CN1013409B - Leak detection and screening test for packaged details - Google Patents

Leak detection and screening test for packaged details


Publication number
CN1013409B CN 87106017 CN87106017A CN1013409B CN 1013409 B CN1013409 B CN 1013409B CN 87106017 CN87106017 CN 87106017 CN 87106017 A CN87106017 A CN 87106017A CN 1013409 B CN1013409 B CN 1013409B
Prior art keywords
small opening
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Application number
CN 87106017
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Chinese (zh)
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CN87106017A (en
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Application filed by 哈尔滨工业大学 filed Critical 哈尔滨工业大学
Priority to CN 87106017 priority Critical patent/CN1013409B/en
Publication of CN87106017A publication Critical patent/CN87106017A/en
Publication of CN1013409B publication Critical patent/CN1013409B/en



A cavity which can be filled with gas is composed of detected components and a leakage detection system. Then, the cavity is submerged in testing liquid (ethanol or water), and is filled with gas (air, nitrogen, etc.) whose pressure intensity is PG. When PG is greater than the critical pressure intensity Pgamma0 of bubbles generated in a leakage hole, the leakage hole can be detected out from the bubbles in the leakage hole. The motion law by which the gas passes through the leakage hole is analyzed by a mixed flow model of the gas so that the relationship between leakage detection sensitivity R*1(the product of a leakage rate and the length of the leakage hole) and the pressure intensity PG by a bubble method with the model. The present invention can be used for the quantitative detection and the qualitative screening of the sealing performance of electronic components and the components of other devices with sealing requirements.


