CN101256134B - Method for measurement of printed circuit gold-plating layer porosity - Google Patents
Method for measurement of printed circuit gold-plating layer porosity Download PDFInfo
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- CN101256134B CN101256134B CN2008100442266A CN200810044226A CN101256134B CN 101256134 B CN101256134 B CN 101256134B CN 2008100442266 A CN2008100442266 A CN 2008100442266A CN 200810044226 A CN200810044226 A CN 200810044226A CN 101256134 B CN101256134 B CN 101256134B
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Abstract
The invention provides an inspection method of printed circuit board gold plating layer porosity, which belongs to the field of the chemical industry technique, relating to the detection of the printed circuit board surface gold plating layer, and particularly is suitable for detecting the printed plate conducting wire and the porosity of golden finger gold plating layer. The principal ingredientof the test solution is HCl, NaCl and osmotic agent, which produces obvious corrosion products at the discontinuous points of the gold plating layer at a certain temperature and time, transparent gridmaterial with graduates and clinohedral are used for supplementary observation, pore space sizes are weighted processed, the porosity is observed and calculated under the microscope. The invention has the merits of fast speed, convenience, accuracy and safety, which meets the surface quality detection need in the production process of the printed circuit board.
Description
Technical field
The invention belongs to chemical technology field, relate to the detection of printed circuit board surface gold-plating layer, the porosity that is particularly useful for printed board lead and golden finger Gold plated Layer detects.
Background technology
The rise of surface mounting technology (SMT) requires the printed circuit board bond pad surface coat of metal to have characteristics such as anti-oxidation, high weldability, high conductivity and high-cooling property.Organic Solderability protective finish (Organic Solderability Preservatives OSP), immersion Ni/Au or the processing of electronickelling gold surface all are well positioned to meet the SMT welding requirements and are widely used in suitability for industrialized production.
The weak point of Organic Solderability protective finish (OSP) technology be formed diaphragm as thin as a wafer, be easy to scratch (or scratch), meticulously operation and amplifier.Simultaneously, variable color or crack can take place in the OSP film of process multiple high temp welding process, influence weldability and reliability.Transparent OSP layer thickness is not easy to measure, and the coverage rate degree also is not easy to find out, the quality stability assessment of these aspects has been caused not little difficulty for the upstream purchaser.
Chemical nickel plating gold or electronickelling gold surface are handled and can be made the printed circuit board (pcb) bond pad surface very smooth, good weldability.Secondly since the chemical inertness of gold in normal environment make its can be in quite long period protection PCB bond pad surface oxidation can not take place, to have other process of surface treatment not available to the resistivity of environmental attack and good electrical property.Wearing quality when having improved plug simultaneously reduces contact resistance, has improved connection reliability.
Nickel gold (Ni/Au) overlay coating plates by plating or electroless plating cover soldering-resistance layer on printed circuit board after.The effect of nickel (Ni) layer is as the restraining barrier, stops copper and golden counterdiffusion mutually, improves the reliability of electronic interconnection.The effect of gold (Au) layer is to improve wearing quality, reduce contact resistance, prevent the oxidation of copper/nickel and improve connection reliability.Porosity is exactly an important successional index of sign nickel gold (Ni/Au) overlay coating.
At present the detection method to the gold plate surface porosity factor mainly is divided into three major types: 1. gaseous exposure method; 2. electrolysis video picture method of testing; 3. salt-fog test.In standard GB/T 17720-1999 (commentary of metal cladding ferroxyl test), GB/T4677-2002 (PCB testing method) has done specified in more detail to the porosity method of inspection of nickel gold plate on the copper matrix among the GB/T19351-2003 (metal cladding measurement method of porosity nitric acid vapor test on the metal cladding metallic matrix).
1. gaseous exposure method
The gas that uses in this method mainly contains sulphuric dioxide, sulfuretted hydrogen, chlorine, nitric acid vapor etc.Test reagent, test unit and experimental enviroment are had higher requirements, and consuming time long, and gases used equal tool strong impulse and toxicity, can cause severe contamination to atmosphere, also there is potential safety hazard in the test operation person.Assay is to calculate porosity by low power optical microscope observation rust staining number and extent of corrosion, and it is bigger that accuracy is influenced by operating personnel.The availability of this method of testing and the fiduciary level of test result are not high.
