HK1189193B - Application method of liquid material and application device - Google Patents

Description

Method and apparatus for applying liquid material

Technical Field

The present invention relates to a method, an apparatus, and a program for applying a liquid material, which fill a gap between a substrate and a work placed thereon with the liquid material discharged from a discharge device by utilizing a capillary phenomenon, and more particularly, to a method, an apparatus, and a program for stabilizing an application shape while correcting a change in a discharge amount without changing a moving speed of the discharge device in an underfill (underfil) process of a semiconductor package.

In the present specification, the "discharge amount" refers to the amount of the liquid material discharged from the nozzle in one discharge, and the "application amount" refers to the amount of the liquid material required in a certain range (for example, an application pattern or an application region) where a plurality of discharges are performed.

Background

As one of the mounting techniques of a semiconductor chip, there is a technique called a flip chip (FlipChip) method. In the flip chip method, a projection-like electrode (bump) 31 is formed on the surface of the semiconductor chip 30 and directly connected to an electrode pad 32 on the substrate 29.

In the flip chip package, in order to prevent the connection portion 33 from being broken by concentration of stress on the connection portion 33 due to a difference in thermal expansion coefficient between the semiconductor chip 30 and the substrate 29, a resin is filled in a gap between the semiconductor chip 30 and the substrate 29 to reinforce the connection portion 33. This process is called underfill (see fig. 7).

The underfill process is performed by applying a liquid resin 34 along the outer periphery of the semiconductor chip 30, filling the resin 34 into the gap between the semiconductor chip 30 and the substrate 29 by capillary action, and then heating the resin 34 in an oven or the like to cure the resin.

In the underfill process, it is necessary to take into account the change in viscosity of the resin material with the passage of time. This is because, if the viscosity becomes high, the discharge amount from the material discharge port decreases, and the capillary phenomenon becomes insufficient, which causes a problem that an appropriate amount of the material is not filled in the gap. In a step in which the viscosity changes drastically, for example, after 6 hours, the discharge amount may be reduced by 10% or more. Therefore, it is necessary to correct a change in the discharge amount due to a change in viscosity with time.

However, for the filling of the resin material used in the underfill process, generally, a dispenser (dispenser) is used. As one of such dispensers, there is a jet (jet) type dispenser that ejects and discharges droplets of a liquid material from a nozzle.

A method of performing the bottom filling process using a spray type dispenser is disclosed, for example, in japanese patent laid-open No. 2004-. That is, patent document 1 discloses a method for discharging a viscous material onto a substrate using a jetting type dispenser, including: preparing the total volume of the viscous material to be discharged and the length of the viscous material to be discharged; acting in a manner to coat a plurality of droplets of viscous material onto the weight; generating a feedback signal indicative of the weight of the plurality of droplets of viscous material applied to the weight scale; the maximum relative velocity between the dispenser and the substrate is determined so as to discharge the total volume of the viscous material over the length.

In addition, in patent document 1, the method further includes: determining respective volumes of the plurality of droplets of the liquid material; determining the total number of droplets required to be substantially equal to the total volume; determining a distance between droplets required to substantially uniformly distribute droplets of the viscous material over the length; and determining a rate value of droplets of the viscous material discharged from the dispenser in order to discharge the total volume of the viscous material over the length at the maximum relative velocity.

Next, if underfill is performed, a fillet (fillet) portion 35 filled with the liquid resin 34 is generated at a corner portion formed between the side surface of the semiconductor chip 30 and the substrate 29. The round portion 35 is referred to as a round (see fig. 8). If the fillet 35 is not uniformly formed, there are problems such as the fillet 35 causing air to enter from a small portion and entrapping air bubbles, the resin 34 being exposed up to the coating-prohibited region around the coating target chip 30, and the semiconductor chip 34 being damaged during heat curing. Therefore, the rounded corners 35 need to be uniformly formed with a certain width 36 and height 37.

The reason why the round corners 35 are not formed uniformly is that the degree of penetration varies depending on the density of the arrangement of the bumps 31. Generally, the liquid resin 34 permeates more rapidly in the portions where the bumps 31 are densely arranged, and the liquid resin 34 permeates less rapidly in the portions where the bumps 31 are sparsely arranged. Therefore, if a certain amount of coating is performed, the fillet 35 having the uneven width 36 or height 37 is formed due to the difference in the degree of penetration as described above, and the shape of the fillet 35 is disturbed.

Another reason why the rounded corners 35 are not formed uniformly is a speed change in the coating operation. When coating is performed on a trajectory in which the moving direction changes, such as an L-shape or a U-shape, deceleration is necessary to change the direction at a corner (direction changing portion). Further, deceleration is also required at the start or end of the operation. This is a situation that cannot be avoided as an instrument. Therefore, if a certain amount of coating is performed, the amount of coating at the corner or the start/end point increases, and the shape of the fillet 35 is disturbed.

In the underfill process, as a technique for applying a liquid material, for example, the following techniques are available.

Patent document 2 discloses a method for producing a desired coating pattern and discharging a liquid material from a nozzle while relatively moving the nozzle and a workpiece to apply a predetermined amount of the liquid material to the workpiece, the method including: a step of defining the number of times of emitting the discharge pulse or the rest pulse as a total pulse number, wherein the required discharge pulse number is defined for achieving the coating amount, and the rest is defined as a rest pulse number; measuring a discharge amount from the nozzle at a time point of the correction cycle at a preset correction cycle, and calculating a correction amount of the discharge amount; and adjusting the number of ejection pulses and the number of rest pulses based on the calculated correction amount.

