Abstract:
An adapter is disclosed that allows simplified connection of thermocouples to a data logger. In one embodiment, multiple thermocouple connectors are positioned within the adapter. The adapter then attaches to a data logger with a simple male/female connection scheme so that the multiple thermocouple connectors are simultaneously coupled to the data logger. The thermocouple connectors are already organized within the adapter so that each thermocouple is plugged into its proper location on the data logger.

Description:
FIELD 
       [0001]    The present disclosure relates to methods and adapters for mechanically and electrically connecting thermocouples to data loggers. 
       BACKGROUND 
       [0002]    Conveyor ovens (also called furnaces) are used in a variety of industries including the electronics, baking, and painting industries. Generally, conveyor ovens have multiple heating zones and may have one or more cooling zones through which product is conveyed. The heating zones are thermally isolated from each other by air curtains or other means. Such thermal isolation allows each zone to be maintained at a temperature that differs from other zones in the oven. A particular advantage of conveyor ovens with multiple heating zones is that products can be heated to different temperatures at different times and rates as they pass through the oven. 
         [0003]    In the electronics industry, conveyor ovens, known as reflow ovens, are used to electrically bond electronic components to printed circuit boards (PCBs) with solder paste. Typically, the soldering process within a conveyor oven can be characterized by the following phases: preheat or ramp phase, the dwell or soak phase, the reflow or spike phase and the cooling phase. In the preheat phase, the solder paste is heated from room temperature to a preheat temperature to promote evaporation of the solvents, or carriers, in the solder paste. During the soak phase, the solder paste is permitted to “soak” for a predetermined period of time at a temperature range at which the flux, the active ingredient in the solder paste, becomes active. In the reflow phase, the solder paste is heated above the liquidous, or melting temperature of the solder for a predetermined period of time sufficient to permit reflow (i.e., melting or wetting) of the solder paste. In the cooling phase, the solder joint solidifies, thereby electrically bonding the components to the circuit board. 
         [0004]    Typically, the thermal requirements for a solder paste (also called solder paste specifications) for preheat, soak and reflow phases are specified by the manufacturer of the paste. Generally speaking, “profiling” is the process of determining the process settings for the oven that will best satisfy the thermal requirements of the solder paste without damaging the electronic components. Such process settings may include, for example, the temperature settings of each oven zone and the oven conveyor speed. 
         [0005]    Devices for measuring the temperature profile of a product conveyed through an oven (i.e., the temperature response of the product) are known. For example, electronic data loggers (also called data collectors or monitors) have been developed that attach thermocouple sensors to a test PCB. One such data logger, the M.O.L.E.® temperature profiler, is an oven profiler sold commercially by Electronic Controls Design, Inc., of Milwaukie, Oreg. Beyond the M.O.L.E.®, the test PCB has various thermocouples strategically placed thereon. Traditionally, each thermocouple is connected directly to the electronic data logger. The electronic data logger is physically spaced apart from the PCB so as not to affect the heating of the PCB and thereby cause inaccurate temperature profiling. The data logger stores temperature information measured by the thermocouples and that information can be processed to determine and control the optimal temperature profile of the product. 
         [0006]    Once the data logger has passed through the oven, the collected data is downloaded to a computer using a special docking station, or via RF or cable. A software package located on the computer graphically illustrates a temperature profile of the collected data and provides a comparison to an optimal profile. The operator estimates changes to the oven settings for reducing the difference between the temperature response of the assembly and the desired thermal profile to within an allowable tolerance. The operator adjusts the oven settings and repeats the process until the appropriate thermal requirements for the solder paste are reached. 
         [0007]    If several thermocouples are used, however, the thermocouples can quickly become tangled and difficult to organize. Additionally, it is difficult to coordinate into which data logger slots the thermocouples should be plugged. Even further, there is increasing commercial pressure to process smaller parts that require more temperature sensors to obtain a proper temperature profile. Ovens are also decreasing in size, forcing data loggers to become smaller. With the decrease in data logger size and the increase in inputs to the data loggers, the connection schemes for commercially available thermocouple connectors are not sustainable. 