The invention belongs to electronic device manufacturing technology.
Have the parts method for conducting leak test of the device (comprising electronic devices and components) of sealing requirements to mainly contain following several:
1. helium mass spectrum leak detection method: utilize the helium mass spectrometer leak detector leak detection.Tested parts press seal on the pipeline of vacuum system, then is sprayed onto helium on the parts by tubule, and parts are if any small opening, and helium enters in the leak locator by small opening and is detected.It can the quantitative test leak rate, and remolding sensitivity is higher, and highly sensitive leak locator can detect 10 -9~10 -10Handkerchief rice 3The small opening of/second leak rate.This method shortcoming is the equipment complexity, and installation cost and test fee are higher, the more important thing is and can not determine the small opening position intuitively and accurately.
2. halogen leak detection: utilize halogen leak detector, make the gas that contains halogen can only flow out the ionization chamber internal ionization that (or inflow) enter into leak locator again, produce electric current, detect small opening by the parts small opening.But this method quantitative measurement leak hole leak rate, but remolding sensitivity is lower.Generally can detect 10 -7Handkerchief rice 3/ second leak rate.Determine that accurately the small opening position is very difficult; Relatively important disadvantages is, as meets the high concentration halogen, and instrument can be malfunctioning suddenly; Often want " cleaning " ionization chamber and check sensitivity, use comparatively trouble, testing expenses are also higher.
3. fluorometric method: tested parts are put in the muddy liquid of phosphor powder, then are put in the vacuum chamber and take out low vacuum, make phosphor powder penetrate in the small opening of parts in company with liquid; Use the UV-irradiation parts after the drying again, owing to there being phosphor powder to send fluorescent in the small opening, thereby detect small opening.This method troublesome poeration not only can not detection by quantitative, and sensitivity is not high; Even more serious is is easy to take place flase drop (because locating also can leave phosphor powder in the pit or the slit of not leaking etc.).
4. decoration method: tested parts are put in the liquid that contains pigment (generally adopting poinsettia), then be put in the vacuum chamber and take out low vacuum, the liquid that has dyestuff is penetrated in the small opening of parts, observe after the oven dry, having the dyeing place often to be judged to is small opening.Though this method is simple, be that leak detection sensitivity is low equally, leak rate that can not the quantitative measurement small opening; Equally also be easy to take place the problem (pit is arranged, and the slit is stain grade and all may be colored) of flase drop.
Above-mentioned each method is concerning the parts small opening of the electronic devices and components produced in enormous quantities detects, because equipment is complicated or leak detection sensitivity is not high former thereby all inapplicable.
Purpose of the present invention just provide a kind of can to the encapsulation parts carry out highly sensitive quantitatively and the method for qualitative detection have high leakproofness so that assurance is used for the parts of highly reliable electronic devices and components, thereby guarantee its long term operation stability and reliability; Can also provide the foundation of improving the parts manufacturing process for parts manufacturing firm.
Task of the present invention is: the first, propose and implement a kind of energy quantitatively and the method for qualitative detection parts sealing quality; The second, its sensitivity will be higher than other method commonly used at present, satisfies the requirement of highly reliable product to the parts sealing; The 3rd, this method is used convenient, and equipment and leak detection expense are low, easy to utilize; The 4th, can accurately point out the small opening position, be convenient to improve the parts manufacturing process.
The present invention is that the parts small opening that the ultimate principle with bubble method detection is applied to electronic devices and components or other midget plant detects.At first utilize tested parts and leakage detection apparatus to constitute the cavity that can inflate, it is dark to cover 1~2 centimetre of tested parts with test(ing) liquid again; Fill gas with certain air pressure with the pipeline of gas cylinder by leakage detection apparatus to cavity, when parts had small opening, gas flowed out by small opening and produces bubble, thereby detects small opening intuitively and accurately; Can quantitatively measure the leak rate of small opening according to the gas pressure intensity in the cavity and parts small opening structure.
Because the gas pressure intensity that charges into to cavity in this method can reach higher numerical value,, be easy to detect 10 so leak detection sensitivity is very high -11Handkerchief rice 3The leak rate of/second, every in other words leak rate can both detect greater than the small opening of this value.That detects is highly sensitive, leak rate numerical range wide (comprising thick leakage and thin the leakage), small opening change in radius scope is big, when detecting utmost point less leakage rate, the free path of leak rate radius and gas molecule is close on the order of magnitude, when analytical gas passes through the characteristics of motion of small opening so in theory, should be different from other leak detecting and only adopt molecular flow model or viscous flow model, and must adopt mixed flow model.In mixed flow model, molecular flow and viscous flow exist simultaneously, suppose that the small opening that we detect is that a radius is r 0, small opening length is the cylindrical microtubule of l, the leak rate of this kind small opening is:
R=R L+R m<1>
R LBe the leak rate of viscous flow motion decision, its expression is:
η is the viscous system of air, P d=1 * 10 5Handkerchief; And R MBe the leak rate of molecular flow motion decision, its expression is:
A is a gas law constant, and T is gas temperature (K), and M is the air molecule amount, P d=1 * 10 5Handkerchief.
Radius is r 0Cylindrical small opening, in test(ing) liquid, produce the required critical pressure of bubble and be:
P aBe liquid top atmospheric pressure, α is the surface tension coefficient of test(ing) liquid, P LBe the additional pressure that test(ing) liquid weight produces bubble, it is compared and can ignore with preceding two.Gas pressure intensity P in cavity GSatisfy:
During condition, just can produce bubble from small opening.N is the number of bubbles that produces, P RcAnd V RoBe respectively that radius is r cBubble in gas pressure intensity and bubble volume.
Solve r from (4) formula o, and ignore P LValue, substitution (2) and (3) formula, result's substitution again (1) formula draws the critical pressure P that produces bubble RoAnd close between the leak rate R that desire detects and small opening length l product R * l and be:
When we inflate pressure P to cavity G≈ P RoThe time, (6) formula can be expressed as:
Fig. 1 provides the P of two kinds of test(ing) liquids (second alcohol and water) Ro(P RG) and leak detection sensitivity R * l between relation.This result shows, when cavity fills just can produce the pressure P of a spot of bubble GMeasure by tensimeter) time, by (7) formula, or can determine the R * l value of small opening from Fig. 1, by the position of small opening, determine the small opening length l approx again, just obtain or measured leak rate at last.