Patent document 3 discloses a method for filling a liquid material discharged from a discharge device into a gap between a substrate and a workpiece placed thereon by utilizing a capillary phenomenon, the method including: a step of forming a coating pattern composed of a plurality of continuous coating regions; a step of allocating a plurality of discharge cycles, each of which is a combination of a number of discharge pulses and a number of rest pulses at a predetermined ratio, to each of the application regions; and a step of measuring a discharge amount from the discharge device at a time point of the correction cycle at a preset correction cycle and calculating a correction amount of the discharge amount, and further includes a step of adjusting the number of discharge pulses and rest pulses included in the coating pattern based on the calculated correction amount and/or a step of adjusting the length of at least one coating region and the length of the other coating region or the two coating regions connected to the coating region without changing the discharge amount per unit time in each coating region.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-344883

Patent document 2: japanese patent laid-open publication No. 2009-190012

Patent document 3: international publication No. 2010/147052 pamphlet

Disclosure of Invention

Technical problem to be solved by the invention

In patent document 1, in order to uniformly discharge droplets over the length, a step of determining the number of droplets and the interval between the droplets is required, and in this step, since the number is determined by calculating various parameters, there is a problem that a large amount of errors are generated in the calculation. Further, in order to achieve homogenization, it is necessary to make the sizes of the droplets uniform one by one, and thus there is a problem that a special mechanism is required.

In patent document 1, a maximum relative velocity for discharging uniformly over the length is determined on the premise that the relative velocity between the nozzle and the workpiece is variable. However, if the relative speed changes, the processing time changes, and the number of processes per hour is not always a problem. In addition, in the method of obtaining the maximum relative velocity and uniformly distributing the droplets in one application pattern, it is difficult to apply the droplets in accordance with the arrangement of the bumps or the corners of the chip, and there is a possibility that the droplets are distorted in a rounded shape.

Patent document 2 is an invention in which the application amount is controlled by a combination of the discharge pulse and the pause pulse, but when the ratio of the number of discharge pulses to the number of pause pulses is changed by performing correction, there is a problem that a desired pulse type does not smoothly match a pulse type assigned after correction at an end point of the application pattern. For example, when the discharge pulse is to be set at the end point of the coating pattern, if the pause pulse is set by correction, the discharge amount may vary slightly.

In patent document 3, there is a problem caused by adjusting the length of the application region in addition to the same problem caused by adjusting the number of pulses as in patent document 2. That is, since the conditions under which the coating shape changes if the length of the coating region is changed are changed, the liquid material becomes surplus or shortage, and there is a case where the round is not uniformly formed.

Therefore, an object of the present invention is to solve the above-described problems and to provide a coating method, a coating apparatus, and a program that can correct a variation in a discharge amount with high accuracy and stabilize a coating shape or a rounded shape.

Means for solving the problems

In order to solve the above problems, the inventors of the present invention have found that the length of the rest pulse is correlated with the accuracy of correction of the discharge amount in a coating method using a discharge pulse and a rest pulse.

That is, the 1 st aspect of the present invention is a liquid material coating method for filling a gap between a substrate and a work placed thereon with a liquid material discharged from a discharge device by utilizing a capillary phenomenon, the method including: a coating pattern forming step of forming a coating pattern including a plurality of continuous coating regions; a cycle allocation step of creating a plurality of cycles in which a plurality of pause pulses are combined at a predetermined ratio into one discharge pulse, and allocating the cycles to each of the application regions; a coating step of coating each coating region in the allocated cycle; a correction amount calculation step of measuring a discharge amount from the discharge device at a time point of a correction cycle at a preset correction cycle and calculating a correction amount of the discharge amount; and a discharge amount adjusting step of adjusting a ratio of the rest pulse to one discharge pulse for one or more cycles based on the correction amount calculated in the correction amount calculating step; the length of the rest pulse is set sufficiently shorter than the length of the ejection pulse.

The feature of the invention 2 is that, in the invention 1, the length of the rest pulse is not more than one twentieth of the length of the discharge pulse.

The invention according to claim 3 is the liquid crystal display device according to claim 1 or 2, wherein the discharge pulse of the same length and the pause pulse of the same length are distributed to the respective cycles in the cycle distribution step.

The feature of the invention 4 is that, in any one of the inventions 1 to 3, the lengths of the discharge pulse and the rest pulse are not changed in the discharge amount adjustment step.

The feature of the invention 5 is that, in any one of the inventions 1 to 4, the entire length of the application pattern and the length of each application region are not changed in the discharge amount adjustment step.

The feature of the invention 6 is that, in any one of the inventions 1 to 5, in the discharge amount adjusting step, the discharge amount is corrected without changing the relative movement speed of the discharge device and the workpiece.

The 7 th aspect of the present invention is the invention according to any one of the 1 st to 6 th aspects of the present invention, wherein an allowable range for determining whether or not to perform the correction is set in a step prior to the correction amount calculating step, and the correction is performed when the allowable range is exceeded.

The 8 th aspect of the present invention is the invention according to any one of the 1 st to 7 th aspects of the present invention, wherein the correction cycle is set based on time information input by a user as the correction cycle, the number of workpieces, or the number of substrates.

The feature of the invention 9 is that, in any one of the inventions 1 to 8, in the discharge amount adjusting step, the ratio of the rest pulse to one discharge pulse is adjusted for a plurality of cycles.

The 10 th aspect of the present invention is a coating apparatus including: a liquid material supply unit for supplying a liquid material; a discharge device having a discharge port for discharging the liquid material; a measuring unit that measures the amount of the liquid material discharged from the discharge port; a drive mechanism for moving the discharge port and the workpiece relative to each other; and a control unit for controlling the operations thereof; the control unit is caused to perform the coating method according to any one of the inventions 1 to 9.

