The method for surface mounting electronic components on a printed circuit board

 

(57) Abstract:

The invention can be used when surface mounting of electronic components (EC) on the PCB (PP) in electronic and electronic equipment. Download EK in drives make with respect to the location of their conclusions regarding the orientation of the pads, PP. Produce the capture and transfer of EC drive in the installation area on the PP. Welded conclusions produced using a sequential discharge of the capacitor banks on linearly increasing with the law. In the welding process to provide continuous remote non-destructive quality control of each connection on the measurement of the intensity of infrared radiation from the welding zone with possibility of adjustment of the welding modes depending on the condition and geometry of the welded surfaces. Welding of the conclusions of the EC to the contact pads PP carry out three welding electrodes, forming two pairs of dual electrodes arranged in mutually perpendicular planes. The method provides the expansion of technological possibilities of installation and increased productivity.

The invention relates to electronic and radio-electronic equipment is(PP) production, for example, radio and TV.

There is a method of resistance welding along.with. 1199532, CL 23 To 11/24 from 03.02.84, publ. in BI 47, 1985. the Method consists in forming a pulse of welding current and carrying out heating, welding and annealing of the welded components by successive discharge n battery capacitor to the primary winding of the welding transformer, the welding current pulse is formed by linearly increasing the law by successive reduction of inductance L discharge circuit on the value of L/n and increase capacity with each successively discharged capacitor Bank on the value of the JV, and the time sequence of discharge of the capacitors remain constant.

The disadvantage of this method is that it does not control the quality of the connection and adjustment of welding modes during the welding process, depending on the state of the elements to be welded, that does not guarantee high quality of each connection and allows you to use the automatic technical process.

The closest to the technical nature of the claimed is a method for surface mounting of electronic devices on the printed circuit Board p is raissadat sample EC of the drive, capture and transfer them to the installation area on the PP, the correction of the location of the conclusions of the EC relative to the coordinates of the contact pads (CP) on PP, fixation EC on the PP pre-welding of at least two conclusions, the subsequent welding of all other conclusions using a sequential battery discharge capacitor to the primary winding of the welding transformer by linearly increasing with the law, in the welding process to produce continuous remote non-destructive quality control of each connection on the measurement of the intensity of infrared radiation (IR radiation) from the welding zone with possibility of adjustment of the welding modes depending on the state of the welded surfaces.

The disadvantage of the prototype method is that it does not:

- possibility of installation on KP PP EC, the conclusions of which are located around the perimeter of its body, as in one and in two mutually perpendicular positions;

- possibility of installation on KP PP EC, conclusions which are located on opposite sides of its body, in two mutually perpendicular positions.

All this reduces its functionality. In the apparatus of the present method, such Montt is the turnover reversal PP 90oregarding the EC moved to the installation area, as PP is mounted on a stationary table. In addition, the welding head is equipped with two welding electrodes, provides welding of the conclusions of the EC with KP PP only in one position, a given spatial position of these electrodes.

Solved technical challenge is to develop a method for surface mounting EC on the PP continuous and automatic, which would provide more opportunities and increase productivity by reducing the time for correction of EC on KP PP.

The expected technical result of implementing the inventive method is expressed in the possibility of welding conclusions EK:

- located around the perimeter of the sides of its body in one position, and in two mutually perpendicular positions;

- located on two opposite sides of its body in two mutually perpendicular positions.

The technical problem is solved by a method for surface mounting of electronic components (EC) on the PCB (PP), providing execution in automatic mode, the entire set of operations of assembling the collection is the position of the conclusions of the EC relative to the coordinates of the contact pads (CP) on PP, fixation EC on the PP due to the preliminary welding, at least two of any findings EK at KP, PP, subsequent welding of all other conclusions EC on KP PP using a sequential discharge of the capacitor banks on linearly increasing with the law, while the welding process is continuous remote non-destructive quality control of each connection on the measurement of the intensity of infrared radiation from the welding zone with possibility of adjustment of the welding modes depending on the condition and geometry of the welded surfaces, the loading of EC in the drives is done with respect to the location of their conclusions regarding the orientation KP PP, and welding of the conclusions of the EC to KP PP carry out three welding electrodes, forming two pairs of dual electrodes arranged in mutually perpendicular planes.