2. electrolysis video picture method of testing
This method mainly contains acrylamide electrolytic trial, the test of dimethylglyoxime paper electrolysis phenomenon, the test of cyclohexanedionedioxime paper electrolysis phenomenon, and this method is simple to operate, and it is less that assay is influenced by operating personnel.Shortcoming is to need special instrument, and its test paper and developer need special the making, and the detecting operation that relates to coating such as gold, palladium, rhodium on the nickel coating is poisonous operation, thereby has only minority printed board manufacturer in use.
3. salt-fog test
This method is mainly used sodium chloride solution at a certain temperature, the long-time interior spraying that continues.This method is simple to operate, and shortcoming is to need special instrument, and is consuming time too of a specified duration, is difficult for accurately calculating porosity.Present most printed board manufacturer estimates quality of coating qualitatively with this method.
Summary of the invention
The present invention aims to provide a kind of method of inspection of quick, easy, accurate, safe printed board nickel plating gold layer porosity.Reaction principle is that the parent metal that utilizes the discontinuous place of suitable reagent and overlayer to expose works and forms observable corrosion product.Test solution consists of hydrochloric acid, sodium chloride and bleeding agent etc.This method is not seen the related data report at home and abroad as yet.
Technical scheme of the present invention is:
A kind of method for measurement of printed circuit gold-plating layer porosity may further comprise the steps:
Step 1. preparation test solution
The aqueous solution that preparation is mixed by HCl, NaCl, bleeding agent, each constituent mass percentage composition is: HCl:2%～2.7%, NaCl:0.5～2.0%, bleeding agent: 0.02%～0.2%, all the other are H
2O.Wherein bleeding agent is to contain composite dose of following one or more surfactants: aliphatic alcohol polyethenoxy (5～6) ether, aliphatic acid polyethenoxy ether, sodium alkyl naphthalene sulfonate, nekal and sodium butylnaphthalenesulfonate.The effect of bleeding agent is the osmosis that strengthens solution, improves the exposure level of test solution and coating.
Step 2. is cleaned the greasy dirt that the testing sample surface may exist.Testing sample need have exposed coating, as golden finger, ground connection copper sheet, pad etc.Can adopt ethanol as clean-out system during concrete the cleaning.
Step 3. is put into the testing sample after surface degreasing is handled and is detected solution, and the control solution temperature is at 21 ℃-24 ℃, leave standstill 5～8 minutes after, take out testing sample and also remove the moisture on testing sample surface.
It is on the inclined-plane between 0.15～0.25 (as shown in Figure 1) that step 4. is positioned over inclination angle tan α with testing sample, adopts the hole on low power optical microscope observing samples surface.Total observation area is not less than 50% of the total coating area of sample.
Step 5. is calculated porosity.Number goes out the interior number of pores of institute's area of observe in the step 4, the calculating porosity (number of pores/centimetre
2).Hole calculates according to table-1 and carries out.
Table-1 pore size computing method
| Pore-size | Calculate the hole number |
| Maximum gauge≤0.05mm | 0 |
| 0.05mm＜maximum gauge＜0.1mm | 1 |
| 0.1mm≤maximum gauge＜0.2mm | 2 |
| Maximum gauge 〉=0.2mm | 5 |
Remove the way that the concrete grammar of the moisture on testing sample surface can adopt nature to dry, dry described in the above-mentioned steps 3, also can adopt thieving paper to draw the moisture of sample surfaces.
The α of inclination angle tan described in the above-mentioned steps 4 is that the inclined-plane between 0.15～0.25 can utilize the clinohedral with identical inclination angle tan α to realize.
When adopting the hole on low power optical microscope observing samples surface in the above-mentioned steps 4, can adopt live width is that 0.1 millimeter, spacing are that 1 millimeter transparent square net material (as shown in Figure 2) is installed on the eyepiece below of low-power microscope to improve the measuring accuracy of the number of pores in the calculating observation area.Described transparent square net material can adopt making such as transparent film, transparency paper or clear glass.
Reaction between test solution and coating and hole test philosophy:
(1) reaction mechanism
Flexible printed-circuit board manufacturer is for increasing the resistance to deflection of product, and the plating nickel-gold layer is very thin, the general about 1.5 μ m of nickel dam, gold layer 0.02-0.1 μ m.Gold plated Layer for reaching effective covering protection of Gold plated Layer, is used the end-capping reagent of Organic Solderability protective finish (OSP) as Gold plated Layer as thin as a wafer in the production.Protective finish is extremely meagre diaphragm, not with hydrochloric acid reaction.