The 11 th aspect of the present invention is a program for causing a control unit to execute an application method according to any one of the 1 st to 9 th aspects of the present invention in an application device including a liquid material supply unit for supplying a liquid material, a discharge unit having a discharge port for discharging the liquid material, a measurement unit for measuring an amount of the liquid material discharged from the discharge port, a drive mechanism for moving the discharge port and a workpiece relative to each other, and a control unit for controlling operations of the drive mechanism and the drive mechanism.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the relative movement speed between the discharge device and the workpiece (hereinafter, simply referred to as "relative speed") is not changed, the processing time is not changed, and the production can be performed stably and constantly. Further, the balance between the penetration into the gap of the liquid material and the supply from the discharge device is not changed, and a certain rounded shape can be formed.

Further, since a plurality of cycles can be set in one application pattern, the number of pulses included in the cycle is adjusted without changing the relative speed or the pattern length at the time of correction, and therefore, even in an uneven application pattern, the discharge amount can be kept constant. In other words, the degree of freedom is high in the production of the coating pattern, and the coating can be performed in accordance with the arrangement of the bumps or the corner portions of the chip.

Further, since the relative speed is not changed and the position of the switching cycle is not changed, the coating shape is not changed, and coating can be performed even if a coating-prohibited region or a member other than the coating target exists in the vicinity.

Further, since the adjustment is performed preferentially from the rest pulse, the influence on the discharge pulse is small, and stable discharge can be performed.

Drawings

Fig. 1 is an explanatory diagram showing an example of the coating pattern according to the present invention.

Fig. 2 is a flowchart showing a procedure of adjusting the discharge amount of the liquid material according to the present invention.

Fig. 3 is a sectional view of a main portion of the ejection type discharge device according to the embodiment.

Fig. 4 is an explanatory diagram for explaining a pulse signal to be emitted to the ejection device according to the embodiment.

Fig. 5 is a schematic perspective view of the coating apparatus according to the embodiment.

Fig. 6 is a flowchart showing a procedure of coating work in the coating apparatus according to the embodiment.

Fig. 7 is a side sectional view for explaining the underfill process.

Fig. 8 is a side sectional view for explaining the round angle.

Detailed Description

An example of an embodiment for carrying out the present invention will be described below with reference to fig. 1 and 2. Fig. 1 is an example of a coating pattern according to the present embodiment, and fig. 2 is a flowchart of a discharge amount adjustment procedure according to the present embodiment. Note that, in fig. 1, the chip 30 and the liquid material 34 are drawn with a slight space therebetween for ease of understanding. In the case of actual coating, the space is almost not partitioned, and coating is performed in the vicinity of the chip side.

The discharge device used in the present embodiment is a jet type discharge device that receives a pulse signal, drives a valve body, and causes the valve body to collide with a valve seat, thereby causing a liquid material to fly and discharge from a nozzle (a specific configuration is described in the embodiment). One of the discharge devices performs discharge by receiving one pulse signal.

The present invention can be applied to a type of discharge device that discharges in a flying manner or in a droplet state, and is not limited to the application to the ejection type.

[1] Setting of discharge amount per unit time (step 201)

The discharge amount per unit time of the liquid material discharged from the discharge device is determined. This can be determined experimentally in advance, and in this case, measurement can be performed. In any case, it is preferable to discharge and measure the liquid material actually used. This is because the discharge amount per unit time differs depending on the characteristics (viscosity, density, etc.) of each liquid material. When a plurality of discharge devices are prepared for replacement use, it is preferable to obtain the discharge amount per unit time for each discharge device because the discharge devices have a so-called individual difference. The same applies to the case where the kind of liquid material, the nozzle diameter, and the like are changed.

Further, the unevenness (variation) of the discharge amount in the same discharge device was obtained. This unevenness is sometimes considered when setting step 204 described later.

[2] Setting of necessary coating amount (step 202)

The amount of liquid material necessary to fill the gap between the substrate and the workpiece (semiconductor chip) and to form a fillet is determined. The necessary coating amount may be determined from a theoretical value based on a design drawing or the like, or may be determined by actually performing coating. However, since the theoretical value is an ideal value, it is preferable to obtain the theoretical value by actually performing coating in order to expect accuracy. The necessary coating amount can be determined as a volume or a mass. At this time, a value of the density of the liquid material used is required.

[3] Production of coating Pattern (step 203)

The edge to be coated is set in consideration of the arrangement of bumps connecting the work and the substrate, the condition of other members around the work, and the like. For example, in a rectangular workpiece, a condition is set such that coating is performed linearly along one side or L-shaped along two adjacent sides. If the coating pattern is determined, the total coating length is determined. Here, the "coating length" refers to the total length of the relative movement amount between the nozzle and the workpiece when coating is performed on one workpiece.

In consideration of the arrangement of bumps, the presence or absence of a corner portion via a chip, and the like, a plurality of coating regions having different coating amounts per unit time are set in one coating pattern, and the length of each coating region is set. For example, in fig. 1, X is set when coating is performed linearly in the direction of reference numeral 38 along one side of the workpiece 30₁～X₃In the coating region of (2), the workpiece edge is attached to the center (X)₂Area(s) is increased in coating amount to both sides (X)₁、X₃The area (b) is small. In fig. 1, for the sake of convenience of explanation, a region with a large amount of coating is drawn by a thick line, and a region with a small amount of coating is drawn by a thin line. The amount of the application is set by changing the discharge rate in step 204 described later.

[4] Setting of discharge Rate (step 204)

To achieve the purpose of]The coating amount is different for each coating area, and the coating area (X) is coated₁～X₃) The ratio (ratio) of the combined discharge pulse and pause pulse is set. Specifically, the discharge is performed for all the coating regions so that the ratio of discharge pulses (hereinafter, sometimes referred to as "discharge rate") is different for each coating region among all the pulses in one coating regionSetting the ratio. In the present embodiment, the discharge rate is defined as 100% when the entire coating region is formed of only the discharge pulse, and 0% when the entire coating region is formed of only the rest pulse. The discharge rate in one coating area is constant.

