JPH02211489A - Printed circuit thermocouple mechanism for training and evaluation of apparatus and making and use thereof - Google Patents

Abstract

PURPOSE: To enable the evaluation of a treatment by thermal action by respectively forming a first and second conductor layers capable of constituting a thermocouple on both surfaces of an electrical insulative supporting body and plating these conductor layers with a conductor material through one through-hole, thereby forming a thermocouple joint part. CONSTITUTION: The first conductor material layer 3 consisting of copper, etc., is applied on one surface of the electrically insulative supporting body 1 and the second conductor material layer 5 consisting of constantan, etc., is applied on another surface of the supporting body 1. The two conductor layers penetrating the conductor layers 3, 5 and the supporting body 1 in the position to be formed With the thermocouple joint part 9 are plated with the first conductor material 7 through the through-hole up to the respective pad terminal parts, by which these conductor layers are connected. Then, the potential difference V1 generated by the thermocouple during the production/ repair/reworking work on an emulated electron assembly is monitored and is usable for developing, improving and adjusting the operation of the thermal effect treatment, training operator and evaluation device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is useful for training workers in soldering and unsoldering leads of circuit components on printed circuit boards, and Soldering parts/
The present invention relates to thermocouples for use with printed circuit boards for quantitatively analyzing the operating results of repair, rework and manufacturing equipment used in desoldering, cleaning, preheating and spot welding. More particularly, the present invention provides for the formation of thermocouples for said purpose by standard printed circuit board forming techniques as opposed to standard thermocouple forming techniques, and for a wide range of circuit board types, arrangements and assembly shapes. A method of making and using said thermocouple to emulate.

BACKGROUND OF THE INVENTION U.S. Pat. No. 4,224,744 discloses a circuit arrangement for teaching soldering and a practice circuit board used therein. Here, a practice board is provided having a plurality of terminals, a plurality of temperature sensing devices associated with each terminal are provided at each terminal, and each terminal has a performance or repair skill of the trainee being evaluated. The joints are soldered to monitor the performance of the participants. One type of temperature sensing means disclosed includes a thermocouple in each of a plurality of through holes formed in a printed circuit board. These thermocouples are made of a first material, such as electroless copper, plated through a hole to form a pad or land on each opposite side of the printed circuit board.
consisting of a conductor and a metal foil or wire consisting of iron, constantan, or other conductor metal different from the through-hole plating attached to one of the pads or lands of the plated feed-through conductor, thereby forming a thermocouple junction. A section is formed. Electrical discharge, flame heating, and soldering are used to form these thermocouple joints.

The use of thermoforming, welding, brazing, beading or butt welding techniques is disclosed. Furthermore, the disclosure of the invention includes:
desoldering *Welding, etc., and circuit connections other than those on single or double-sided printed circuit boards (e.g. multilayer boards, ceramic printed circuits, etc.), and plated through-holes, unsupported holes, funnellets, etc. ), eyelets, standoffs, and other types of parts.

Emulation of a wide range of circuit board layouts, molds and assembly geometries in which support materials, thermal properties and other factors vary;
g) “Technologies, uses and structures for manufacturing, reworking or repair processes and their application in the development, evaluation, monitoring and regulation of equipment therefor (i.e. soldering/de-soldering, pre-heating, spot welding, etc.); is not disclosed at all.

U.S. Pat. No. 4,224,744 also details various factors that affect the ability to perform quality rework and repair work on electronic assemblies.
That description is incorporated herein for the sake of brevity. These factors include training to develop the necessary skills and experience by showing workers how to properly operate and handle soldering irons or other rework and repair equipment. Not only human factors such as best practice, but also factors other than worker issues, such as characteristics of rework and repair equipment (e.g. soldering iron tip temperature, its recovery speed, etc.) and components and printed circuits. This includes properties of the plate (e.g. temperature, thermal conductivity, specific heat, etc.). As a result, in order to properly train and evaluate workers, it is desirable to be able to simulate as realistically as possible a wide range of conditions that workers are likely to encounter. Also, even with the best training, work can become too crowded due to excessive dwell times or temperatures, resulting in
Damage to printed circuit boards in the form of lifted pads, damage to plated through-holes, or in extreme cases damage to fiberglass laminates due to equipment-related factors. Damage to the printed circuit board may occur. Therefore, or1
It would also be desirable to provide a means for evaluating new devices, especially automated devices, for example by analyzing the temperature distribution to which soldered joints are exposed during soldering/de-soldering processes.

