US20060144278A1

US20060144278A1 - Methods for Testing Single-Use Devices

Info

Publication number: US20060144278A1
Application number: US10/905,176
Authority: US
Inventors: David Gerez
Original assignee: Schlumberger Technology Corp
Current assignee: Schlumberger Technology Corp
Priority date: 2004-12-20
Filing date: 2004-12-20
Publication date: 2006-07-06

Abstract

Methods for testing single-use electrical devices (e.g., explosive detonators and initiators) are provided to ensure operating reliability of such devices when used in the field. These methods facilitate testing of non-destructible components of single-use electrical devices at operating parameters during production or anytime before field use.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to testing of devices, and more particularly to methods for testing single-use electrical devices for oilfield operations.
2. Background of the Invention
Testing of single-use devices during or after production and before field use poses a particular problem. It is difficult to be certain that such a single-use device will function as intended in the field, as any definitive operational test would, by definition, leave the device unusable. For example, electrical components of explosive devices (e.g., detonators, charges, initiators, and other explosive-related single-use devices) are destroyed upon detonation, thus conventional testing techniques are inadequate to fully test such devices at operating parameters.
Presently, one approach for testing single-use devices is to take a limited sample of the completed units under production, and carry out a destructive test of this sample. Standard statistical guidelines may then provide the probability that the remaining devices outside the sample will perform satisfactorily. While providing testing of the sample devices at operational parameters, this approach will not account for unique conditions found in the remaining devices outside the sample, which may cause malfunctioning or inoperability.
Another approach for testing single-use devices is to test the components of a single-use device as thoroughly as possible but short of operational levels which may cause destruction. For example, a capacitor in an electronic circuit of an explosive detonator may be tested by applying a voltage to the device, but not one sufficiently high to trigger the detonator. The capacitor may be charged during operations to 1200-1500V, but only be charged to 1000V in the production test. Thus, a weakened capacitor that would fail at 1100V would not be detected, and may result in a field failure. Therefore, while this type of testing identifies some faults at sub-operational levels, it does not stress the system to the same extent as operational use.
Accordingly, there exists a need for methods to test single-use devices such that the devices are still operational for use in the field.