Can be installed on KP PP conclusions EC, which are located on its body around the perimeter or on two opposite sides, in one or in two mutually perpendicular positions, provided the download EK in drives with the location of their conclusions regarding the orientation KP PP for their installation. The possibility of welding of the conclusions of the EC with KP PP, which is attachment or in two mutually perpendicular positions, provided with three welding electrodes, forming two pairs of dual electrodes located in two mutually perpendicular planes.

Way surface mount EC on PP is implemented as follows. EC, which must be mounted on the PP in different positions, is loaded into the drives with respect to the location of their conclusions regarding the relevant KP PP. Then EK using capture manipulator is extracted from one or the other of the drive depending on what KP PP, it is intended to be installed, is transferred to the installation area, carry out correction of pins relative to the coordinates of KP on PP and hold them in the process of welding at least two conclusions. Fixed table PP move to the installation area and set so that the conclusions of the EC combined with KP PP. The welding head is moved to a position to consistently produce welded two diagonally-opposite conclusions with EC KP PP. Welding of the conclusions of the EC to KP PP carry out one of the two pairs of twin welding electrodes, which is formed by three electrodes and are located in two mutually perpendicular planes. Thereafter, the grippers of the manipulator release of EOI program for sequential welding of the other conclusions of the EC with KP PP. In the welding process to produce continuous quality control connection of each output radiation flux IR-izlucheniya from the welding zone, and, if necessary, is the automatic adjustment of the welding modes within providing the specified connection parameters. These limits are predefined calculation and experimental way. After completion of the welding of the conclusions of one of the EC process is repeated for the next EC in the above sequence. Welding modes are provided automatically by the power source by linearly increasing the law of passing high-frequency current. The law of attachment energy form for each connection with consideration of the welded material and geometry of the conclusions of the EC and PP.

Inspection of welding process of the conclusions of the EC to KP PP was implemented on the automatic installation dimensions 1000800 mm height 1400 mm it installed PP size 300200 mm, which is equipped with 30-35 chip 3-5 types of series 133, 134, 564, chip 3-5 types of series 133, 134, 564.

The time from the initial operation of the installation into a finished Board was 12.5 minutes Hand soldered Assembly similar Board requires about 10-12 hours As all connections are controlled by controllers is x2">

When implementing automatic installation of the proposed method welding to KP PP of the same dimensions and with the same number of chips, the conclusions of the EC, which are located around the perimeter of the sides of its body or with two mutually opposite sides of its body, in one position or in two mutually perpendicular positions, performance, and quality of installation must be the same.

Thus the claimed method meets all the requirements defined by the technical task.

The method for surface mounting of electronic components (EC) on the PCB (PP), including loading and fetching EC of the drive, capture and transfer of EC in the installation area on the PP, the correction of the location of the conclusions of the EC relative to the coordinates of pads on the PP, fixation EC on the PP due to the preliminary welding, at least two of any of the conclusions of the EC on the contact pads PP, subsequent welding of all other conclusions of the EC on the contact pads PP using a sequential discharge of the capacitor banks on linearly increasing with the law, in the welding process to provide continuous remote non-destructive quality control of each connection on s depending on the state and geometry of the welded surfaces, characterized in that the loading of EC in the drives is done with respect to the location of their conclusions regarding the orientation of the pads, PP, and welding of the conclusions of the EC to the contact pads PP carry out three welding electrodes, forming two pairs of dual electrodes arranged in mutually perpendicular planes.

 

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FIELD: resistance spot welding; mechanical engineering.

SUBSTANCE: welding current interrupter of digital sampler is connected to circuit of primary winding of welding transformer. Current and voltage pick-ups are connected with analog multiplier. Pulse integrator and electric energy number of quantum binary counter are connected in series. Output of binary counter is connected with electric energy current value indication unit and binary-decimal code converter. Input of code comparing unit is connected with binary-decimal code converter and electric energy number of quantum presetting unit. Current pick is made on the base of Rogovsky's belt. Impulse multiplier is used as analog multiplier. The multiplier has to be the source of rectangular-shaped pulses used for controlling current interrupter which is made on base of triac. Current interrupter control unit is connected with one output of pulse multiplier.