The usual method of inspecting solder joints is visually. However, such qualitative analysis methods are not effective. This is because looking at the physical appearance of a soldered joint does not tell you the highest temperature to which the joint has been exposed, and the length of time the joint has been exposed to that highest temperature. on the other hand,
In order to perform a quantitative analysis of the temperature conditions to which the junction is exposed, thermocouples must be attached to circuit pads and/or component leads, so that the temperature is recorded using a computer data recording system. . However, spot welding is commonly used to attach thermocouples to leads or pads, which is a difficult process and can become cumbersome if a large number of joints have to be inspected. , which is expensive (costing about $5 for each couple).

(Purpose of the invention) The object of the present invention is to provide molds and support materials for thermocouple components.

It is an object of the present invention to provide a thermocouple mechanism and method that can easily and inexpensively emulate a wide variety of printed circuit board types, arrangements, and assembly geometries in which thermal properties and other factors vary.

Another object of the invention is to adapt standard printed circuit board formation techniques to the above purpose.

Another object of the invention is to provide thermal treatment (therva treatment).
lly afTecting processes)
, a method of using the thermocouple arrangement of the present invention in the development, evaluation, monitoring, and regulation of processing equipment and associated human factors.

Yet another object of the invention is the actual thermal action manufacturing;
rework and repair processes (e.g. soldering, desoldering, cleaning, fluxing,
Preheating, heat compression, bonding.

The aim is to enable quantitative analysis of the temperature distribution occurring in an emulated printed circuit board assembly during the execution of spot welding and other processes).

Said other processing is for evaluating the processing and processing equipment and for testing and repair through the measurement of the temperature to which the solder joints 1 part lead and/or support material of the printed circuit board assembly is exposed during processing operations. Thermal effects can be applied to the assembly for training or recertification of personnel.

(Configuration of the Invention) The above object of the present invention is achieved by various embodiments of the present invention having the following configurations. That is, the first metal such as copper
a second layer of a second conductive material different from the first conductive material, such as constantan, as opposed to standard thermocouple forming techniques; At least one other surface of the support is applied using conventional printed circuit board forming techniques. A hole is drilled through the conductor layer and the support material at the location where the thermocouple junction is to be placed, and the two layers of conductor pass the first conductor through the through hole to the pad terminal portion of each of the conductor layer. Electrical connections are made by plating with material.

The potential difference developed by the thermocouple during manufacturing/repair/rework operations on the emulated electronic assembly is monitored and thermally processed.

Used to develop, improve, or adjust the operation of training personnel or evaluation equipment. Therwal Was
S) Various treatments can be evaluated, including different combinations of shape, heat source location and type, and also thermocouple location.

(Examples) The present invention will be described in more detail based on the following examples with reference to the attached drawings.

In FIG. 1, a basic thermocouple arrangement is shown for providing temperature data obtained from a test printed circuit board rework, repair or manufacturing operation that includes at least one thermally active treatment. This thermocouple arrangement is described in Section 4 of the aforementioned U.S. Pat.
It can be used to train inexperienced personnel who are assigned to solder in the manner of No. 224,744, to re-certify experienced repair personnel, or to evaluate new rework and repair equipment. The term "thermal action treatment" refers to any number of treatments used in the reworking, repair, or manufacturing of electronic assemblies that affect the structure, usability, and/or appearance of various parts of the electronic assembly through the effects of temperature. (e.g. soldering, desoldering, cleaning, flashing (fluxlng))
, preheating, thermal compression, bonding, spot welding,
Cooling, and through-hole or surface mounting are used to refer to other processes involved in installing, removing, and replacing parts. Although the embodiments of Figures 1-3 are only described using a single thermocouple junction, they emulate electronic assemblies (including bare circuit boards and circuit boards in production). It should be noted that the thermocouple arrangement according to the present invention for use with thermocouple junctions has at least as many thermocouple junctions as the number of leads of the components with which they are used.

The printed circuit thermocouple arrangement of FIG. 1 includes an electrically insulating support 1 consisting of a standard circuit board made of glass reinforced epoxy or other suitable material.

