higher, signal attenuation on PCBs has become an unavoidable factor. Back-drilling on vias has become a common design practice in the industry, and the stub depth control range after back-drilling is getting smaller and smaller, from less than 0.305mm to less than 0.254mm, then to less than 0.2032mm, and will be even smaller in the future. These increasingly stringent stub requirements place increasingly stringent demands on the back-drilling depth control in PCB production. Since the thickness difference between laminated layers in high-layer boards can typically reach 0.1524mm or even 0.254mm, this thickness variation severely impacts stub control. Therefore, different board thicknesses require different back-drilling depths. To ensure that PCBs of different thicknesses meet stub requirements after back-drilling, it is necessary to determine whether the back-drilling depth is acceptable.

[0003] Currently, the back-drilling depth is designed by calculating the theoretical thickness from the non-drillable layer to the back-drilling layer. After drilling one unit based on the theoretical depth, a section is cut to check if the stub after back-drilling is within the tolerance value. If there is a deviation, the back-drilling depth is adjusted according to the deviation value, and another unit is drilled until the test is qualified. However, this testing method requires multiple grinding of sections and sending them to a physics laboratory for measurement, which is obviously cumbersome and wastes manpower and time. Utility Model Content

[0004] The purpose of this invention is to provide a test strip for monitoring back drill depth, in order to address the aforementioned shortcomings in the technology.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a test strip for monitoring back drill depth, comprising:

[0006] The test strip body has a first test hole, a second test hole, a third test hole and a fourth test hole that penetrate the test strip body in sequence at its four corners, and a first through hole, a second through hole, a third through hole and a fourth through hole that penetrate the test strip body in sequence at its middle part.

[0007] The test strip body comprises, from top to bottom, layers A1, A2, A3, A4, and A5.

[0008] The second test hole on layer A2 is connected to the fourth test hole on it by a wire, and the wire is connected to the four vias on layer A2 in sequence.

[0009] The first test hole on the A3 layer is connected with the third test hole thereon through a wire circuit, and the wire circuit connects the four through holes in turn from the A3 layer and the A4 layer.

[0010] Preferably, the first test hole on the A3 layer is connected with the first through hole thereon through a wire, the second through hole on the A3 layer is connected with the third through hole thereon through a wire, and the fourth through hole on the A3 layer is connected with the third test hole thereon through a wire.

[0011] The first through hole on the A4 layer is connected with the second through hole thereon through a wire, and the third through hole on the A4 layer is connected with the fourth through hole thereon through a wire.

[0012] Preferably, the first test hole, the second test hole, the third test hole and the fourth test hole have a hole diameter of 0.25 mm, are all copper-plated holes, and have a solder ring thickness of 0.1524 mm.

[0013] Preferably, the first through hole, the second through hole, the third through hole and the fourth through hole have a hole diameter of 0.25 mm, are all copper-plated holes, and have a solder ring thickness of 0.1524 mm.

[0014] Preferably, the wire of the wire circuit has a wire width of 0.127 mm.

[0015] Preferably, the A2 layer is set as a must-drill layer, and the A3 layer is set as a must-not-drill layer.

[0016] In the above technical solution, the technical effects and advantages of the present application are provided.

[0017] 1. The cumbersome process of repeated section inspection is solved, and the production efficiency is improved by only measuring on site with a multimeter.

[0018] 2. The production process and material cost are not increased. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.

[0020] Fig. 1 It is an explosion schematic diagram of the present application.

[0021] Fig. 2 It is a whole schematic diagram of the present application.

[0022] BRIEF DESCRIPTION OF DRAWINGS

[0023] 1, test strip body; 2, first test hole; 3, second test hole; 4, third test hole; 5, fourth test hole; 6, first via hole; 7, second via hole; 8, third via hole; 9, fourth via hole; 10, A1 layer; 11, A2 layer; 12, A3 layer; 13, A4 layer; 14, A5 layer. DETAILED DESCRIPTION

[0024] In order for those skilled in the art to better understand the technical scheme of the utility model, the utility model will be further described in detail below in combination with the drawings.

[0025] The utility model provides a kind of test strip for monitoring back drilling depth as shown in Figs. 1-2 The utility model provides a kind of test strip for monitoring back drilling depth as shown in

[0026] The four corners of test strip body 1 are sequentially provided with first test hole 2, second test hole 3, third test hole 4 and fourth test hole 5 penetrating test strip body 1;

[0027] The aperture of first test hole 2, second test hole 3, third test hole 4 and fourth test hole 5 is 0.25mm, and first test hole 2, second test hole 3, third test hole 4 and fourth test hole 5 are all copper immersion holes, and the thickness of welding ring thereon is 0.1524mm;

[0028] The middle part of test strip body 1 is sequentially provided with first via hole 6, second via hole 7, third via hole 8 and fourth via hole 9 penetrating test strip body 1;

[0029] The aperture of first via hole 6, second via hole 7, third via hole 8 and fourth via hole 9 is 0.25mm, and first via hole 6, second via hole 7, third via hole 8 and fourth via hole 9 are all copper immersion holes, and the thickness of welding ring thereon is 0.1524mm;

[0030] Test strip body 1 sequentially includes A1 layer 10, A2 layer 11, A3 layer 12, A4 layer 13 and A5 layer 14 from top to bottom;

[0031] Second test hole 3 on A2 layer 11 and fourth test hole 5 thereon are connected by wire circuit, and the wire circuit sequentially connects four via holes of A2 layer 11, and the wire width of wire circuit is 0.127mm;

[0032] First test hole 2 on A3 layer 12 and third test hole 4 thereon are connected by wire circuit, and the wire circuit sequentially connects four via holes from A3 layer 12 and A4 layer 13, and the wire width of wire circuit is 0.127mm.