The reaction mechanism of measuring porosity is in acid solution, hydrochloric acid penetrates into nickel coating by the hole that is not covered by Gold plated Layer under the effect of bleeding agent, and with coating nickel generation redox reaction, nickel is dissolved, stay fine pin hole, be may observe and calculate micropore quantity at low-power microscope.Its reaction mechanism is as follows:
Ni+2HCl→NiCl
2+H
2↑
Sodium chloride provides electrolyte environment for system, and metallic nickel is as the negative pole of corrosion galvanic cell, and gold forms corrosion galvanic cell as the positive pole of corrosion galvanic cell, has quickened the pin-hole corrosion of original existence.The pin-hole corrosion effect is shown in figure-3.
The corrosion galvanic cell electrode reaction is as follows:
Primary element reaction negative pole: Ni-2e → Ni
2+
The primary element reaction is anodal: 2H
++ 2e → H
2
(2) sample is placed on and observes reason on the clinohedral
Because hydrochloric acid does not react with copper, bottom is the copper layer after the nickel stripping in the pin hole, when irradiate light, gold face reflection ray, hole also can reflection ray, thereby weakens the discrimination of hole and golden face, if do not adopt certain inclined-plane can't differentiate hole (as shown in Figure 4) under optical microscope.Therefore the present invention adopts the angle of inclination to increase echo area calibration (as shown in Figure 5).
(3) influence of the effect of each composition of test solution and temperature-time
The effect of HCl: the principal ingredient of test solution provides sour environment, with exposed nickel reactant.
The effect of NaCl: ion is provided, quickens the pin-hole corrosion effect.
The effect of bleeding agent: as acidproof bleeding agent, strengthen the osmosis of solution, improve the exposure level of test solution and coating, reaction is had facilitation.
Temperature: temperature to reaction rate influence significantly, temperature is too high to be swift in response, hole extremely enlarges and causes nickel dam dissolved at last, golden pull-up falls.Should select suitable temperature in conjunction with working condition, be advisable for general 21 ℃-24 ℃.
Time: soak time is bigger to hole influence, and the time is of a specified duration more, and the nickel of stripping is many more, and hole is big more, but the time after causing nickel dam to dissolve fully for a long time, golden pull-up falls, general 5～8min is advisable.
Beneficial effect of the present invention:
1, the invention provides a kind of method of inspection of quick, easy, accurate, safe printed board nickel plating gold layer porosity, satisfy the surface quality that industrialization produces and detect requirement.
2, test solution principal ingredient of the present invention is hydrochloric acid, sodium chloride and bleeding agent, and with the reaction of Organic Solderability protective finish, the porosity of mensuration is not the porosity behind the end-blocking, has truly characterized the quality of overlay coating.
3, the present invention adopts the solution infusion method, and the low power optical microscope is used in observation, utilizes clinohedral can observe the micro-pore that approaches on the gold plate easily.
Description of drawings
Fig. 1 clinohedral synoptic diagram of the present invention.
Transparent network grid material shape synoptic diagram under Fig. 2 installation of the present invention and the optical microscope eyepiece.
The pin-hole corrosion synoptic diagram of the main principle of reflection of Fig. 3 the present invention.
The reflection contrast synoptic diagram of Fig. 4 plane observation.
The reflection contrast synoptic diagram of Fig. 5 declivity observation.
Embodiment
Technical solution of the present invention partly is described in detail at summary of the invention, below only provides the actual test experiments data of several different testing samples, to further specify operability of the present invention and invention effect.Experiment is carried out having on the printed board single-piece of golden finger, ground connection copper sheet and pad.
Embodiment one
Add the deionized water of 100ml in the volumetric flask of 250ml, measure 11.77ml 36% dense HCl, mix, add 1.25g NaCl, add concentration again and be 10% bleeding agent 0.50ml, the dissolving back adds deionized water to scale mark fully.HCl and NaCl all use analytical reagent.
The learn from else's experience printed board (sample one) of electronickelling/flash gold process, the thickness that records the Ni layer is 3.324 μ m, the thickness of Au layer is 0.125um.Sample one removed to put into temperature behind the greasy dirt be 22 ℃ above-mentioned test solution 5min, blotting the back with thieving paper observes under the 20X optical microscope, during observation, adopting live width is that 0.1 millimeter, spacing are the eyepiece below that 1 millimeter transparent square net film egative film is installed on low-power microscope, inclination angle tan α is that the inclined-plane between 0.15～0.25 is the clinohedral with identical inclination angle tan α of utilizing rubber or timber to make, and finally calculating porosity by table-1 is 10.2/cm
2
Embodiment two
Preparing the 250ml concentration of hydrochloric acid according to the mode of embodiment one is 2.3%, and sodium chloride concentration is 1.0%, and bleeding agent concentration is 0.05% test solution.