A first layer of conductive material, such as copper, is applied to a first surface of support 1 and a second layer of conductive material, such as constantan, different from the first conductor material, is applied to the opposite side of support 1. has been done.

These layers of conductive material are made using conventional printed circuit board manufacturing techniques. For example, approximately 0.002 inches (0,
A copper foil 3, approximately 0.005 cm thick, is laminated to one side of the support, and a constantan foil 5, approximately 0.002 inch (0.005 cm) thick, is laminated to the other side of the support. A hole is provided through said foil and support laminate at the location where the thermocouple junction is to be placed, and pad terminals in the form of lands are formed around the hole on both sides of the support 1 by photomasking techniques. has been done. Electroless copper 7 is plated over the pads formed as a photomasked pattern, through the copper foil and constantan seedlings, and through the holes. Copper plating 7 electrically and mechanically connects with the copper foil and constantan foil to form a T-type thermocouple junction. Signal monitor connections and trace interconnections extending between the signal monitor portion and the lands are formed on both sides by photomasking techniques, and unnecessary copper and constantan foils are removed using a suitable etching agent such as ferric chloride. The circuit structure pattern is completed.

After said step, a thermocouple junction 9 is formed at the interface between the thermocouple pad terminal part of the printed circuit pattern of constantan 5 and the plated copper 7.

In this way, in each case the constantan conductive material is formed into an interlocking printed circuit pattern. On the other hand, the copper-to-copper electrical connection is formed at the interface 11 between the copper layer 3 and the plated copper 7 on the opposite side of the insulating support 1, so that the copper layer 3 is connected to the mating interconnected printed circuit pattern. Is there or a load?

If thermal isolation or instrument sensitivity requirements permit, the copper may remain in its original sheet form, such that the copper layer spans at least the same area as the printed circuit pattern will be formed. The corresponding side of the support 1 can be completely covered.

Figure 1 shows multiple leads (in Figure 1, one lead 13).
When installing the electronic component 13 in the through-hole (only part a is shown), it is sometimes necessary to use a soldering tool T such as a soldering iron.
The thermocouple arrangement used to obtain data regarding the temperature distribution at the point of the solder S applied by the method is shown. Here, a wave-type soldering machine used for mass production of through-hole printed circuit boards (in that case, the thermocouple mechanism is reversed to the direction shown in Figure 1, and the molten solder bath of the wave-type soldering machine is It should be noted that other soldering tools and automatic soldering equipment, such as a thermocouple assembly (such as a thermocouple assembly), may also be used with the thermocouple arrangement of the present invention.

In most cases, monitoring of the signal from the thermocouple junction may be accomplished using a typical Prindro roadboard edge connector or other conventional connector. However, if the thermocouple arrangement is placed above a wave-type solder bath, the output connections can only be made on the top surface of the circuit board. In FIG. 1 a simple voltmeter is shown schematically as an example of a power quantification means used to measure the temperature-related potential difference occurring at the thermocouple junction 9. It's nothing more than that.

In addition to soldering work, solder removal processing after parts are attached can also be evaluated using the thermocouple mechanism of the present invention. In that case, move the desoldering tool around the component leads on the side opposite to the component body (i.e., the solder side in the case of through-hole attachment), pointing toward the solder. A desoldering device is then activated to apply heat to the solder joint, heating the solder above its melting point and then using a vacuum to remove the solder from the hole. Other thermal treatments can be monitored in a similar manner.

In the embodiment of Figure 1, if the component is to be inserted into the constant, the heat required to melt the solder in the hole is transferred through the copper plating, the component leads, and the solder itself. . As a result, temperature measurements made during the desoldering process are biased toward the component side of the circuit board. This is because the thermocouple junction is on the component side. In circuit configurations with small lands and traces and small component leads, the temperature difference from the solder side to the component side is small. However, if for example large circuit traces or lands are placed on the component side, there will be a measurable temperature difference between the solder side where the heat is applied and the component side where the heat is sensed by the thermocouple junction 9. . This temperature difference means that the heat needed to raise the temperature of a large circuit area to the temperature at which the solder melts is transferred through the plated through-holes, the component leads, and the solder, and the through-holes are routed through the circuitry on the component side. It is based on the fact that it has a small heat transfer coefficient compared to the heat required to raise the temperature of the structure.