         [0008]    It is desirable to increase the number of thermocouples that can be attached to a data logger in an efficient and user-friendly manner. The present disclosure is aimed at resolving this and related problems in the art. 
       SUMMARY 
       [0009]    A first embodiment of the present disclosure describes an adapter for a data logger comprising a housing and at least two removable thermocouple connectors positioned within the housing. The housing allows easy organization of the thermocouples and allows multiple thermocouples to be simultaneously plugged into the data logger with a single male/female-type snap fit. 
         [0010]    A second embodiment of the present disclosure describes a method of thermal profiling comprising grouping multiple thermocouples together. Each thermocouple comprises a thermocouple junction electrically connected to a first lead and a second lead. The first lead and the second lead of each thermocouple are connected to a thermocouple connector. The multiple thermocouple connectors are coupled inside of a single housing, the housing is connected to a data logger, and temperature data from the multiple thermocouples is collected via the thermocouple connectors. 
         [0011]    The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  illustrates a circuit board and a data logger being transported along a conveyor belt inside an oven with multiple temperature zones according to the present disclosure. 
           [0013]      FIG. 2  illustrates multiple thermocouples attached on one end to different areas of a circuit board and attached on the other end to a data logger according to the present disclosure. 
           [0014]      FIG. 3  illustrates a data logger with multiple thermocouple adapters attached thereto. 
           [0015]      FIG. 4  illustrates a top view of an adapter according to the present disclosure. 
           [0016]      FIG. 5  illustrates a detailed view of the adapter with multiple thermocouples arranged therein. 
           [0017]      FIG. 6  illustrates an exploded view of a thermocouple adapter according to the present disclosure. 
           [0018]      FIG. 7  is a flowchart illustrating a method of using a data logger, thermocouples, and thermocouple adapters. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  shows a conveyor belt  10  of an oven with multiple temperature zones Z 1 -Z 7 . A circuit board  12  is shown on top of the conveyor belt  10 . The circuit board  12  is attached to a data logger  14  by a series of wires  16 , some of which may include thermocouples as will be explained in more detail below. The data logger  14  collects temperature data of various points on the circuit board  12  by using thermocouple junctions (not shown) attached to the circuit board. The temperature data is transmitted to the data logger via the series of wires  16 . After the data logger  14  collects the temperature data, it passes the data to a computer  18  which is operable to analyze the data and display corresponding oven profile information to a user. It will be recognized that the present embodiments are not limited to conveyor ovens or the use of circuit boards. The embodiments described herein can be used to measure any temperature data collected from thermocouples independent of the operating environment. 
         [0020]      FIG. 2  shows the connection of the data logger  14  to the circuit board  12  in more detail. The circuit board  12  of this embodiment is positioned on a conveyor belt  10  and includes two elements  20   a,    20   b.  The elements  20   a,    20   b  could be one of a transistor, a resistor, a capacitor, a microchip, or any other element that would be known in the art. Two elements are shown only for simplicity, as a circuit board typically includes numerous elements. A first thermocouple junction  22  is attached near the first element  20   a.  A second thermocouple junction  24  is positioned between the circuit board  12  and the first element  20   a.  A third thermocouple junction  26  and a fourth thermocouple junction  28  are affixed to various other sections of the circuit board  12  and a fifth thermocouple junction  30  is affixed near the second element  20   b.  It will be recognized that although only five thermocouple junctions are described here, it is envisioned that other embodiments could have any number of more or fewer thermocouple junctions 
         [0021]    Each of the thermocouple junctions  22 ,  24 ,  26 ,  28 ,  30  includes two thermocouple leads (not shown) that are wrapped inside of a protective sheath  22 ′,  24 ′,  26 ′,  28 ′,  30 ′ that connect the thermocouple junctions to a thermocouple adapter  32 .  FIG. 2  shows that at a point between the circuit board  12  and the adapter  32  each of the protective sheaths  22 ′,  24 ′,  26 ′,  28 ′,  30 ′ merge and are enclosed by an outer cover  31 . It will be understood that the sheaths could merge at any point between the board  12  and the adapter  32 . For example, they could be tied or taped together, molded together, or be collected inside the outer cover  31 . 