The discharge rate can be set from 100% to 0%, but in a region where the discharge amount is the largest (for example, X shown in fig. 1) in one coating pattern₂The area (b) is not 100%, and the setting may be made such that there is a margin in the upper and lower directions, for example, 80%, in consideration of the unevenness obtained in step 201 and the width of the subsequent adjustment. By doing so, it is possible to cope with both the direction of increasing the discharge amount and the direction of decreasing the discharge amount.

[5] Setting of pulse length (ON time/OFF time) (step 205)

The discharge device used in the present embodiment is of an ejection type, and therefore, by receiving one discharge pulse signal, the valve body performs one reciprocating operation and performs one discharge. The pulse signal includes a discharge pulse including an on time, which is a time when the valve element is separated from the valve seat, and an off time, which is a time when the valve element is in contact with the valve seat, and a rest pulse, which is configured only by the off time without setting the on time and does not perform a discharge operation. The ejection pulse and the rest pulse are emitted at a constant frequency (the ejection pulse and the rest pulse have different frequencies).

The on-time and off-time of the discharge pulse and the rest pulse are set for each coating region. However, there is an appropriate range for the on time and the off time of the discharge pulse, and if the on time and the off time deviate from this range, a problem occurs (the liquid material excessively adheres to the nozzle tip, a droplet as a result of application is divided into a plurality of droplets and scatters, the liquid material is not ejected, or the like). The appropriate range varies depending on the characteristics of the liquid material, the discharge amount, and the like, but for example, the on time may be set within a range of 2 to 10[ msec ], and the off time may be set within a range of 2 to 10[ msec ]. Also, an on time of 3 msec and an off time of 3 msec are most commonly used. The on-time and the off-time are in principle the same value. On the other hand, the rest pulse does not have such a time range.

The coating pattern is composed of a combination of a plurality of cycles. Here, the "cycle" refers to a combination of one discharge pulse and one pause pulse. As described above, since the coating amount is different in each coating region, the cycle performed in each coating region is different. That is, the ratio of the discharge pulse and the rest pulse to be combined is made different in each coating region. On the other hand, the pulse length (pulse period, time obtained by summing the on time and off time of the pulse) is not different for each coating region. In other words, the pulse length does not change in one coating pattern. The pulse length does not need to be changed if it is set once in the same discharge device as long as the type of the liquid material is not changed or the type of the work to be coated is not changed.

In the present invention, the pause pulse length is set to be shorter than the discharge pulse length, preferably one twentieth or less, more preferably one hundredth or less, and further preferably one thousandth or less. This is because, as described later, the adjustment can be made finer by shortening the rest pulse length that is increased or decreased with priority. If the rest pulse length is one-hundredth of the discharge pulse length, the discharge rate can be controlled to about 1% (order), and if it is one-thousand, the discharge rate can be controlled to about 0.1%.

[6] Setting of moving speed (step 206)

There are two determination methods for setting the relative movement speed V between the discharge device and the workpiece. One is a method of determining and setting a target moving speed V from a target production amount or the like. Since the speed is not substantially changed during the start of the coating operation, the mass production of products, or the like, the moving speed V can be freely determined. Of course, even if it is free, the moving speed of the machine is determined within the range because the machine has a limited moving speed.

The other is a method of calculating the moving speed V from the respective set values. Taking FIG. 1 as an example, the discharge amount per unit time is defined as A g/sec]The necessary coating amount is G₀[g]Making the length of the coating region X [ mm ]]At a moving speed V [ mm/sec ]]As described below.

[ formula 1]

If there is a change in the respective setting values on the right side of equation 1, the moving speed V is calculated and modified each time.

[7] Pulse number calculation (step 207)

The number of discharge pulses and rest pulses in each coating region is set based on the discharge rate in each coating region set by step 204 described above. In the present embodiment, the number of pause pulses for one discharge pulse is calculated as a basic cycle.

First, the length of one discharge pulse (the total time of the on time and the off time) is D, the length of one rest pulse (the total time of the on time and the off time) is S, and the number of discharge pulses in each coating region is n_iThe number of rest pulses in each coating region is defined as m_i. As described above, the discharge rate is the ratio of the discharge pulses to the total number of pulses in one coating region, and therefore, the discharge rate C is_iAs shown in the following formula.

[ formula 2]

Here, the subscript i indicates the number of the coating region, and for example, in fig. 1, i is any one of 1, 2, and 3.

Number m of rest pulses for each coating region from the above formula_iAs shown in the following formula.

[ formula 3]

Thus, the number of discharge pulses is set to 1 (i.e., n)_iNumber m of rest pulses for each coating region at time of = 1)_iThe following formula is shown below.

[ formula 4]

In a specific example, when the on time of the discharge pulse is set to 3[ msec ], the off time is set to 3[ msec ], the on time of the rest pulse is set to 0.005[ msec ], the off time is set to 0.005[ msec ], and the discharge rate is set to 80%, the number m of rest pulses per one discharge pulse is 150 in equation 4. When the discharge rate is set to 40% by the same discharge pulse length and pause pulse length, the number m of pause pulses per one discharge pulse is 900. In this specific example, the calculation result is the assigned numerical value (natural number), but in the case of no assignment, the numerical value is rounded to a natural number, for example.

