Modeling of temperature-humidity for wood drying based on time-delay neural network

The temperature-humidity models of wood drying were developed based on Time-delay neural network and the identification structures of Time-delay neural network were given. The controlling model and the schedule model, which revealed the relation between controlling signal and temperature-humidity and the relation between wood moisture content and temperature-humidity of wood drying, were separately presented. The models were simulated by using the measured data of the experimental drying kiln. The numerical simulation results showed that the modeling method was feasible, and the models were effective.

Warpage prediction of the injection-molded strip-like plastic parts

For most strip-like plastic injection molded parts, whose cross section size is much smaller than their length, the traditional Hele-Shaw model and three-dimensional model do not work well in the prediction of the warpage be- cause of their special shape. A new solution was suggested in this work. The strip-like plastic part was regarded as a little-curved beam macrnscopically, and was divided into a few one-dimensional elements. On the section of each elemental node location, two-dimensional thermal finite element analysis was made to obtain the non- uniform thermal stress caused by the time difference of the solidification of the plastic melt in the mold. The stress relaxation, or equivalently, strain creep was dealt with by using a special computing model. On the bases of in-mold elastic stress, the final bending moment to the beam was obtained and the warpage was predict- ed in good a^reement with practical cases.

Development of Temperature-Humidity Independent Control Air-Conditioning Unit for Residential Buildings

Cooling panels are increasingly used in domestic residential buildings.To provide medium temperature cold water for the cooling panel,and dehumidify the indoor air simultaneously,a new kind of temperature-humidity independent control air-conditioning unit was developed for single residential house by utilizing multi-variable technology.First,the supply air temperature was studied to determine the proper supply air flow rate for the humidity control.Then,the energy consumption of different temperature-humidity independent control systems was studied.The analysis indicates that unity evaporating temperature can be used to handle the moisture load and sensible heat load in two evaporators.So the unit scheme was put forward.Two evaporators were used to produce medium temperature water and dry air separately,and electric expansion valves were used to control the refrigerant distribution between the two evaporators.Then,experimental work was carried out to investigate the influence of compressor frequency,refrigerant distribution on the dehumidification capacity,energy efficiency and refrigeration capacity.In the end,the paper concludes that both compressor frequency and refrigerant distribution can control the dehumidification capacity,but the former influences the EER more than the latter,while the latter influences the refrigeration capacity more than the former.We can find a proper running point at certain sensible and latent cooling load by adjusting both compressor frequency and electric expansion valve.The energy consumption of this kind of unit was estimated and compared with present room air conditioners,which shows that it can save about 41% cooling energy consumption.

Effects of process parameters on warpage of rapid heat cycle moulding plastic part

The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively.

Study of the Preparation Technology and Mechanics of the Compound Temperature-Humidity Sensor

The development and character of compound temperature-humidity sensor were discussed in this study.The design of sampling,control and output unit of temperature-humidity sensor as well as their manufacture method and character were studied in detail.The relationship between components of humidity resistance materials and negative temperature coefficient ( NTC) thermistor materials in sampling unit of compound sensor and character of electrical resistance and temperature was obtained.Couples of character curves of compound temperature-humidity sensor and data of materials of sampling unit were shown in this paper too.

Pre-compensation of Warpage for Additive Manufacturing

Additive manufacturing technologies enable the production of parts by successively adding layers. In powder-based technologies, each powder layer is selectively solidified following the respective cross-section of the parts either by the application of high-energy radiation or by the selective deposition of binder. By repeating the steps of layer deposition and selective solidification, parts are fabricated. The layer-wise build-up and the ambient conditions lead to warpage of the parts due to the temporarily and locally uneven distribution of shrinkage throughout the part. This leads to deviations in shape and dimension. The development of these technologies fosters a change fi＇om prototyping to manufacturing applications, As a consequence, higher standards regarding the shape and dimensional accuracy are required. Therefore, new strategies to minimize the resulting deformations are necessary to reduce rejects and widen the range of applications of the described technologies. In this paper, an empirical, a knowledge-based and a simulative approach for warpage compensation are introduced. They are all based on the pre-deformation of the digital 3D part geometry inverse to the expected deformation during manufacturing. The aim of the research is the development of a comprehensive method that enables users to improve their part-quality by supporting the pre-deformation process. Contrary to existing work, this method should not be process-specific but cover a wide range of additive manufacturing techniques. Typical forms of deformation of the processes laser sintering, laser beam melting and 3D printing （powder-binder） are presented and compensation strategies are disenssed. Finally, an outlook on the ongoing research is given.