         [0022]      FIG. 3  shows four of the adapters  32  attached to a data logger  14 . Each of the adapters  32  has at least one cover  31  protruding from it. It can be seen that the data logger  14  has a tapered width as it approaches one of the ends  33  of the data logger  14 . This tapering allows adjacently coupled adapters to be offset from one another in the longitudinal direction of the data logger, thereby freeing thermocouple leads extending from the adapters to pass unobstructed and keeping the overall width of the data logger/adapter assembly relatively constant. By offsetting the adapters each of the outer covers  31  is configurable to be generally parallel with each other. This embodiment illustrates four adapters connected to the data logger, two on each side, but one of skill in the art will recognize that alternate embodiments could include any number of adapters on each side of the data logger. One skilled in the art will also understand that rather than an outer cover  31  protruding from the adapter  32 , one or more of the protective sheaths  22 ′,  24 ′,  26 ′,  28 ′,  30 ′ could individually extend from the adapter without being collected within the outer cover. 
         [0023]      FIG. 4  shows the adapter  32  in more detail. The adapter  32  includes a housing  36  with two screws  38  situated on a first end  39   a  and a second end  39   b  of the housing for easy opening and closing of the housing. One skilled in the art will recognize that other fasteners or other numbers of fasteners may be substituted for the screws  38 . The adapter  32  includes five thermocouple connectors  40  positioned generally inside of the housing  36  and generally aligned with an elongated connector  41  that extends along the length of the housing from the first end  39   a  to the second end  39   b.  Each of the thermocouple connectors  40  is electrically connected to thermocouple leads (not shown) as will be described in further detail below. The protective sheaths  22 ′,  24 ′,  26 ′,  28 ′,  30 ′ extend from each of the thermocouple connectors  40  respectively and exit the housing  36  from a single location where they are collected into the outer cover  31 . Though five connectors  40  are shown, the housing  36  could include any number of connectors. In the present embodiment the number of connectors  40  could be anywhere between one and five, though in other embodiments the housing  36  could be elongated and the maximum number of connectors within the housing could be increased to meet specified design needs. Further, it will be recognized that although the elongated connector  41  is shown as being a “male” type connector, the connector could also be a “female” type connector and designed to plug into a male port on a data logger. 
         [0024]      FIG. 5  depicts a cutaway version of the adapter  32  showing the internal wiring configuration of the thermocouple connectors  40  aligned in the elongated connector  41  in greater detail. Five thermocouple connectors  40  are arranged inside of the housing  36  including a first end  39   a  and a second end  39   b.  Each connector  40  includes a first thermocouple lead  42  and a second thermocouple lead  44  that extend from a first side  46  of the connector and into one of the protective sheaths  22 ′,  24 ′,  26 ′,  28 ′,  30 ′. For ease of illustration, only one set of thermocouple leads and corresponding sheathing are shown extending from housing  36 , but it is understood that the other thermocouple leads and sheathing are also so situated. The first thermocouple lead  42  extends from a second side  48  of the connector  40  to form a first connecting pin  50 . The second thermocouple lead  44  extends to form a second connecting pin  52 . The connecting pins are separated from each other and held in place by slots in the elongated connector  41  as will be explained with reference to  FIG. 6 . Thus in this embodiment, the first and second connecting pins  50 ,  52  are portions of the first and second thermocouples leads  42 ,  44  that protrude from the thermocouple connector  40 . In alternative embodiments the first and second connecting pins  50 ,  52  are physically separate from the first and second thermocouples leads  42 ,  44  and are electrically connected to them through mechanical compression, welding, or any other manner known in the art. 
         [0025]      FIG. 6  depicts an exploded view of the adapter  32  including a single thermocouple connector  40  and illustrates where it would fit in relation to the housing  36  with an elongated connector portion  41 . Four other thermocouple connectors are shown in dashed lines for the sake of presenting a clear view of the configuration of the housing  36 . The housing  36  comprises a top portion  54  and a bottom portion  56 , each having a first end and a second end  39   a,    39   b.  The bottom portion  56  includes a number of posts  58  defining discrete spaces for a thermocouple connector  40  to occupy when placed inside of the bottom portion. The bottom portion  56  further includes a first slot  60  and a second slot  62  in the elongated connector portion  41  for each thermocouple connector  40 . The first slot  60  and the second slot  62  are configured to support the first and second connecting pins  50 ,  52  of each respective thermocouple connector  40 . The top portion  54  similarly includes a plurality of posts  64  defining discrete spaces for the thermocouple connectors, as well as first and second slots  66 ,  68  that align with slots  60 ,  62  to form a receptacle holding connecting pins  50 ,  52  in position within the elongated connector. 