A pause pulse for one discharge pulse is calculated for each coating region, and the combination of the pause pulse and one discharge pulse is used as a basic cycle. In an actual coating operation, the basic cycle is relatively moved in the coating region, and the time or distance is repeated until the time or distance reaches a set value. Taking FIG. 1 as an example, the discharge device is moved from the application area X₁Starts moving until the coating area X₁And a coating region X₂The connection point (1) repeats the 1 st basic cycle and discharges the liquid. At the arrival at the coating region X₁And a coating region X₂After the connection point (2), the discharge device is switched to the 2 nd basic cycle without stopping. Then, until the coating region X₂And a coating region X₃The connection point (2) repeats the 2 nd basic cycle and discharges. Similarly, in reaching the coating region X₂And a coating region X₃After the connection point (3), the discharge is continued by switching to the 3 rd basic cycle. Then, the coating device reaches the coating region X₃And then stops at the right end, and the coating operation is ended. The number of application regions in the application pattern can be increased or decreased, or the application pattern can include corners or the like.

[8] Setting of correction period (step 208)

A correction cycle is set as a cycle for correcting the discharge amount. As the correction cycle, for example, time information input by a user, the number of chips or substrates, and the like are set. When the predetermined time is set, the time at which the change in the discharge amount of the liquid material is expected to exceed the allowable range from the start of the operation is set. When the number of pieces is set, the number of pieces to be processed is determined and set from the time of processing one chip or the time of processing one substrate (the time of carrying in → coating → carrying out), and the predetermined time.

When the correction period is set, it is preferable to calculate the relationship between the coating pattern and the necessary coating amount and the like for the liquid material to be applied by a predetermined experiment and reflect these values in the correction period. By setting these parameters, even when there is an influence due to a viscosity change of the liquid material caused by a temperature change, clogging of the discharge portion, and a head difference, a change in the discharge amount can be coped with.

As the limit value of the use time of the liquid material, a value calculated based on a service life (potlife) specified by a manufacturer may be stored in advance and incorporated into the correction cycle.

When setting the correction period, it is necessary to consider a change in viscosity of the liquid material due to a change in time or temperature, but the following description is made on the premise that only a change in viscosity occurs with the passage of time.

It is needless to say that a known technique for controlling the viscosity of the liquid material by adjusting the temperature of the discharge portion can be applied to the present invention.

[9] Implementation of the correction

A correction amount corresponding to a change in the discharge amount due to a change in the viscosity of the liquid material is calculated at a set correction period.

As a method of calculating the correction amount, there are (a) a method of measuring the weight at the time of discharge for a certain period of time and calculating the correction amount based on the difference from the necessary importance, and (B) a method of measuring the discharge time required until the discharge becomes the necessary importance and calculating the correction amount based on the difference from the previous discharge time. In the present invention, any method can be applied, but a specific calculation procedure of the correction amount will be described below based on the method (a).

(i) Discharge amount measurement (step 209)

The nozzle (i.e., the discharge device) is moved above the scale to discharge the liquid material at a fixed position. The discharge to the scale is continuously performed for a predetermined period of time. The fixed time may be, for example, a time required to discharge the set coating pattern, a time required for the test or measurement performed in step 201, or the like.

Then, the weight G of the liquid material discharged to the scale is read₁. From the measured weight G₁And necessary weight G₀The rate of change R is calculated. The rate of change R is represented by the following formula.

[ formula 5]

When the change rate R is negative, the discharge amount in a certain discharge time is less than the necessary weight, and therefore, the correction amount is calculated so that the discharge amount increases in step 210 described below. On the other hand, when the change rate R is positive, the discharge amount in a certain discharge time is larger than the necessary weight, and therefore, the correction amount is calculated so that the discharge amount decreases in step 210 described below.

The weight measurement may be performed a plurality of times to obtain an average value. By doing so, the measurement value can be obtained with higher accuracy.

(ii) Correction amount (New number of pulses) is calculated (step 210)

When the correction amount is calculated, a new discharge rate is calculated from the change rate in step 209, and a new pulse number is calculated based on the calculation formula in step 207.

First, the discharge rate is determined from the new discharge rate. When the change rate R is negative as described above, the correction amount must be calculated so that the discharge amount increases. That is, if the new discharge rate of each region is set to C_i ^'The formula is as follows.

[ formula 6]

The subscript i denotes the number of the coating region, and in fig. 1, i is any one of 1, 2, and 3 (the same applies to the following formula). On the other hand, when the change rate R is positive, the correction amount must be calculated so that the discharge amount decreases, and therefore, the new discharge rate for each region is expressed by the following formula.

[ formula 7]

Next, a new number of pulses is calculated for each of the application regions based on the new discharge rate for each region obtained by the above equation 6 or 7 and the above equation 4 shown in step 207.

Specifically, illustration is made. Here, the same numerical values as those in step 207 described above are considered. New discharge rate C in the region where the initial set discharge rate is 80%_i ^'If the discharge amount measured after a certain correction cycle is less than 10% of the necessary discharge amount (if the rate of change R is minus 10%), the discharge amount becomes 88% according to equation 6. Therefore, the number of pause pulses per one discharge pulse is 82 according to equation 4. Further, a new discharge rate C in a region where the initial set discharge rate is 40%_i ^'The value was 44% according to equation 6. Therefore, the number of pause pulses per one ejection pulse is 764 according to equation 4. The new pulse numbers thus obtained are combined and set as a new cycle in the application pattern.

In this way, in each application region, the number of pause pulses per one discharge pulse is increased, thereby enabling finer adjustment.

(iii) Correction is carried out (step 211)

When it is determined in step 209 that the correction of the discharge amount is necessary, the new discharge rate calculated in step 210 is C_i ^'The new number of pulses is calculated and corrected by resetting all the coating regions of the coating pattern.