SUMMARY

The present invention relates to methods for producing and testing single-use electrical devices to ensure operating reliability of such devices when used in the field. These methods facilitate testing of non-destructible components of single-use electrical devices at operating parameters during production.
Some embodiments of the present invention include a method for testing any non-destructive components on an electrical circuit board at operating parameters during production, yet before any actual single-use components are installed. In such embodiments, any single-use components may be installed on the circuit board after the non-destructive components are tested.
Other embodiments of the present invention include a method for testing any non-destructive components on an electrical circuit board at operating parameters during production and after single-use components are installed. In such embodiments, the conductive paths connecting the single-use components to the non-destructive components are left incomplete until after the non-destructive components are tested. Once the non-destructive components are tested at operating parameters, the conductive paths between the single-use components and the non-destructive components are completed.
Other or alternative embodiments of the present invention will be apparent from the following description, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:
FIG. 1 illustrates an electrical schematic view of a prior art EFI initiated detonator, which may be assembled and tested according to various embodiments of the testing method of the present invention.
FIG. 2 illustrates a schematic view of a single-use device being assembled in accordance with an embodiment of the testing method of the present invention, where the single-use component is installed after the non-destructive components are tested.
FIGS. 3-6 illustrate schematic views of a single-use device being assembled in accordance with various embodiments of the testing method of the present invention, where the single-use component is installed before the non-destructive components are tested.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
In the specification and appended claims: the terms “connect “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via another element”; and the term “set” is used to mean “one element” or “more than one element”. As used herein, the terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”; “above” and “below”; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. Moreover, as used herein, the term “single-use” describes a device or component of a device that is designed to only perform a function once under operational parameters before it is rendered inoperable; and the term “non-destructive” describes a device or component that is not a single-use device or component.
A single-use device may include one or more components in electrical connection. For example, with respect to FIG. 1 detonator device 10, as described in U.S. patent Ser. No. 10/711,809 and shown in FIG. 1, may include one or more filters, addressable chips, capacitors, resistors, transformers, switches, and diodes for the purpose of receiving a voltage to activate an electrical initiator. The initiator may be an exploding foil initiator (EFI), an exploding bridge wire (EBW) initiator, a semiconductor bridge (SCB) initiator, hotwire or another electrically activated initiator. While some embodiments of this invention are described for use with testing an initiator component of a detonator, other embodiments may be used with igniters, explosive-actuated devices such as exploding bolts, or propellant-actuated devices such as piston-driven motors, cutters, valves and other similar devices.
Generally, it may be desirable to test a single-use device, like the detonator 10 of FIG. 1, during or after production to ensure operating reliability when used in the field. According to one embodiment of the present invention, as shown in FIG. 2, the single use device 200 may be tested at operating parameters during production, yet before any actual single-use components are installed. Once the non-destructive or multi-use components are tested at operating parameters, the single-use components may be installed.
According to another embodiment of the present invention, as shown in FIGS. 3-6, the single-use device 200 may be tested at operating parameters during production with all single-use components installed, yet with an incomplete conductive path between the single-use components and non-destructive components. Once the non-destructive components are tested at operating parameters, the conductive path between the single-use components and the non-destructive components is completed.
With more particularity, FIG. 2 illustrates a single-use device 200 having a circuit board 210, a single-use component 215 (also known as a “one-shot part”), and one or more non-destructive components 220A, 220B, 220C, 220D. The circuit board 210 may be a conventional printed-circuit-board (PCB), a flexible PCB, the substrate of a multi-chip module (MCM), or other circuit board. In alternative embodiments, the electrical components may be fused together without the use of a circuit board. Typically, non-destructive electronic components 220A, 220B, 220C, and 220D may be assembled onto the PCB 210 by applying a solder paste onto conductive pads on the PCB and then placing the each component onto its respective pad. The solder paste prevents shifting of the components during processing. The PCB 210 is then passed through a reflow oven (or other conventional solder heating source such as a wave-solder machine or a manually-operated soldering iron to melt the solder and establish a mechanical and electrical bond between the pads of the PCB and the components 220A, 220B, 220C, and 220D. While this may be a typical technique for connecting electronic components to a PCB, other conventional techniques (e.g., laser-welding or ultrasonic-welding) may also be applied in achieving the present invention. The process may be repeated for components mounted on the other side of the PCB 210. Finally, the board may be tested in an electrical-test fixture designed to apply electrical stimuli at specified test points and detect the response of the circuit. This may be a “bed-of-nails” fixture designed to establish contact with test points on the board, a fixture that interfaces through the external interfaces of the board (e.g., connecting wires), or other similar fixture.
Still with reference to FIG. 2, in one embodiment of the present invention, a method is provided for performing an electrical test of a single-use device 200, before connection of the single-use component 215 to the PCB 210. In this embodiment, only after completion of the electrical test is the single-use component 215 mounted on the board 210. The single-use component 215 may be mounted using one of several possible techniques. First, the single-use device 215 may be soldered to a conductive pad 212 by applying solder and re-heating the board in the reflow oven. Second, instead of solder, a conductive epoxy may be used to set the component 215 to the pad 212 of the PCB 210 at a relatively low temperature, thus the device 200 would not be subjected to the high temperatures of a reflow oven. In addition, this technique could be applied without modifying the existing board design or introducing the complexity of additional components (as shown in FIGS. 4, 5, and 6). Third, the component 215 may be soldered to the PCB 210 by locally heating the conductive pad 212 (e.g., as with a hot iron, a stream of heated gas, ultrasonic energy, infrared energy, halogen light, and so forth). Other mechanical techniques for connecting the single-use component 215 to the pad 12 of the PCB 210 (e.g., jumpers and latching) may also be employed, however, because many single-use devices (e.g. EFI detonators) require a fast-rising high-current pulse, the resistance and inductance of the circuit are critical parameters and the use of many mechanical connectors may be precluded.
With respect to FIG. 3, another embodiment of the present invention is provided including a method for testing a single-use device 200 by delaying the establishment of a conductive path between the single-use component 215 and the non-destructive components 220A, 220B, 220C, 220D. Under this method, the single-use component 215 is soldered to the pad 226 of the PCB 210 using the standard production process; however, a gap 223 in the conductive path between the pads 225, 226 for the single-use component 215 and the rest of the circuit (i.e., the non-destructive components 220A, 220B, 220C, 220D) provides an electrical isolation such that the circuit is maintained and testing can be carried out without activating the single-use component 215. Once the test is complete, a conductive path may be established in different ways (as shown in FIGS. 4-6).
FIG. 4 illustrates an embodiment of the technique for establishing a conductive path whereby the gap 223 between the single-use component 215 and non-destructive components 220A, 220B, 220C, 220D is bridged by applying solder 230. Alternatively, soldering wires, low-resistance surface-mount resistors, a conductive strip or web, conductive epoxy, or other conductive materials may also be employed to bridge the gap 230. In one embodiment, a wire is used to bridge the gap 223 between the conductive pads 225, 226 instead of the solder bead 223 as shown. The wire may be connected to the conductive pads 225, 226 by applying a bead of solder to each end of the wire, by gluing or applying an epoxy to the wire, or by application of another adhesive material.
FIG. 5 illustrates another embodiment of the technique for establishing a conductive path whereby the gap 223 between the single-use component 215 and non-destructive components 220A, 220B, 220C, 220D is bridged. In this embodiment, the pad 226 for mounting the single-use component 215 and the pad 225 connecting to the non-destructive components 220A, 220B, 220C, 220D are on opposite sides of the PCB 210. The non-conductive gap 223 is maintained by the thickness of the PCB 210, which itself may be fabricated from an insulating material (e.g., polyamide, PFTE, ceramic, or figerglass-reinforced plastic, or other insulating material). The pads 225, 226 and the PCB 210 may be fabricated with a hole therethrough for insertion of a conductive bridging element 240 to connect the component 215 to the non-destructive components 220A, 220B, 220C, 220D after testing is complete. Alternatively, a hole may be drilled through the pads 225, 226 and the PCB 210 after production or after testing, as with a laser or mechanical drill. Once again, after testing is complete, a conductive bridging element may be employed. The bridging element 240 may be formed by any number of means including, but not limited to, solder set by a localized heating process (e.g., a hot iron or stream of hot gas), electrical connections between layers, such as inter-layer vias, one or more pins (e.g., rods, bolts, rivets, or other similar structural connecting element) inserted through the hole in board 210 such that each pad 225, 226 is engaged, a conductive epoxy, and so forth.
FIG. 6 illustrates yet another embodiment of the technique for establishing a conductive path whereby the gap 223 between the single-use component 215 and non-destructive components 220A, 220B, 220C, 220D is bridged by a moveable flap 250. In this embodiment, the flap 250 is mounted on the board 210 with a conductive pad 225 on its surface. The flap 250 may be moved by shifting, rotating, or folding over, to establish a connection with the pad 226 of the single-use component 215. The flap 250 may be held in place by any conventional means including, but not limited to, soldering, conductive epoxy, pins, and so forth.
Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.

