On Ultra-Fine Leak Detection of Hermetic Wafer Level Packages

Theoretical and practical ranges of leak rates measurable by the helium mass spectrometer are characterized. The effect of noise due to: 1) background helium present in the spectrometer and 2) desorption of helium that attaches itself to the specimen surface during bombing is quantified experimentally. The results guide a framework to extract the true leak rate from the measured leak rate profile. An optical interferometry based hermeticity measurement technique for ultra-fine leaks is proposed. The setup to implement the technique is described and a preliminary experimental result is reported.     

氦质谱检漏试验方法分析

从电子元器件气密性封装的原理入手,介绍了常用的检漏试验方法,阐述了美军标MIL-STD-883氦质谱检漏试验方法的最新发展,分析了积累氦质谱试验方法的特点及要求,并探讨了基于氦气交换时间常数τHe的氦质谱检漏思路。     

On the applicability of MIL-Spec-based helium fine leak test to packages with sub-micro liter cavity volumes

The MIL-Spec-based helium fine leak test (test condition A₁ and test condition A₂) is reviewed for its applicability to packages with sub-micro liter cavity volumes. The existing gas conduction models are utilized to investigate the validity of the criteria defined in the test guidelines in terms of true leak rates. The application domains valid under the current guidelines are determined as a function of the internal cavity volume. The results show that the test is valid only for a finite domain of true leak rates when the volume is smaller than 10^?2 cm³ and the invalid domain increases as the cavity volume decreases.     

元器件氦质谱检漏失效判据的分析

比较了现行国军标中氦质谱检漏固定法与灵活法标准判据,在相同条件下,2种方法的判据有数量级上的差别。相同内腔体积的半导体分立器件、电子及电气元件和微电子器件,由于器件种类不同,封装、工艺等不同,细检漏的判据仍然存在较大差别。分析了美军标中氦质谱检漏标准判据,指出国军标和美军标氦质谱检漏标准判据存在一定的不适用性,建议元器件氦质谱检漏的标准判据应进一步改进。     

Forward-stepwise regression analysis for fine leak batch testing of wafer-level hermetic MEMS packages

An advanced regression scheme is proposed to analyze fine leak batch testing data of multiple MEMS packages. The scheme employs the forward-stepwise regression method to infer the information of leaky packages from a batch test data. The analysis predicts the number of leaky packages and the true leak rate of each leaky package in a progressive manner. The scheme is implemented successfully using an actual batch test data obtained from wafer-level hermetic MEMS packages. An error analysis is followed to define the applicable domain of the scheme. Advanced formulations are also suggested to extend the applicable domain.     

一种适用于微电子器件的密封漏气分析方法

关于微电子器件密封失效的分析方法多种多样,并且各有优缺点。对大漏孔的器件,通过氟油粗检可判断出漏气的具体位置。而对于漏孔较小的微漏器件,确定漏孔位置是非常困难的。根据气体分子机理和氦泄漏原理模型,提出了一种氦泄漏通道局部测试法来确定漏点的位置,从而解决了微漏器件漏点分析难题。通过大量试验数据对比分析,验证了该方法的有效性与准确性。     

Theoretical investigation on hermeticity testing of MEMS packages based on MIL-STD-883E

In the present study, a gas flow model is used to show that the helium bomb test and bubble test methods in MIL-STD-883E are not applicable for hermeticity testing of packages with small internal volumes (<10⁻³ cm³), typically encountered for microelectromechanical systems (MEMS). The reasons include inaccurate reading due to helium loss in dwell period, undefined regime in leak rate spectrum, and unpractical reject limit for small vacuum packages. The simulation results indicate the necessity to develop new test methods for hermeticity testing of MEMS packages, such as to integrate pressure sensors in the package.     

用于红外探测器组件检测的超高灵敏度检漏仪

提出了一种采用累积法进行超高灵敏度氦质谱检漏的先进技术,基于该技术及相关材料特殊处理工艺设计并研制出了新型超高灵敏度检漏仪器,检测灵敏度优于8×10-15 atm.cc/s.He,是常规氦质谱检漏仪器灵敏度的1000倍以上,已成功应用于红外焦平面探测器组件等长寿命真空电子元器件产品的研制和生产工艺检测中,也是高能粒子加...     