Here, the judgment of whether or not the discharge amount correction is required is not always performed when the weight difference or the change rate is 0 but is not present, but it is preferable to perform the correction only when the difference or the change rate R of the measured discharge amount (measurement value) exceeds an allowable range (for example, ± 5%). A preferred mode of setting the correction of the allowable range is described in detail in, for example, japanese patent No. 3877038 to which the present applicant is directed. That is, an allowable range for determining whether or not to perform correction is set, and correction is performed only when the difference value or the change rate exceeds the allowable range.

The steps 209 to 211 are executed in the correction cycle set in step 208, or when the type (size or shape) of the substrate is changed, so that an optimum amount of coating can be always achieved regardless of the change in viscosity of the liquid material with time.

According to the present invention described above, since the relative speed is not changed, the processing time is not changed, and the production can be stably performed with certainty. Further, the liquid material can be formed into a predetermined rounded shape without changing the balance between the penetration into the gap and the supply from the discharge device.

In addition, since a plurality of cycles can be set in one application pattern, and the number of pulses included in the cycle can be adjusted without changing the relative speed or the pattern length at the time of correction, the application amount can be kept constant even in an application pattern in which the application amount is not uniform. In other words, the degree of freedom is high in the production of the coating pattern, and the coating can be performed in accordance with the arrangement of the bumps or the corners of the chip.

Further, since the relative speed is not changed and the position of the switching cycle (i.e., the length of each application region) is not changed, the application shape is not changed, and even if a member other than the application-inhibited region exists in the vicinity, the coating can be performed.

In the present invention, the number of pause pulses is varied greatly by the correction, but the variation in the number of discharge pulses is small, and therefore stable discharge can be performed.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples at all.

Examples

[ spitting device ]

As shown in fig. 3, the discharge device 1 of the present embodiment is a jet type discharge device including a piston 2 as a valve provided in a vertically movable manner, a storage container 3 pressurized by compressed air whose pressure is adjusted by a control unit 11, and a nozzle 4 communicating with the storage container 3. Further, a switching valve 6 for supplying and exhausting the working gas for moving the piston 2 upward through the control unit 11 and a spring 7 for biasing the piston 2 downward are provided. Further, a stroke adjusting member 8 for adjusting the amount of movement of the piston 2 is provided above the spring 7. A heater 9 for heating the nozzle 4 and the liquid material 34 located therein is provided in the vicinity of the nozzle 4. The temperature sensor 10 is provided in the vicinity of the nozzle 4 so as to face the heater 9, and is used when performing control for maintaining the nozzle 4 and the liquid material 34 located therein at a predetermined temperature.

The liquid material 34 filled in the storage container 3 is discharged in the form of droplets from the nozzle 4 by operating the switching valve 6 in response to the pulse signal emitted from the control unit 11, and moving the piston 2 up and down. The liquid material 34 discharged from the nozzle 4 is applied in a dot shape to the substrate 29 positioned below the nozzle 4 by relatively moving the discharge device 1 and the substrate 29.

More specifically, the discharge device 1 operates as follows. The pulse signal applied to the discharge device 1 is, for example, as shown in fig. 4. When the pulse signal is on, as indicated by reference numeral 14, gas is supplied by the operation of the switching valve 6, and the piston 2 is raised to open the nozzle inlet 5. When the pulse signal is turned off, the switching valve 6 is operated to discharge the gas, and the piston 2 is lowered by the repulsive force of the spring 7 to close the nozzle inlet 5. That is, one discharge pulse 14 is one unit of on for raising the piston 2 (opening the nozzle inlet 5) and off for lowering the piston 2 (closing the nozzle inlet 5), and one drop of the liquid material 34 is discharged in the one unit of operation. In fig. 4, D is the length of the discharge pulse 14. On the other hand, as indicated by the symbol 15, the piston 2 is made inoperative while the off state of the pulse signal continues, and the nozzle inlet 5 is closed between one unit (i.e., time unit of S) with respect to one rest pulse 15. In fig. 4, S is the length of the rest pulse 15.

When coating is performed along the side of the workpiece 30, the control unit 11 emits pulse signals (reference numerals 14 and 15) preset for the discharge device 1 while moving the nozzle 4 simultaneously with the start of coating, and continuously discharges the liquid material 34. The liquid material 34 discharged along one side of the workpiece 30 is filled in the gap between the workpiece 30 and the substrate 29 by capillary action.

[ coating apparatus ]

As shown in fig. 5, the coating device 16 of the present embodiment includes a discharge device 1, an XYZ drive mechanism 17, a transport mechanism 18, a coating stage 19, an adjustment substrate 20, an adjustment stage 21 on which the adjustment substrate is placed, a scale 22, detection devices (a contact sensor 23, a laser displacement meter 24, and a camera 25), and a control unit 11.

The discharge device 1 is the above-described ejection type discharge device, and discharges the liquid material 34 upon receiving pulse signals (reference numerals 14 and 15) from the control unit 11.

The XYZ drive mechanism 17 is provided with the discharge device 1, and a laser displacement meter 24 and a camera 25 which are part of a detection device described later, and can move the discharge device 1, the laser displacement meter 24, and the camera 25 in XYZ directions indicated by reference numeral 26. That is, the discharge device 1 can be moved above the substrate according to the application pattern set in the control unit 11, and the discharge device 1, the laser displacement meter 24, and the camera 25 can be moved up to the scale 22 or a device such as the contact sensor 23 which is a part of the detection device described later fixed at another position, or the adjustment table 21 on which the adjustment substrate 20 described later is placed.

The conveying mechanism 18 carries in a substrate 29 on which a workpiece 30 before coating operation is placed from a direction indicated by reference numeral 27 outside the apparatus, and conveys the substrate to the vicinity of the discharge apparatus 1 where coating operation is performed. Then, the substrate 29 on which the coating operation is completed is carried out in a direction indicated by reference numeral 28 outside the apparatus.