EFFECT: improved precision of portioning of heat pulse; widened range of welding current to be measured; improved quality of welding.

1 cl, 2 dwg

FIELD: contact spot AC-welding with use of welding cycle regulator having thyristorized module.

SUBSTANCE: method is realized on change of conductance angle of thyristors. Method comprise steps of preliminarily determining reference points of welding electric currents for each phase of spot welding process; according to said points calculating regression models of amplitude curves of welding currents and calculating values of conductance angle of thyristors depending upon maximum value of welding current, frequency of supply mains, turning-on angle of thyristors, phase shift angle and coefficients of power type polynomial; writing in modules for controlling welding current preliminarily registered in regulator of welding cycle values of conductivity angles of thyristors for their further using at controlling welding current.

EFFECT: enhanced quality of welded joints due to controlling conductivity angle of thyristors for each half-period of welding current at different phases of welding process.

3 dwg

FIELD: welding processes and equipment, namely apparatuses for controlling process of resistance spot welding.

SUBSTANCE: method comprises steps of measuring at each period in secondary circuit acting values of electric current and voltage drop between electrodes; calculating power factor cos φ and heat quantity liberated for period; controlling ignition angle of thyristors. Voltage drop on electrodes is measured at maximum value of welding electric current. Heat quantity liberated for period is calculated while taking into account measurement results by means of expression: Qi = I2act(Uel/Imax)t, where Qi - heat quantity liberated between electrodes in i-period of welding current, J; Iact - measured for period acting value of welding current, A; Imax - maximum value of welding current for period, A; Uel - voltage drop between electrodes measured at moment of maximum welding current, V; t - time duration of welding current period, s. Calculated heat quality is compared with predetermined one and according to comparison result in next period ignition angle of thyristors is changed while satisfying condition: (Iact(α i+1)/In (cosφ)} = (Iact/In(cosφ)) x (Qset/Qi)0,5 where Qset -preset heat quantity liberated for period, J; Iact(α i+1) - calculated for given apparatus acting value of welding current for next period depending upon set ignition angle of thyristors αi+1 and power factor cosφ, A; In(cosφ) - acting value of full-phase current depending upon power factor cosφ, A.

EFFECT: enhanced quality stability of spot-welded joints due to elimination or weakening of disturbances.

2 dwg, 1 ex

FIELD: welding processes and equipment, possibly controlling welding current in contact welding AC machines due to initially setting in control unit calculated angle of thyristor ignition.

SUBSTANCE: before starting welding process at short circuited electrodes in order to determine parameters of welding circuit such as active and inductive resistance values welding transformer is turned on at predetermined angles of thyristor ignition. Acting value of secondary current of welding circuit is measured for predetermined angle values and depending upon measured value graphs of functions Xk = f(Rk) (1,2,3,4) are plotted. Coordinates of crossing point of said graphs corresponding to values Rk and Xk of welding circuit are determined. At welding ignition angle of thyristors is changed in such a way that to make mean value calculated at taking into account Rk and Xk for welding cycle corresponding to preset one.

EFFECT: simplified process for determining phase control parameters at program control of thyristor ignition angle.

1 dwg, 1 ex

FIELD: contact welding processes and equipment, namely automatic control of welding machines.

SUBSTANCE: method comprises steps of determining power coefficient cosφ in each period of welding current and value of heat release in zone electrode-electrode. Value of heat release is calculated according to expression qi = (I2)2 x r el-el x 0.02, where rel-el - resistance of zone electrode-electrode; I2 -acting current value in secondary circuit. If calculated value differs from preset one, decision for performing correction of thyristor ignition angle in next period of welding current is assumed. Angle of thyristor ignition is determined according to given formula αi+1i·(√q/qi) +(a0/a1)·(√q/qi-1) where q - preset heat input for period; a1 , a0 - coefficients determined empirically on base of power coefficient; αi - thyristor ignition angle in current period.

EFFECT: improved quality of spot-welded joint having predetermined geometry size regardless of state of electrode and welded part surface in the result of stable heat release in interval electrode-electrode.

2 cl, 3 dwg, 1 ex

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