压氦法和预充氦法氦质谱细检漏固定方案的设计

以“氦质谱细检漏的基本判据和最长候检时间”为基础,分析了密封电子元器件内部水汽不超过5 000 ppm的可靠贮存寿命,确定了细漏检测的严密等级THemin分级,界定和拓展了适用内腔容积并进行了分段,设计了压氦法和预充氦法的固定方案,验证了固定方案规定的最长候检时间可以满足去除吸附氦的要求.从而突破了国内外相关标准改进中难以或无法实施的技术瓶颈,为加严密封性判据改进相关标准,提供了可行的技术方案.     

多次压氦法和预充氦压氦法质谱细检漏方法研究

密封电子元器件在长时间存放后,会存在无法检测的现象.当超过密封件细漏检测的最长候检时间时,应再次压氦,然后进行细检漏.按现行的各种规范的规定,压氦法和预充氦法再压氦的条件、程序和判据一般均与首次压氦相同,但分析表明,这样可能会使测量漏率判据出现成倍或更大的偏差,有时会出现大漏的漏检和细漏的错判.推演出多次压氦法和预充氦压氦法的测量漏率判据公式,给出了相应的压氦条件和细检漏的最长候检时间,从而更为便捷准确地解决了长候检时间下的密封性检测问题.     

Cu–Cu Hermetic Seal Enhancement Using Self-Assembled Monolayer Passivation

Low-temperature Cu–Cu thermocompression bonding enabled by self-assembled monolayer (SAM) passivation for hermetic sealing application is investigated in this work. Cavities are etched to a volume of 1.4 × 10^?3 cm³ in accordance with the MIL-STD-883E standard prescribed for microelectronics packaging. The wafer pairs (nonfunctional cavity wafer and cap wafer) are annealed and bonded at 250°C under a bonding force of 5500 N. The encapsulated cavities undergo helium overpressure in a bombing chamber, and the helium leak rate is detected by a mass spectrometer. The measurement results show that the cavities sealed with Cu–Cu bonding after SAM passivation exhibit excellent hermeticity with a leak rate below 10^?9 atm cm³/s, which is an improvement of at least 2× compared with the control sample without SAM passivation.     

Water vapor penetration rate into enclosures with known air leak rates

The rate at which water vapor penetrates a faulty seal in a "hermetically sealed" device has been examined both experimentally and theoretically in this study. The experimental data were generated by studying the rate of moisture ingress into two types of packages; a TO-5 can and a ¼ × ¼ in ceramic flatpack. The TO-5 packages were fitted with capillary tubes of varying diameters with known air leak rates and represented the gross leak range (down to 10^-5atm . cm³/s) while the ¼ × ¼ in ceramic flatpacks were used to study the fine leak range (10^-6to 10^-8atm . cm³/s). Both type packages were fitted with miniature moisture sensors (surface conductivity type) and calibrated at known relative humidities prior to sealing. The finished test packages were then exposed to constant high-humidity conditions and monitored for moisture content as a function of time. A theoretical analysis was performed by using conventional leak rate equations to convert air leak rates, at standard test conditions, to water vapor leak rates at partial pressure differentials seen typically at room ambient conditions. These data compared favorably with the experimental results in the range tested and suggests that present hermeticity specifications are too lenient for long-term reliability requirements.     

去除吸附氦试验及相关标准分析

介绍了两种典型的密封样品的去除吸附氦试验,吸附氦漏率的测试是在Inticon公司Pemicka700H型积累氮质谱粗漏细漏组合检漏仪上进行的。给出了试验数据、拟合模式和结果,进而分析了最新的美国军用标准MIL-STD-750—1／883J氯质谱检漏方法在降低被检件吸附氦漏率方面的不可检测性．并综合分析了这两项标准的其他问题,提出了全面改进的方案。     

以内部气体质谱分析检测元器件密封性的方法

基于内外气体交换的分子流模型,采用了以τHemin为基本判据和定量确定最长候检时间的方法,提出了以内部气体质谱分析检测元器件密封性的方法及其氦气含量法和氩气含量法,给出了这种方法的判据公式、压氦或压氩压力时间和最长候检时间公式或确定方法,规定了检测判定程序。内部气体质谱分析,需要时辅以粗漏检测,能够进行具有更高灵敏度和准确性的、破坏性的密封性检测,可用于鉴定检验、周期检验和认证性检测。     