The coating stage 19 is provided between the conveying mechanisms 18 at substantially the center of the conveying mechanisms 18. When the coating operation is performed, the substrate 29 is lifted to be fixed. When the substrate 29 is transferred, it is lowered without interfering with the transfer.

The adjustment table 21 is provided in the vicinity of the conveyance mechanism 18. A bare substrate, that is, a substrate on which components and the like are not mounted or a substrate on which a dummy workpiece is mounted (these are collectively referred to as the adjustment substrate 20) is placed, and is used for performing an operation associated with an adjustment operation of the discharge amount of the liquid material 34.

The scale 22 is provided in the vicinity of the conveyance mechanism 18 for measuring the weight of the liquid material 34 discharged by the discharge device 1. The measurement result obtained by the scale 22 is transmitted to the control unit 11.

The detection device includes a contact sensor 23 as a sensor for detecting the height position of the nozzle 4, a laser displacement meter 24 as a sensor for detecting the height position of the substrate 29, and a camera 25 for detecting the position of the workpiece 30. The laser displacement meter 24 and the camera 25 are provided in the XYZ drive mechanism 17 together with the discharge device 1, and are movable in the XYZ direction (reference numeral 26). The contact sensor 23 is fixed to the adjustment table 21.

The control unit 11 includes an overall control unit that controls the overall operation of the coating device 16 and a discharge control unit that controls the operation of the discharge device 1.

[ coating operation ]

Next, a series of coating operations using the coating device 16 will be described. Fig. 6 shows a flowchart thereof.

In addition to the parameters (on/off time or the ratio of the combination) regarding the nozzle described above, the discharge amount changing factors (nozzle diameter, stroke amount, applied pressure, and the like) of the discharge device 1 are adjusted, and conditions for stably performing discharge are searched and set (step 601). This operation can be performed while measuring the weight, diameter, and the like as a result of actually applying the liquid material 34. In this case, it is also preferable to confirm whether or not the liquid material 34 is not excessively attached to the tip of the nozzle 4, whether or not the liquid droplets as a result of the application are divided into a plurality of droplets and scattered, and the like.

Next, the discharge amount correction step described in the above embodiment is performed (see steps 209 to 211) (step 602). The discharge amount correction step can be performed not only when the correction cycle is reached but also in the preparation stage. After the correction process is completed, test coating is performed using a bare substrate or a dummy substrate before the start of the present coating, and final confirmation is performed (step 603). The test coating is preferably applied using a substrate on which actual components and the like are mounted. Final confirmation is performed, and if it is not a defect, the conditions of step 601 are reconsidered, and if it is not a defect, the present coating operation is started (step 604).

When the coating operation is started, the substrate 29 is first carried in and carried to the vicinity of the discharge device 1, and then fixed to the coating table 19 (step 605). Then, image recognition by the camera 25 is performed with respect to the substrate 29 on the coating table 19, and alignment is performed to perform positioning (step 606). An image serving as a reference for alignment is stored in the control unit 11 in advance. After the positioning is finished, coating is performed (step 607). The substrate 29 on which the coating is completed is carried out of the coating apparatus 16 (step 608).

At the time point when the substrate 29 on which the coating is finished is carried out of the apparatus 16, it is determined whether or not a preset correction cycle (the number of workpieces or the number of substrates) has been reached (step 609). When the correction cycle is reached, the process proceeds to the correction step as the next step, and when the correction cycle is not reached, the process proceeds to step 611.

In the correction step, the discharge device 1 is moved onto the scale 22, and the weight is measured by discharging. If the measured result exceeds the allowable range, the discharge amount correction process described in the above embodiment is performed (steps 209 to 211) (step 610). In contrast, in the case where the allowable range is not exceeded, the process proceeds to step 611. After the correction process is completed, or the substrate 29 is carried out and immediately thereafter, it is determined whether or not there is a substrate 29 that should be coated but not coated (step 611). When there is an uncoated substrate 29, the process returns to step 605 to carry in the substrate 29 again and perform the coating operation. If there is no uncoated substrate 29, the coating operation is ended.

The above is a basic series of flows from the preparation stage to the present coating operation. The present invention is not limited to this flow, and various modifications can be made within the scope of the technical idea of the present invention.

[ formula for calculating pulse number ]

In the above-described embodiment, the number of pause pulses for one discharge pulse is calculated, and then the combination is set for each coating region as a basic cycle. However, in the present embodiment, the number of discharge pulses and the number of stop pulses are calculated so as to achieve a desired coating rate over the length of the coating region, and coating is performed. Specifically, as described below.

First, the length of one discharge pulse (the total time of the on time and the off time) is D, the length of one pause pulse (the total time of the on time and the off time) is S, and the number of discharge pulses in each region is n_iThe number of rest pulses in each region is defined as m_i. Further, the relative speed of the discharge device and the workpiece is denoted by V, and the discharge rate of each application region is denoted by C_iThe length of each coated region is defined as X_i. The subscript i indicates the number of the coating region, and in fig. 1, i is any one of 1, 2, and 3.

If the time is taken as a reference, the ratio of the discharge pulse in the time required for the discharge device to pass through a certain coating region is the discharge rate, and therefore the following expression is established.

[ formula 8]

The number n of discharge pulses in each coating region is determined according to the formula_iCan be calculated as follows.

[ formula 9]

On the other hand, the portion of the discharge device that is not occupied by the discharge pulse is the proportion occupied by the rest pulse in the time required for the discharge device to pass through a certain coating region, and therefore the following equation holds.

[ formula 10]

The number m of rest pulses for each coating region according to this formula_iCan be calculated as follows.