The printed board of the electronickelling/thick metal plated technology of learning from else's experience (sample two), the thickness that records the Ni layer are 6.570 μ m, and the thickness of Au layer is 0.520 μ m.Sample two removed to put into temperature behind the greasy dirts be 21 ℃ above-mentioned test solution 8min, blotting the back with thieving paper observes under the 20X optical microscope, during observation, adopting live width is that 0.1 millimeter, spacing are the eyepiece below that 1 millimeter transparent square net film egative film is installed on low-power microscope, inclination angle tan α is that the inclined-plane between 0.15～0.25 is the clinohedral with identical inclination angle tan α of utilizing rubber or timber to make, and finally calculating porosity by table-1 is 0.3/cm
2
Embodiment three
Preparing the 250ml concentration of hydrochloric acid according to the mode of embodiment one is 2.5%, and sodium chloride concentration is 1.5%, and bleeding agent concentration is 0.1% test solution.
The learn from else's experience printed board (sample three) of heavy soft nickel/gold-leaching technology, the thickness that records the Ni layer is 1.248 μ m, the thickness of Au layer is 0.070 μ m.Sample three removed to put into temperature behind the greasy dirts be 22 ℃ above-mentioned test solution 5min, blotting the back with thieving paper observes under the 20X optical microscope, during observation, adopting live width is that 0.1 millimeter, spacing are the eyepiece below that 1 millimeter transparent square net film egative film is installed on low-power microscope, inclination angle tan α is that the inclined-plane between 0.15～0.25 is the clinohedral with identical inclination angle tan α of utilizing rubber or timber to make, and finally calculating porosity by table-1 is 25.4/cm
2
Embodiment four
Preparing the 250ml concentration of hydrochloric acid according to the mode of embodiment one is 2.7%, and sodium chloride concentration is 2%, and bleeding agent concentration is 0.15% test solution.The learn from else's experience printed board (sample four) of heavy hard nickel/gold-leaching technology, the thickness that records the Ni layer is 1.562 μ m, the thickness of Au layer is 0.02 μ m.Put into temperature after the sample cleaning politics, economics, organization, and ideology degreased and be 24 ℃ above-mentioned test solution 5min, blotting the back with thieving paper observes under the 20X optical microscope, during observation, adopting live width is that 0.1 millimeter, spacing are the eyepiece below that 1 millimeter transparent square net film egative film is installed on low-power microscope, inclination angle tan α is that the inclined-plane between 0.15～0.25 is the clinohedral with identical inclination angle tan α of utilizing rubber or timber to make, and finally calculating porosity by table-1 is 32.5/cm
2
Embodiment five
Preparing the 250ml concentration of hydrochloric acid according to the mode of embodiment one is 2.5%, and sodium chloride concentration is 2%, and bleeding agent concentration is 0.2% test solution.The printed board (sample five) of the heavy soft nickel/chemical gilding technology of learning from else's experience, the thickness that records the Ni layer is 2.324 μ m, the thickness of Au layer is 0.452 μ m.Sample five removed to put into temperature behind the greasy dirts be 22 ℃ above-mentioned test solution 8min, blotting the back with thieving paper observes under the 20X optical microscope, during observation, adopting live width is that 0.1 millimeter, spacing are the eyepiece below that 1 millimeter transparent square net film egative film is installed on low-power microscope, inclination angle tan α is that the inclined-plane between 0.15～0.25 is the clinohedral with identical inclination angle tan α of utilizing rubber or timber to make, and finally calculating porosity by table-1 is 1.2/cm
2
Claims (7)
1. a method for measurement of printed circuit gold-plating layer porosity is characterized in that, may further comprise the steps:
Step 1. preparation detects solution:
The aqueous solution that preparation is mixed by HCl, NaCl, bleeding agent, each constituent mass percentage composition is: HCl:2%～2.7%, NaCl:0.5～2.0%, bleeding agent: 0.02%～0.2%, all the other are H
2O; Wherein bleeding agent is to contain composite dose of following one or more surfactants: aliphatic alcohol polyethenoxy (5～6) ether, aliphatic acid polyethenoxy ether, sodium alkyl naphthalene sulfonate, nekal and sodium butylnaphthalenesulfonate;
Step 2. is cleaned the greasy dirt that the testing sample surface may exist, and testing sample need have exposed coating, and coating is golden finger, ground connection copper sheet or pad;
Step 3. is put into the testing sample after surface degreasing is handled and is detected solution, and the control solution temperature is at 21 ℃-24 ℃, leave standstill 5～8 minutes after, take out testing sample and also remove the moisture on testing sample surface;
It is on the inclined-plane between 0.15～0.25 that step 4. is positioned over inclination angle tan α with testing sample, adopts the surperficial hole of low power optical microscope observation bar product; Total observation area is not less than 50% of the total coating area of sample;
Step 5. is calculated porosity:
Table-1 pore size computing method
Number goes out the interior number of pores of institute's area of observe in the step 4, the calculating porosity, promptly number of pores/centimetre
2Hole calculates according to table-1 and carries out.