Gas flows out the formation bubble by small opening needs certain hour, it and (P G-P Ro) big or small relevant with R * l value.Under mixed flow model, calculate the time △ t that forms a bubble approx, for the sensitivity R * l=R that hunts leak L* l+R M* l combines, and represents with △ t/l:
△ t l = 4 π r 2 c p 2 d 3(R M × l 1 d +2P G R L × l ) 1n
(R M × lP d + R L × l (P G + P ro ) ( P G - P r c ) 〔 R M + lP d + R L × l (P G + P r c ) 〕(P G - P r c )
To two kinds of test(ing) liquids of second alcohol and water, be parameter with R * l, △ t/l and P G-P RoRelation is shown in Fig. 2.Utilize the result of this figure, just can determine under a certain leak detection sensitivity R * l, allow P G-P Ro<<10 5Handkerchief (is P G≈ P Ro) time △ t/l value that should choose; Estimate by the position of small opening on the parts and the small opening length l, thereby just determine △ t value.Here it is for detecting a certain length is that its leak rate of l is the small opening of R, the pressure P of cavity inflation G≈ P Ro(corresponding with R * l value) waits for that observing the △ t time just can find from the bubble of small opening generation.
The sealing that the product component of sealing requirements is arranged is the basis that guarantees its product hermeticity, never has a kind of method of easy, high Precision Detection small opening in the past.The present invention can carry out wide region, detection by quantitative and qualitative screening in high sensitivity to the leak rate of parts, can accurately point out the small opening position again.This method helps parts manufacturing plant and improves parts manufacturing process and quality control; For finished product manufacturing plant provides sealing qualified parts, avoid product to cause the defective and economic loss of product because of the parts sealing is defective, improve product reliability, have important economic benefit and social benefit.
The present invention can be applicable to electronic devices and components (semiconductor devices, sealed relay, hermetically sealed connector etc.), and has the parts sealing of seal request and other device to carry out detection by quantitative and qualitative screening.
The key technical indexes of the present invention: detection sensitivity (R * l) relevant with the surface tension system of test(ing) liquid, when being test(ing) liquid with ethanol:
Sensitivity is not less than: 1 * 10 -14Handkerchief rice 4/ second (or 1 * 10 -11Atmospheric pressure centimetre 4/ second).When being test(ing) liquid with water:
Sensitivity is not less than: 5 * 10 -13Handkerchief rice 4/ second (or 5 * 10 -10Atmospheric pressure centimetre 4/ second).
Fig. 1 is for producing bubble critical pressure P Ro(≈ P G) and detectable R * l between concern synoptic diagram; Fig. 2 is wait △ t/l observing time and (P G-P Ro) concern synoptic diagram; Fig. 3 is a parts small opening monitor station synoptic diagram, 1 spanner among the figure, and 2 housing screws, 3 cross bars, 4 straight pins, 5 pressure heads, 6 vertical rods, 7 organic glass covers, 8 tested shells, 9 seal gaskets, 10 pedestals, 11 bases, 12 send leakage fluid dram, 13 fill, relief port 14 test(ing) liquids.
Use simple test of the present invention as shown in Figure 3.Here be that the small opening that encapsulates on the pipe cap glass insulator with detection or screening power transistor G type is an example, pipe cap (8) is placed on the seal gasket (9), there is the side pressure head (5) of viewport to be enclosed within on the pipe cap again, the cross bar (3) that has housing screw (2) and spanner (1) is put down, and give locking; Pull spanner (1) screw (2) is descended, be pressed on the pressure head (5), add certain pressure, pipe cap is sealed with glue heat (9) and pedestal (10), at this moment pipe cap and pedestal have formed a cavity V; By air-filled pore (13), to fill in the cavity with the controlled gas of pressure (pressurized air, nitrogen, oxygen all can), pressure values is by the electromagnetic valve control that is in series with gas-filled tube, and uses the tensimeter that is connected with pipeline to measure and (in fact press P among Fig. 1 G≈ P RoWith R * l relation, with P GIndex is converted into R * l indication, directly measures R * l value); Utilize the adjustable for height linker that test(ing) liquid (ethanol or water) is housed,, in the hopper that surrounds with organic glass, inject liquid, and flooded pressure head (5) by sending leakage fluid dram (12).Enter gas flow in the cavity V with the solenoid valve gate control, make it pressure and slowly raise, as on the pipe cap insulator small opening being arranged, its R * l value just can produce bubble and detect small opening and leak rate thereof in wait observing time of regulation in the leak detection range of sensitivity from small opening.When tested part dimension, shape not simultaneously, replaceable suitable pressure head (5) is realized the detection of small opening with same method.When the leak rate of small opening extremely hanged down, it was very little to produce bubble volume, and the naked eyes Direct observation is difficulty relatively, and available 5~10 times magnifier is observed.
The test condition of leakage rate measurement and sealing screening is given an example:
1. leakage rate measurement:
Give cavity V inflation, its pressure is exceeded, can produce a small amount of bubble so that satisfy P G-P Ro<<1 * 10 5The handkerchief condition reaches P G≈ P RoPurpose, thereby just determined leak detection sensitivity R * l.The unit of tensimeter indicated value is an atmospheric pressure, P nAnd P GThe pass be P M=P G-1(≈ P Ro-1) (unit is an atmospheric pressure).Whenever-P GIt is relevant with the small opening length l that the time △ t that produces bubble is observed in following wait.After determining small opening length from component structural, also just determined △ t, also can try to achieve leak rate R simultaneously from R * l value.The test condition of two kinds of test(ing) liquids is listed table 1 and table 2 in.
2, sealing screening:
With ethanol is test(ing) liquid, and requiring the leak rate of screening is 1 * 10 -9Handkerchief rice 3/ second, promptly require leak rate to screen fully greater than the parts in addition of this value.Estimate from component structural and small opening length 1=1 * 10 -3Rice.The sensitivity requirement of then hunting leak is R * l=10 -12Handkerchief rice 4/ second.Draw from table 1, requiring to give cavity V inflation pressure is 2.4 atmospheric pressure; After reaching this pressure value, wait for and observing for 5 seconds that every generation bubble person is all leak rate 〉=1 * 10 -9Handkerchief rice 3/ second, sealing is defective.
Table 1 is the leak test condition of test(ing) liquid with ethanol
R×l R r0P G-R r0P M=P G-1 △t
(handkerchief rice 4/ second) (* 10 5Handkerchief) (* 10 5Handkerchief, or atmospheric pressure) (atmospheric pressure) (second)
10 -71.10 <<0.1 0.10 ≤1
10 -81.18 <<0.1 0.18 ≤1
10 -91.30 <<0.1 0.30 ≤1
10 -101.55 0.1 0.65 3×10 2×1
10 -112.2 0.1 1.3 10 3×1
10 -123.3 0.1 2.4 5×10 3×1
5×10 -133.8 0.1 2.9 8×10 3×1
10 -135.6 0.1 4.7 1.6×10 4×1
5×10 -146.7 0.3 6.0 2.5×10 4×1
10 -1410.1 0.3 9.4 5×10 4×1
Table 2 is the leak test condition of test(ing) liquid with water
R×1 R r0P G-R r0P M=P G-1 △t
(handkerchief rice 4/ second) (* 10 5Handkerchief) (* 10 5Handkerchief, or atmospheric pressure) (atmospheric pressure) (second)
10 -51.15 <<0.1 0.15 ≤1
10 -61.20 <<0.1 0.20 ≤1
10 -71.35 <<0.1 0.35 ≤1
10 -81.60 <<0.1 0.60 ≤1
10 -92.10 <<0.1 1.10 ≤1
10 -103.00 0.1 2.10 5×10 2×1
5×10 -113.50 0.1 2.60 8×10 2×1
10 -114.70 0.1 3.80 1.5×10 2×1
5×10 -125.50 0.1 4.60 3×10 3×1
10 -128.50 0.1 7.60 6×10 3×1
5×10 -1310.50 0.3 9.80 10 4×1