[ formula 11]

Using the above equations 9 and 11, the number of discharge pulses and rest pulses in each coating region was calculated. Then, it was set to the coating pattern.

Specific examples are given for explanation. Considering the coating pattern as in FIG. 1, the length D of one discharge pulse is set to 6[ msec [ ]]One rest pulse is made to have a length S of 0.01[ msec [. ]]The moving speed V is 50[ mm/s ]]So that the coating region X₁And X₃Has a length of 5[ mm ]]The discharge rate is set to 40%, and the application region X is set to₂Has a length of 10[ mm ]]The discharge rate was adjusted to 80%.

Coating region X₁And X₃The number of discharge pulses of (3) is 7 according to equation 9, and the coating region X₁And X₃The number of rest pulses of (a) is 6000 according to equation 11. On the other hand, coating region X₂The number of discharge pulses of (3) is 27 according to equation 9, and the coating region X₂The number of rest pulses of (2) is 4000 according to equation 11.

The number of pulses thus obtained is distributed over the length of each application region and set in the application pattern.

Industrial applicability

The present invention can be applied to coating using a type of discharge device in which a discharged liquid material is separated from a nozzle before coming into contact with an object to be coated. Examples of the discharge device include a jet type in which a valve body collides with a valve seat to eject a liquid material from a nozzle tip in a flying manner, a plunger type in which a plunger is moved and then rapidly appears to eject the liquid material in a flying manner from a nozzle tip, a continuous jet type, and an on-demand (on-demand) type ink jet type. It is needless to say that the present invention can be applied to the underfill process of the semiconductor package.

Description of the symbols

1: the discharge device 2: and (3) a piston: storage container 4: nozzle 5: nozzle inlet 6: a switching valve 7: and (4) a spring 8: stroke adjusting member 9: heater 10: temperature sensor 11: the control unit 12: gas piping 13: the harness 14: ejection pulse 15: rest pulse 16: the coating device 17: XYZ drive mechanism 18: conveyance mechanism 19: coating table 20: adjustment substrate 21: adjustment table 22: scale 23: the contact sensor 24: laser displacement meter 25: the camera 26: moving direction 27: carry-in direction 28: carrying-out direction 29: substrate 30: workpiece (semiconductor chip) 31: protruding electrode (bump) 32: electrode pad 33: connection portion 34: resin, liquid material 35: round corner portion, round corner 36: fillet width 37: fillet height 38: the coating direction.

Claims (11)

1. A method for coating a liquid material, characterized in that,

the method is a liquid material coating method for filling a gap between a substrate and a work placed thereon with a liquid material discharged from a discharge device by utilizing a capillary phenomenon,

the method comprises the following steps:

a coating pattern forming step of forming a coating pattern including a plurality of continuous coating regions;

a cycle allocation step of creating a plurality of cycles in which a plurality of pause pulses are combined at a predetermined ratio into one discharge pulse, and allocating the cycles to each application region;

a coating step of coating each coating region in the allocated cycle;

a correction amount calculation step of measuring a discharge amount from the discharge device at a time point of a correction cycle at a preset correction cycle and calculating a correction amount of the discharge amount; and

a discharge amount adjusting step of adjusting a ratio of the rest pulse to one discharge pulse for one or more cycles based on the correction amount calculated in the correction amount calculating step,

the length of the rest pulse is set to be sufficiently shorter than the length of the ejection pulse,

the discharge pulse is composed of an on time and an off time, the rest pulse is composed of only an off time,

the length of the rest pulse is less than one twentieth of the length of the discharge pulse.

2. A method of coating a liquid material according to claim 1,

in the cycle allocation step, the discharge pulses having the same length and the rest pulses having the same length are allocated to each cycle.

3. A method of coating a liquid material according to claim 1 or 2,

in the discharge amount adjusting step, the lengths of the discharge pulse and the rest pulse are not changed.

4. A method of coating a liquid material according to claim 1 or 2,

in the discharge amount adjusting step, the entire length of the application pattern and the length of each application region are not changed.

5. A method of coating a liquid material according to claim 1 or 2,

in the discharge amount adjusting step, the discharge amount is corrected without changing the relative movement speed of the discharge device and the workpiece.

6. A method of coating a liquid material according to claim 1 or 2,

in a step prior to the correction amount calculating step, an allowable range for determining whether or not to perform correction is set, and when the allowable range is exceeded, correction is performed.

7. A method of coating a liquid material according to claim 1 or 2,

the correction cycle is set based on time information input by a user as a correction cycle, the number of workpieces, or the number of substrates.

8. A method of coating a liquid material according to claim 1 or 2,

in the discharge amount adjusting step, the ratio of the rest pulse to one discharge pulse is adjusted for a plurality of cycles.

9. A method of coating a liquid material according to claim 1 or 2,

the ejection pulse and the rest pulse have different frequencies.

10. A coating device is characterized in that a coating device is provided,

the disclosed device is provided with:

a liquid material supply unit for supplying a liquid material;

a discharge device having a discharge port for discharging the liquid material;

a measuring unit that measures the amount of the liquid material discharged from the discharge port;

a drive mechanism for moving the discharge port and the workpiece relative to each other; and

a control part for controlling the actions of the above-mentioned components,

causing a control section to perform the coating method according to claim 1 or 2.

11. A coating device is characterized in that a coating device is provided,

the disclosed device is provided with:

a liquid material supply unit for supplying a liquid material;

a discharge device having a discharge port for discharging the liquid material;

a measuring unit that measures the amount of the liquid material discharged from the discharge port;

a drive mechanism for moving the discharge port and the workpiece relative to each other; and

a control part for controlling the actions of the above-mentioned components,

the coating method according to claim 9 is performed by a control unit.