[0033] The first test hole 2 on the A3 layer 12 is connected with the first via hole 6 thereon through a wire, the second via hole 7 on the A3 layer 12 is connected with the third via hole 8 thereon through a wire, and the fourth via hole 9 on the A3 layer 12 is connected with the third test hole 4 thereon through a wire;

[0034] The first via hole 6 on the A4 layer 13 is connected with the second via hole 7 thereon through a wire, and the third via hole 8 on the A4 layer 13 is connected with the fourth via hole 9 thereon through a wire.

[0035] The back drilling is from the A1 layer 10 downwards, the A2 layer 11 is set as a must-drill layer, the A3 layer 12 is set as a must-not-drill layer, the A4 layer 13 is an adjacent layer, and the A5 layer 14 is another layer;

[0036] After back drilling, the open and short circuit conditions between the test holes are measured by using a multimeter;

[0037] In the case that the back drilling drills through the A2 layer 11 and does not drill to the A3 layer 12, the first test hole 2 and the third test hole 4 are measured, the first test hole 2 and the third test hole 4 are in conduction, the second test hole 3 and the fourth test hole 5 are measured, the second test hole 3 and the fourth test hole 5 are in conduction, the first test hole 2 and the second test hole 3 are measured, the first test hole 2 and the second test hole 3 are disconnected, the third test hole 4 and the fourth test hole 5 are measured, and the third test hole 4 and the fourth test hole 5 are disconnected;

[0038] If the A2 layer 11 is not drilled through, the first test hole 2, the second test hole 3, the third test hole 4 and the fourth test hole 5 are in conduction, and it is judged as unqualified;

[0039] If the A3 layer 12 is drilled through, the first test hole 2, the second test hole 3, the third test hole 4 and the fourth test hole 5 are disconnected, and it is judged as unqualified;

[0040] The test strip is placed near the empty position of the unit plate, and is as close as possible to the via hole to be back drilled, when back drilling, the test strip is drilled first, and then a multimeter is used to detect whether the back drilling is qualified, if not, the back drilling depth is adjusted according to the measurement result, another test strip is drilled, and the measurement is qualified.

[0041] The utility model discloses simple and convenient operation, and solves the tedious procedure of repeated slice inspection, and only needs to measure on site by using a multimeter, improves production efficiency, and does not increase production process and material cost.

[0042] The above has only described certain exemplary embodiments of the present application by way of illustration, and it is needless to say that the described embodiments can be modified in various ways without departing from the spirit and scope of the present application for those skilled in the art. Therefore, the above drawings and descriptions are illustrative in nature, and should not be understood as limiting the scope of protection of the claims of the present application.

Claims

1. A test strip for monitoring back drill depth, characterized in that, include: The test strip body (1) has a first test hole (2), a second test hole (3), a third test hole (4) and a fourth test hole (5) that pass through the test strip body (1) in sequence at its four corners, and a first through hole (6), a second through hole (7), a third through hole (8) and a fourth through hole (9) that pass through the test strip body (1) in sequence at its middle part. The test strip body (1) includes, from top to bottom, layers A1 (10), A2 (11), A3 (12), A4 (13) and A5 (14). The second test hole (3) on the A2 layer (11) is connected to the fourth test hole (5) on it by a wire line, and the wire line is connected to the four vias of the A2 layer (11) in sequence; The first test hole (2) on the A3 layer (12) is connected to the third test hole (4) on it by a wire line, and the wire line connects four vias from the A3 layer (12) and the A4 layer (13) in sequence.

2. The test strip for monitoring back drill depth according to claim 1, characterized in that: The first test hole (2) on the A3 layer (12) is connected to the first via (6) thereon by a wire, the second via (7) on the A3 layer (12) is connected to the third via (8) thereon by a wire, and the fourth via (9) on the A3 layer (12) is connected to the third test hole (4) thereon by a wire. The first via (6) on the A4 layer (13) is connected to the second via (7) thereon by a wire, and the third via (8) on the A4 layer (13) is connected to the fourth via (9) thereon by a wire.

3. The test strip for monitoring back drill depth according to claim 1, characterized in that: The diameter of the first test hole (2), the second test hole (3), the third test hole (4) and the fourth test hole (5) is 0.25mm. The first test hole (2), the second test hole (3), the third test hole (4) and the fourth test hole (5) are all copper-plated holes, and the thickness of the solder ring on them is 6mil.

4. The test strip for monitoring back drill depth according to claim 1, characterized in that: The diameter of the first via (6), the second via (7), the third via (8) and the fourth via (9) is 0.25 mm. The first via (6), the second via (7), the third via (8) and the fourth via (9) are all copper-plated vias, and the thickness of the solder ring on them is 0.1524 mm.

5. A test strip for monitoring back drill depth according to claim 1, characterized in that: The conductor width of the conductor line is 0.127 mm.

6. A test strip for monitoring back drill depth according to claim 1, characterized in that: The A2 layer (11) is set as a layer that must be drilled through, and the A3 layer (12) is set as a layer that must not be drilled through.

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