Claims (3)

1, a kind of being used to encapsulates the method that the parts small opening detects, and this method comprises following step:
A. unit under test and leakage detection apparatus are constituted the cavity that can inflate;
B. use 1~2 centimetre of the tested parts of the topped mistake of test(ing) liquid dark;
C. fill gas with the pipeline of gas cylinder by leakage detection apparatus to cavity with certain air pressure;
Whether d. observe has bubble to produce in the liquid;
This method is characterised in that the leak rate R that calculates small opening by following formula:
Various symbols are defined as in the formula:
The R-leak rate
L-small opening length
η-air viscous system
α-test(ing) liquid surface tension coefficient
The A-gas law constant
The T-gas temperature
M-air molecule amount
r C-bubble radius
P d-constant P d=1 * 10 5Handkerchief
P Ro-critical pressure
P G-cavity inflation pressure
P Ro-radius is r cBubble in gas pressure intensity
P aAtmospheric pressure △ t-forms the time of a bubble on the-liquid
R MThe leak rate of-molecular flow motion decision
R LThe leak rate of-viscous flow motion decision
2, detection method according to claim 1 is characterized in that described test(ing) liquid can be water or ethanol.
3, the leakage detection apparatus that is used for the described detection method of claim 1 comprises spanner 1, housing screw 2, cross bar 3, straight pin 4, pressure head 5, vertical rod 6, organic glass cover 7, tested shell 8, seal gasket 9, pedestal 10 is characterized in that by base 11 vertical rod 6, cross bar 3 constitutes a steel skeleton, and cross bar 3 is connected by straight pin 4 with vertical rod 6 and can relatively rotates, and housing screw 2 passes from cross bar 3 centers, both are for being threaded, and pressure head 5 is withstood in the bottom of housing screw 2, and pressure head 5 is pushed down the edge of tested shell 8.Pedestal 10 places on the base 11 and is fixedly connected, air-filled pore is opened at the pedestal center, one side is opened topping up hole and UNICOM's gas ducting 13 and liquid-filling pipe 12, unit under test 8 is placed in the air-filled pore top, unit under test 8 is combined closely through seal gasket 9 and pedestal 10 under the pressure of pressure head 5, form an inflatable cavity, pressure head 5 sides have viewport, plexiglass tent 7 place on the pedestal 10 and with pedestal 10 also for being tightly connected, perforate in the middle of the plexiglass tent 7, screw 2 therefrom passes, screw 2 upper end perforates, spanner 1 passes from the hole, test(ing) liquid from liquid-filling pipe 12 and topping up hole by and be injected into by plexiglass tent 7, pedestal 10, the vessel space that seal gasket 9 and pressure head 5 constitute.
CN 87106017 1987-08-29 1987-08-29 Leak detection and screening test for packaged details CN1013409B (en)

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CN106052969B (en) * 2015-09-23 2018-04-27 方正阀门集团有限公司 Gas leak detection apparatus and method at a kind of valve rod filler
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* Cited by examiner, † Cited by third party
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