Effect of warpage on the electronic structure and optical properties of bilayer germanene

The electronic structure and optical properties of bilayer germanene under different warpages are studied by the first-principles method of density functional theory.The effects of warpages on the electronic structure and optical properties of bilayer germanene are analyzed.The results of the electronic structure study show that the bottom of the conduction band of bilayer germanene moves to the lower energy direction with the increase of warpages at the K point,and the top of the valence band stays constant at the K point,and so the band gap decreases with the increase of warpage.When the warpage is 0.075 nm,the top of the valence band of bilayer germanene changes from K point to G point,and the bilayer germanene be-comes an indirect band gap semiconductor.This is an effective means to modulate the conversion of bilayer germanene between direct band gap semiconductor and indirect band gap semiconductor by adjusting the band structure of bilayer ger-manene effectively.The study of optical properties shows that the effect of warpage on the optical properties of bilayer ger-manene is mainly distributed in the ultraviolet and visible regions,and the warpage can effectively regulate the electronic struc-ture and optical properties of bilayer germanene.When the warpage is 0.069 nm,the first peak of dielectric function and extinc-tion coefficient is the largest,and the energy corresponding to the absorption band edge is the smallest.Therefore,the elec-tron utilization rate is the best when the warpage is 0.069 nm.

Flash Lamp Annealing Method for Improving Adhesion Strength on the Dielectric Material and Reducing Substrate Warpage

Today’s electronic devices have required higher performance properties for 5G and artificial intelligence(AI).High-performance system on chip(SOC),graphic processing unit(GPU),and central processing unit(CPU)requires advanced packages to meet demands for performance,size,and high-speed transmission.To respond to these demands,integration approaches such as 3D IC chip stacking,package on package(PoP),2.5D interposer integration,system-in-package(SiP),and fan-out packaging technologies have emerged[6,8,11,12].Therefore,the package substrate for high-performance device will require low transmission loss and the small package warpage.Low loss materials have limitation of seed layer formation with electroless Cu plating.Also,heat treatment has major impact on substrate warpage in order for growth of plated Cu metal and curing for epoxy mold compound(EMC)process.In this paper,we believe it is possible to create a seed layer on the low-loss material by combining electroless Cu plating and flash lamp annealing(FLA)method instead of sputtering process.In terms of warpage control and metal growth,the flash lamp treatment,not the conventional convection or hot plate type heat treatment,could improve electro-migration between metal line and line through improving large number of(111)slip directions.In addition,flash lamp not only provides alternative to conventional heat treatment process but also significantly reduces substrate warpage.Through result of this study,by using FLA method for advanced package,it is possible to provide solutions in improving adhesion strength between dielectric materials and deposited metal film,and to reduce the warpage of the substrate.

Comprehensive Warpage Analysis of Stacked Die MEMS Package in Accelerometer Application

Packaging of MEMS ( micro-electro-mechanical system ) devices poses more challenges than conventional IC packaging, since the performance of the MEMS devices is highly dependent on packaging processes. A Land Grid Array ( LGA ) package is introduced for MEMS technology based linear multi-axis accelerometers. Finite element modeling is conducted to simulate the warpage behavior of the LGA packages. A method to correlate the package warpage to matrix block warpage has been developed. Warpage for both package and sensor substrate are obtained. Warpage predicted by simulation correlates very well with experimental measurements. Based on this validated method, detailed design analysis with different package geometrical variations are carried out to optimize the package design. With the optimized package structure, the packaging effect on accelerometer signal performance is well controlled.

氢离子注入钽酸锂的翘曲变化及颗粒研究

声表面波(SAW)滤波器急需使用高质量的钽酸锂压电单晶复合薄膜衬底材料来提升性能。离子注入后,晶圆翘曲增大,颗粒增加,键合工艺易产生不规则条纹和键合空洞等缺陷,严重阻碍高质量钽酸锂压电单晶复合薄膜材料的制备。通过X线衍射(XRD)、聚焦离子束透射电镜(FIB-TEM)及颗粒测试仪等设备对注入内部应力、损伤和颗粒变化进行分析表征,解释了翘曲增大和颗粒增多的原因,并提出了相应的解决方法,最后成功制备了翘曲低、颗粒少的注入晶圆。通过键合工艺进一步验证,获得了无条纹和空洞等缺陷的高质量键合晶圆,为钽酸锂压电单晶复合薄膜的高效制备奠定了基础。

回流焊工艺对SMT器件热翘曲的影响

集成电路正在向小型化、高集成度的方向发展,回流焊工艺已成为其组装过程中的关键技术。在回流焊过程中集成电路容易发生热翘曲现象。采用阴影云纹法对PBGA1296、PBGA1024器件在不同回流焊温度、升降温速率的回流焊工艺下的热翘曲进行测量,在此基础上通过建模仿真对实验结果进行分析。结果表明,采用表面贴装技术(SMT)的BGA器件的热翘曲会随着回流焊温度的升高而增大,回流焊升降温速率较快同样会导致严重的热翘曲。实验结果与仿真结果高度一致,进而验证了仿真模型的准确性和有效性。采用实验结合有限元分析的方法为改善集成电路热翘曲提供了参考。