This low heat transfer coefficient impedes the flow of heat from the solder side to the component side, thereby creating a noticeable temperature gradient between the two sides. Therefore, under such circumstances, the thermocouple junction 9 is placed on the side of the support 1 whose temperature is to be monitored.

That is, the component 13 is either through-hole mounted on the side shown in FIG. 1 or surface mounted on the opposite side (as explained below with reference to FIG. 2). On the other hand, when using circuit configurations with small lands and small circuit traces and/or small component leads, the first
Good results can be obtained by mounting the components on either side of the configuration shown.

FIG. 2 shows a thermocouple arrangement for monitoring temperature data with thermocouple thermal sensors placed on each of the opposite sides. Here, the electrically insulating support 21
is formed from a plurality of circuit board layers 21a, 21b, and a layer of a first conductive material 23 (eg, copper) is formed on the interface between a pair of circuit board layers 21a, 21b of support 21. Second conductor material (e.g. constantan) 2
The printed circuit patterns 5a and 25b are attached to the support 21.
are electrically and mechanically coupled to each other by plated through electrical connections 27 formed on each of the opposite exterior surfaces of the . This corresponds to the conductors 3, 5 and electrical connections 7 in FIG. As a result, a pair of thermocouple junctions 29a, 29b are formed at the interface between the electrical connection 27 and the layers 25a, 25b, and an electrical connection 31 is formed between the first conductive layer 23 and the through-hole of the electrical connection 27. Formed at the interface between plating. First conductor 23
The inner layers of the circuit board layers 21a, 21 are as shown.
Whether it is a continuous sheet of foil filling the interface between b or a connected pattern of traces with gaps filled with insulating material,
As mentioned above, it depends on the load, thermal isolation and sensitivity conditions (which in most cases makes the pattern of all conductor layers preferred).

FIG. 2 also shows surface attachment of electronic components 33 via leads 33a. For this reason, if the diameter of the through hole is not extremely small, the first conductor material (
A plug 35 of copper, for example, is inserted into the through-hole, or at least the hole is closed or made to a very small diameter by melting solder into the hole on the side for mounting the component. However, in the embodiment of FIG. 2, through-hole mounting as described in FIG. 1 may also be utilized.

The embodiment shown in FIG. 2 is a contact that makes it difficult for a first heat source, such as hot air, brought to the side of the component in FIG. Manufactured when an auxiliary heat source is used with a printed circuit board that has a ground or other heat dissipating part (heat absorbing part),
This is particularly advantageous when evaluating final processing or repair treatments.

In such cases, an auxiliary heat source can bring the circuit board to a pre-melting temperature (
It is used to compensate for unwanted heat absorption, such as by increasing the temperature to 250'F. For example, if a large thermal mass is present on the bottom side of the circuit board due to the ground plane,
Due to heat absorption by the mass, the first heat source cannot provide enough heat to raise the temperature of the lead portion of the component to the solder melting temperature.

Therefore, in addition to the first heat source placed on the component side of the circuit board (upper part in FIG. 2), a preliminary heater can be used at the bottom of the circuit board to compensate for the heat absorption. Thus, by using the embodiment of FIG. 2 in which thermocouple junction type sensors are provided on both sides of the circuit board, a combination of emulated heaters is used at the top and bottom of the circuit board. The effects of this can be evaluated. Alternatively, only one or the other of the heaters can be evaluated separately at the top and bottom of the support 21. These temperatures can be measured using a voltmeter (schematically indicated by Vl and Vz in the figure) which measures the potential difference produced by the thermocouple junctions 29a, 29b.

Any number of additional circuit layers can be added by examining the temperature gradient to provide a more detailed analysis of the temperature distribution. For example, FIG. 3 shows a printed circuit thermocouple arrangement according to the present invention in which electrically insulating support 41 is subdivided into four circuit board layers 41a-41d with conductor layers formed on each side of the circuit board layers. ing.

In this case, the central conductor layer 43 is formed of a first conductor material such as copper, and the other conductor layers 45a to 45d are all formed of a second conductor material different from the first conductor material (such as constantan). It is formed.