Claims

1. A method for testing an electrical device having a single-use component and another component, comprising:

testing the device; and

electrically connecting the single-use component to the other component, wherein the testing is performed before the single-use component and the other component are electrically connected.

2. The method of claim 1, wherein electrically connecting the single-use component and the other component comprises mounting the single-use component to a circuit board having a conductive path formed between the single-use component and the other component.

3. The method of claim 1, further comprising:

mounting the single-use component and the other component to a circuit board before the testing is performed,

wherein electrically connecting the single-use component and the other component comprises completing a conductive path between the single-use component and the other component.

4. A method for producing an electrical device having a single-use component and at least one other component, comprising:

providing a circuit board for receiving the single-use component and the at least one other component and a conductive path for electrically connecting the single-use component and the at least one other component;

installing the at least one other component on the circuit board;

installing the single-use component on the circuit board, wherein the conductive path is incomplete between the single-use component and the at least one other component;

testing the at least one other component; and

completing the conductive path between the single-use component and the at least one other component.

5. The method of claim 4, wherein completing the conductive path between the single-use component and the at least one other component comprises:

applying solder between the between the single-use component and the at least one other component.

6. The method of claim 4, wherein completing the conductive path between the single-use component and the at least one other component comprises:

connecting a wire between the single-use component and the at least one other component.

7. The method of claim 4, wherein completing the conductive path between the single-use component and the at least one other component comprises:

mounting a resistor between the single-use component and the at least one other component.

8. The method of claim 4, wherein completing the conductive path between the single-use component and the at least one other component comprises:

applying a conductive strip between the single-use component and the at least one other component.

9. The method of claim 4, wherein installing the components on the circuit board comprises:

mounting the single-use component on one side of the circuit board; and mounting the at least one other component on the other side of the circuit board.

10. The method of claim 9, wherein completing the conductive path between the single-use component and the at least one other component comprises:

forming a hole in the circuit board between the single-use component and the at least one other component; and

filling the hole with a conductive element.

11. The method of claim 10, wherein the conductive element is solder.

12. The method of claim 10, wherein the conductive element is a pin.

13. The method of claim 4, wherein the electrical device is an explosive detonator.

14. The method of claim 13, wherein the single-use component is selected from a group consisting of an exploding foil initiator, an exploding bridge wire initiator, a semiconductor bridge initiator, and a hotwire.

15. The method of claim 13, wherein the at least one other component is selected from a group consisting of a filter, an addressable chip, a capacitor, a resistor, a transformer, a switch, and a diode.

16. The method of claim 4, wherein the electrical device is an igniter.

17. The method of claim 16, wherein the single-use component is selected from a group consisting of an exploding foil initiator, an exploding bridge wire initiator, a semiconductor bridge initiator, and a hotwire.

18. The method of claim 16, wherein the at least one other component is selected from a group consisting of a filter, an addressable chip, a capacitor, a resistor, a transformer, a switch, and a diode.

19. A method for producing an electrical device having a single-use component and a multi-use component, comprising:

providing a circuit board having a conductive pad for receiving the single-use component, a conductive pad for receiving the multi-use component, and a conductive path for electrically connecting the conductive pad of the single-use component and the conductive pad of the multi-use component;

installing the multi-use component on one of the conductive pads of the circuit board;

installing the single-use component on the other conductive pad of the circuit board, wherein the conductive path is incomplete between the conductive pads;

testing the multi-use component in a test fixture; and

completing the conductive path between the conductive pads.

20. The method of claim 17, wherein completing the conductive path between the conductive pads comprises:

connecting a wire between the conductive pads.