2. method for measurement of printed circuit gold-plating layer porosity according to claim 1 is characterized in that, when described step 2 is cleaned the greasy dirt that the testing sample surface may exist, adopts ethanol as clean-out system.
3. method for measurement of printed circuit gold-plating layer porosity according to claim 1 is characterized in that, the concrete grammar of removing the moisture on testing sample surface described in the step 3 is the way that adopts nature to dry or dry.
4. method for measurement of printed circuit gold-plating layer porosity according to claim 1 is characterized in that, the concrete grammar of removing the moisture for the treatment of measuring staff product surface described in the step 3 is to adopt thieving paper to draw the way of the moisture of sample surfaces.
5. method for measurement of printed circuit gold-plating layer porosity according to claim 1 is characterized in that, the tan α of inclination angle described in the step 4 is that the inclined-plane between 0.15～0.25 is to utilize the clinohedral with identical inclination angle tan α to realize.
6. method for measurement of printed circuit gold-plating layer porosity according to claim 1, it is characterized in that, when adopting the hole on low power optical microscope observing samples surface in the step 4, adopting live width is that 0.1 millimeter, spacing are that 1 millimeter transparent square net material is installed on the eyepiece below of low-power microscope to improve the measuring accuracy of the number of pores in the calculating observation area.
7. method for measurement of printed circuit gold-plating layer porosity according to claim 6 is characterized in that, described transparent square net material adopts transparent film, transparency paper or clear glass to make.
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| CN101657069B (en) * | 2009-08-28 | 2011-12-28 | 华为终端有限公司 | Surface processing method for printed circuit board and corresponding printed circuit board |
| CN102072904B (en) * | 2010-11-11 | 2012-06-27 | 广东生益科技股份有限公司 | Water permeability resistance verifying method for flexible single-sided copper clad plates |
| CN102116730B (en) * | 2010-12-09 | 2013-10-16 | 中兴通讯股份有限公司 | Method for testing porosity of electric connector gold-plating layer |
| CN102636423A (en) * | 2011-02-12 | 2012-08-15 | 宝山钢铁股份有限公司 | Detection method of tin plate porosity |
| CN103645187B (en) * | 2013-12-31 | 2015-12-30 | 广州天至环保科技有限公司 | A kind of test agent of online Fast nondestructive evaluation gold plate quality and using method |
| CN105628694A (en) * | 2015-12-24 | 2016-06-01 | 大连理工大学 | Test paper and method for detecting integrity of copper coating or chromium coating on steel surface |
| CN107271450A (en) * | 2017-06-20 | 2017-10-20 | 深圳市华星光电技术有限公司 | A kind of detection method of polyamide/silicon nitride film compactness |
| CN109975194A (en) * | 2019-04-26 | 2019-07-05 | 广东天承科技有限公司 | A kind of electroplated layer porosity measurement device and measurement method |
| CN114563322B (en) * | 2022-01-28 | 2023-12-19 | 武汉理工大学 | Characterization and regulation method for aluminum alloy surface corrosion microstructure in aluminum alloy/polymer laminated material |
| CN115082478B (en) * | 2022-08-23 | 2022-11-18 | 凤芯微电子科技(聊城)有限公司 | Integrated circuit board quality sorting system |
| CN116625907A (en) * | 2023-07-24 | 2023-08-22 | 中国矿业大学(北京) | Method for testing porosity of lithium ion battery diaphragm |
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