Layers 45a-45d all consist of interlocking printed circuit patterns made as described above, and layer 43 of first conductive material preferably comprises interlocking printed circuit patterns, but as described in other embodiments, interlocking foils. It can also be used as a layer. The temperature gradient is measured by a voltmeter (1-V4 in FIG. 3) that measures the potential difference generated at the thermocouple junctions 49a-49d.

Although in the embodiments of Figures 1-3 a simple voltmeter is shown as a means for monitoring the potential difference developed at the thermocouple junction, it should be noted that various other more sophisticated means may be used. is clear. For example, U.S. Pat.
The type of analyzer and display disclosed in No. 24.744 may be used, or other types of configurations may be used to suit the particular situation. Furthermore, data is obtained throughout the entire operation process, rather than only during a specific thermal treatment of a manufacturing, rework or repair operation.

4-6 illustrate printed circuit pattern masks used to form the conductor layers of the printed circuit thermocouple arrangement of FIGS. 1-3. In FIG. 4, the pattern mask BO includes a thermocouple pad terminal portion 62 for each lead.
and the thermocouple pad terminal section 62 to the signal monitor connection section 66.
is shown as a 16-pin DIP with trace interconnects 64 of the same width connecting to. Positioning frame corners 88 of mask 60 including corner frames 68
Note that the portions that are not inside are removed by an etchant as described above with respect to the process of making the thermocouple arrangement of the present invention.

In FIG. 5, pattern mask 70 is also shown as a 16 pin DIP. However, in this embodiment, the thermocouple pad terminals monitored by trace interconnects 74 and connections 7B are comprised of small area/mass lands similar to those of FIG.
gives a stepped circuit area over the terminal portion 72b consisting of large areas/mass lands. As the circuit area increases, the heat load increases, so the larger the circuit area, the longer the time required to heat the solder joint.

Accordingly, the pattern mask shown in FIG. 5 can be used to emulate a circuit board with a ground plane attached to wide traces or pads. It should be noted that in addition to this technique, other techniques can be used to simulate a ground plane (or other heat dissipation feature) on or within a printed circuit board consisting of a single layer or multiple layers.

For example, with reference to FIG. 3, the diameter of the through-hole and/or the thickness of the plating 47 on the wall of the hole can be varied. As a result, electronic assemblies and processes that produce complex temperature distributions can be emulated. For example, many of the thermal characteristics of a multilayer printed circuit board can be emulated by a much less expensive double-sided circuit board according to the present invention.

FIG. 6 shows a pattern mask 80 for a large surface mount component having 17 leads on each side. Here, terminal portions 82a forming thermocouple junctions at three spaced locations on each side (e.g., at the 3rd, 8th, and 15th leads) and terminal portions 82a on each side are shown.
terminal portion 112b spaced 0.2 inch from the center of the row of
is provided. Such a configuration allows complex temperature distributions of the component and surrounding areas obtained during various processes. Although 1B thermocouples are used in FIG. 6 (or in FIGS. 4 and 5), the number of these thermocouples depends on the amount of space available and on the lead traces 84 and monitor connections 86. limited only by the intercommunication through which The use of a thermocouple arrangement of the type shown in Figure 6 is not limited to thermocouple junctions in the pattern on parts that are directly exposed to the heat action treatment during a particular emulation, but transfer to parts that are not directly subjected to the action. It is particularly advantageous in the evaluation of densely packed circuit board assemblies to measure the thermal effects caused by the thermal effects.

Note from the above that various combinations of (a) thermal vas geometry, (b) heat source location, and (e) thermocouple junction location can be created in the present invention. Thereby, various printed circuit board sizes, types, arrangements and assembly geometries can be emulated, and various soldering/desoldering processes,
or other manufacturing, repair or rework operations that require the application of heat to printed circuit board features.