Leak detection—Ultrasensitive techniques employing the helium leak detector

The development of closures for electron devices often requires that leaks far below the usual range of the helium mass spectrometer-type leak detector be localized and measured. It has been possible, by using new techniques, to extend the sensitivity of detection several orders of magnitude beyond the normal limit of the instrument. Two highly sensitive methods with similar techniques but separate sensitivity ranges are discussed. In seals similar to those of color television picture tube closures, it is noted that the character of small leaks is such that long times are required to reach a constant maximum rate of helium leakage. Methods for predicting this maximum rate from early observations are discussed. Methods for establishing procedures necessary for sensitivity requirements for any particular seal type are given. Time and sensitivity limitations are discussed. Increases in the sensitivity of detection of the order of 40,000 are attained easily. Leaks as small as 1.5 × 10^-10µliters/second have been detected and measured in 22-inch rectangular color television picture tube closure seals. In one year, a leak of this size would only cause an increase in pressure in an ungettered tube of 10^-7mm Hg. This represents an increase in the sensitivity of detection of about one million.     

漏率公式与判据和内部气体含量的分析研究(一)

在对氦质谱细检漏漏率公式的分析和对密封腔体内外气体交换过程公式的推演中,以氦气标准漏率LHe代替等效标准漏率L,引用了氦气交换时间常数τHe,使公式更为真实和简单直观。通过漏率偏差的分析和内部气体含量的计算表明,能够应用文中的公式对密封腔体内外气体的交换过程进行工程计算。计算分析了现行某些标准中各种试验条件漏率判据所对应的τHe,着重指出漏率符合接收判据并不能有效保证内部水汽含量要求。讨论了这些标准中进行的改进、存在的密封性等级及进一步改进的必要,并提出了建议进行研究的内容。     

漏率公式与判据和内部气体含量的分析研究(二)

在对氦质谱细检漏漏率公式的分析和对密封腔体内外气体交换过程公式的推演中,以氦气标准漏率LHe代替等效标准漏率L,引用了氦气交换时间常数τHe,使公式更为真实和简单直观。通过漏率偏差的分析和内部气体含量的计算表明,能够应用本文的公式对密封腔体内外气体的交换过程进行工程计算。计算分析了现行我国国家标准和美国标准各种试验条件漏率判据所对应的τHe,着重指出漏率符合接收判据并不能有效保证内部水汽含量要求。讨论了这些标准中进行的改进、存在的密封性等级及进一步改进的必要,并提出了建议进行研究的内容。     

漏率公式与判据和内部气体含量的分析研究(三)

在对氦质谱细检漏漏率公式的分析和对密封腔体内外气体交换过程公式的推演中,以氦气标准漏率LHe代替等效标准漏率L,引用了氦气交换时间常数τHe,使公式更为真实和简单直观。通过漏率偏差的分析和内部气体含量的计算表明,能够应用本文的公式对密封腔体内外气体的交换过程进行工程计算。计算分析了现行我国国家标准和美国标准各种试验条件漏率判据所对应的τHe,着重指出漏率符合接收判据并不能有效保证内部水汽含量要求。讨论了这些标准中进行的改进、存在的密封性等级及进一步改进的必要,并提出了建议进行研究的内容。     

Evaluating IC-package interface delamination by consideringmoisture-induced molding-compound swelling

We have determined the influence of moisture soaking conditions on true adhesion strength measured by our previously developed method. The drop in true adhesion strength of a specimen that absorbed moisture at 50°C is about 50% less than that of a specimen at 85°C. This result suggests that the true adhesion strength depends on not only the moisture content but also the moisture absorption temperature. Therefore, we think that the general moisture condition (85°C/85%) causes more damage to plastic integrated circuit (IC) packages than that of moisture absorption at room temperature. We also evaluated interface delamination in a moisture-absorbed package by considering the swelling of the molding compound due to moisture absorption. The predicted interface delamination agrees well with the experimental data for moisture-soaked packages     

AlN多层共烧陶瓷微波外壳的设计与制作

使用Ansoft HFSS软件设计了一种微波多芯片组件(MCM)用陶瓷外壳,并采用AlN多层共烧陶瓷工艺制作了样品。微波输入输出(I/O)端子采用微带线直接穿墙形式,并与陶瓷外壳一体设计、制作。试验结果表明,在2～12 GHz内驻波比(VSWR)<1.3,测量漏率R1≤1×10–3Pa.cm3/s(He)。