         [0026]    In this embodiment the one or more thermocouple connectors  40  are placed into the bottom portion  56  as defined by the posts  58  with the first and second connecting pins  50 ,  52  positioned within the first and second slots  60 ,  62 . The top portion  54  is then placed over the bottom portion  56  and the two portions are secured by one or more screws or fasteners as described above. In this manner it is envisioned that the top portion  54  and the bottom portion  56  hold each of the thermocouple connectors  40  securely and separately within the housing  36 . It will be further recognized that the first and second slots  66 ,  68  of the top portion  54  and the first and second slots  60 ,  62  of the bottom portion  56  securely hold the first and second connecting pins  50 ,  52  of each of the respective thermocouple connectors  40  while simultaneously protecting and exposing the first and second connecting pins of that connector within the elongated connector  41 . In this way, the connectors  40  are in electrical contact with a data logger when the adapter  32  is inserted into a port in the data logger as described above but otherwise not susceptible to mechanical damage from bending or striking that could come from activities such as being dropped or handled roughly. 
         [0027]    It will be recognized that this configuration offers several advantages over the prior art. For example, with the thermocouples properly aligned within the adapter, an operator simply needs to snap the entire adapter into the data logger. The adapter is sensitive to orientation and can only plug in one way, making it error proof. Additionally, because multiple thermocouples are plugged in simultaneously, the speed at which the operator can plug and unplug thermocouples from the data logger is greatly increased, and with no concern of errors by plugging a thermocouple into the wrong location on the data logger. Additionally, the adapter can be configured to uniquely identify a given thermocouple quickly and easily to a user or a data logger so that it is readily known which thermocouple junction corresponds to a thermocouple connector at a first position inside of the adapter. 
         [0028]    An additional advantage is that each of the thermocouple connectors is separate from each of the other thermocouple connectors inside of an adapter. A thermocouple including a sheath, a thermocouple junction, thermocouple leads, and a thermocouple connector can be replaced independently of each of the other thermocouples in a given adapter in the event of damage to one or more of the elements. Additionally, if fewer thermocouples are desired or one or more are damaged then each thermocouple is independently removable and replaceable from a given adapter. 
         [0029]    Still further, the adapter allows for easy color coding by affixing labels on the adapter that are matched to color coded sheaths to associate a thermocouple with its respective position in the adapter. 
         [0030]    Finally, by extending the first and second thermocouple leads through the thermocouple connector to serve as the first and second connecting pins, the number of connections and elements in a thermocouple is further minimized. Thus, there are fewer parts to malfunction which can lead to a reduced cost of maintenance and repair. 
         [0031]      FIG. 7  is a flow chart illustrating one method in which the adapter of the present disclosure could be utilized. In the first step  100 , multiple thermocouple connectors are positioned within a single adapter housing. The thermocouple leads are then extended through a single hole located at the end of the housing  102  and the housing is locked down with screws or other securing means. Each thermocouple has a respective thermocouple junction that is positioned on a product, such as a circuit board  104 . A user then snaps the adapter onto a data logger so that the multiple thermocouple connectors are connected to the data logger substantially simultaneously with a single snap-fit  106 . In particular, the male connector of the adapter fits into a female receptacle on the data logger and is keyed to ensure the orientation is correct. Finally, temperature data is collected by passing the product and the data logger through a oven  108  (e.g., conveyor oven). The adapter can then be snapped back off of the data logger Further, though the adapter is discussed as being connected to the data logger with a single snap-fit in step  106 , the snap-fit is merely exemplary and other methods of connection may be used to hold the adapter to the data logger in a secure manner. 
         [0032]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope of these claims.