Further, the printed circuit board thermocouple arrangements according to the present invention are all constructed in such a way that the thermocouple junctions are formed on an electrically insulating support simulating the effects at different locations on different types of printed circuit boards. Although described, it should be noted that other configurations are possible with conventional printed circuit techniques for forming PA couples. for example,
Printed circuit thermocouples may be formed within a simulated chip, where the number of printed circuit thermocouples corresponds to the number of chip leads, and printed circuit thermocouples may be formed within a simulated chip, where the number of printed circuit thermocouples corresponds to the number of chip leads; It is also possible to have fewer circuit thermocouples than the number of chip leads, with some of the chip leads connected to a heat source and the rest to a power analyzer. In this way, temperature data for manufacturing, repair or rework operations carried out on printed circuit boards are obtained in such a way that they reflect the thermal effects directly experienced by the electronic components themselves, which can be used to train and train personnel. The present invention can be used to develop, control and monitor thermal processes such as soldering, soldering, etc., using an analyzer capable of storing time and temperature curves, as described, for example, in U.S. Pat. No. 4,224,744. The processing equipment can be evaluated by

Those skilled in the art will recognize that the materials described for use in the thermocouples of the present invention are one example and that many alternatives may be used. For example, instead of using a support consisting of a glass-reinforced epoxy circuit board, a ceramic, polyimide or polyimide/"Kevlar" laminate can be used.

Additionally, instead of forming a T-type thermocouple junction, a K-
Type or J-type thermocouple junctions can be formed using chromel/alumel or iron/constantan conductive foils, respectively.

The above description also includes examples of preferred uses of the invention for printed circuit thermocouples according to the invention and methods of making and using the same (for purposes such as training of personnel and evaluation of equipment, as discussed above). It should be noted that they are illustrative only and do not reflect the entire application of the invention.

That is, the thermocouple arrangement of the printed circuit thermocouple arrangement according to the invention can be used in almost all cases where it is necessary to obtain a temperature distribution due to thermal effects. For example, heat blocking or heat loss effects can be achieved by covering one or more surfaces of an object with a printed circuit thermocouple arrangement according to the invention having a suitable pattern of thermocouples, in a manner similar to that by infrared photography techniques. It can be evaluated.

Furthermore, (for example polyimide or polyimide/"Ke
By using a flexible circuit board-type support (composed of "Vlar"), the thermocouple arrangement of the present invention can be easily applied to arcuate and other non-flat surfaces.

Still further, the method of manufacturing thermocouples according to the invention using printed circuit technology provides an alternative to conventional thermocouples for use as a replacement for standard thermocouples in all applications that previously used small individual thermocouples. Offer new, low-cost products. In particular, a single large support can be formed with an infinite number of individual thermocouple junctions according to the invention, said support on which the thermocouples are formed having a corresponding number of individual thermocouple junctions. thermocouple element. Each of the thermocouple elements includes a corresponding one of the thermocouple junctions. In this way, thermocouple element manufacturing according to the invention requires a fraction of the costs associated with conventional techniques. Here too, the use of thin flexible support materials is advantageous.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a printed circuit thermocouple arrangement according to the present invention for a simple circuit board with through-hole mounting components; FIG. 2 is a three-layer printed circuit board with surface mounting components; FIG. 3 is a cross-sectional view of a portion of a printed circuit thermocouple arrangement according to the invention for monitoring temperature on both sides of a multilayer printed circuit board; FIG. A cross-sectional view showing a part of the pair mechanism, and FIGS. 4 to 6 are views each showing an example of a photomask pattern for manufacturing a printed circuit thermocouple according to the present invention. 1, 21.41...Support 3...Copper foil 5...
・Constantan foil 9, 29a, 29b...Thermocouple junction 23...
First conductor material 25a, 25b...Second conductor material 80, 70.
...Pattern mask Figure 1 ``1re 3゜rtransport-e2゜1999 Patent Application 2. Title of Invention Relationship with Case No. 306.343 of January 18, 2000

Claims (1)

Claims: At least one on an electronic assembly by emulated manufacturing and/or rework and/or repair operations.
1. A thermocouple arrangement for obtaining temperature data from a thermal action process, comprising: an electrically insulating support; a layer of a first conductive material applied to a first surface of the support; The second material is different from the material.
one or more printed circuit patterns formed on one or more other surfaces of the support, the printed circuit patterns comprising a thermocouple pad terminal portion;
a circuit arrangement having a signal monitor connection and a trace interconnection extending between the thermocouple pad terminal and the signal monitor connection; A thermocouple pad terminal is connected to the layer of first conductive material by an electrical connection of the first conductive material, the electrical connection connecting the thermocouple to the corresponding thermocouple pad terminal. extending through the support between a thermocouple pad terminal portion of the printed circuit pattern of the second conductive material and the layer of the first conductive material to form a joint; Characteristic thermocouple mechanism.