大尺寸有机基板的材料设计与封装翘曲控制

倒装芯片球栅阵列(FCBGA)基板具有尺寸大、层数多等特点,可以满足大尺寸芯片超高速运算的需求。随着芯片尺寸的增大,有机基板的翘曲问题变得更加突出,因此,需要对有机基板材料在热膨胀系数(CTE)、模量、树脂收缩率、应力控制等方面进行升级。对FCBGA基板使用的大尺寸有机基板材料进行研究,重点研究其关键性能参数,如CTE、模量和树脂收缩率等,进一步探讨了对树脂基体、无机填料和玻璃纤维布等材料的选择以及生产制造过程中的应力控制,并对大尺寸有机基板材料技术的发展趋势进行了展望。

掺杂种类对磷化铟晶片切割损伤层及翘曲度的影响

研究了掺杂对磷化铟(InP)单晶切割损伤层及翘曲度的影响。使用化学腐蚀法研究了相同切割工艺条件下不同掺杂晶片的损伤层厚度的差别,得到了切割损伤层厚度以及在相同腐蚀条件下不同掺杂晶片的本征腐蚀速率。4种InP晶片的本征腐蚀速率排序为掺S晶片>掺Fe晶片>非掺杂晶片>掺Zn晶片。研究晶片损伤层对翘曲度的影响时应结合晶体各向异性。利用Stoney公式,结合InP单晶加工应力特性,分析了损伤层厚度与晶圆翘曲度的关系。研究结果表明,由于[001]晶片表面各区域的加工性能呈现出较强的各向异性,造成表面损伤状态也呈现同样的规律,导致切割片呈现“马鞍”状。最后提出了如降低加工应力、优化腐蚀方案等降低InP切割片翘曲度的有效途径。

胶原蛋白及自退火行为对电解铜箔翘曲性能的影响

电解铜箔在生产过程中极易出现铜箔翘曲度高等问题,严重影响铜箔后续加工和装配,是电解铜箔的关键共性难题之一。本文以不同浓度的胶原蛋白作为添加剂,研究了胶原蛋白对电解铜箔翘曲度的影响,并探讨了其作用机制。结果表明,胶原蛋白的最佳加入量为10 mg/L,此时铜箔的抗拉强度达到382.5 MPa,翘曲度大幅降低至16 mm。随着胶原蛋白浓度的升高,铜箔的抗拉强度不断增加。胶原蛋白通过促进铜箔形成(220)Cu晶面择优取向,降低铜箔表面粗糙度,显著改善铜箔的翘曲度。加入10 mg/L胶原蛋白,铜箔的(220)Cu晶面的织构系数(Tc)增加到57.8%,毛面粗糙度Rz降低到1.9μm,翘曲度降至16 mm。由于胶原蛋白残留在铜箔内部,导致铜箔发生自退火行为。铜箔通过自退火释放了部分残余应力,使得铜箔的翘曲度进一步降低至9 mm。因此,胶原蛋白是一种有效降低铜箔翘曲度的添加剂,并且能够通过之后的自退火行为,进一步降低铜箔的翘曲度。

FDM成型工艺对PEEK/CGF复合材料翘曲变形的影响

为降低连续玻璃纤维增强聚醚醚酮复合材料增材制造样件的翘曲变形,优化增材制造基础工艺参数,通过单因素试验、Plackett-Burman Design试验与Box-Behnken Design试验,研究了打印过程中的热效应,即保温舱温度、层厚、成型平台温度、打印速度等工艺参数对连续玻璃纤维增强聚醚醚酮复合材料样件翘曲变形的影响规律,得出如下结论:研究发现打印工艺对翘曲度的影响程度是不同的,影响程度依次为B(层厚)>C(成型平台温度)>A(保温舱温度)。研究发现打印工艺参数之间是会对翘曲变形产生交互作用的,并且影响程度也较为显著(PB析因试验中大于t值),即B>C>A>AB>BC>D(打印速度)>BD。研究发现喷头温度440℃,成型平台温度100℃,保温舱温度90℃,层厚0.3 mm,道间距为0.5 mm,打印速度2 mm/s时,翘曲度可达到0.23%。

基于Kriging代理模型及改进PSO的变模温注塑成型翘曲变形优化

为提升变模温注塑成型的产品质量,提高优化效率,将翘曲变形作为优化目标,模具温度、保压压力、熔体温度、保压时间、冷却时间等工艺参数作为变量因素,采用Moldflow模拟变量因素对优化目标的影响,通过最优拉丁超立方试验设计选出试验样本,建立Kriging代理模型,并且,检测代理模型拟合精度。采用改进PSO算法,得到最优翘曲模型预测值及最佳工艺参数组合。对比改进后的PSO与标准PSO,平均迭代次数、迭代时间约降低了45%,最优适应度、平均适应度、最差适应度、局部最优解及未实现收敛等参数均得到提升。通过实验验证可知,与优化前翘曲值(1.293 mm)相比,优化后翘曲值(0.7512 mm)降低了41.9%,误差为4.84%。结果表明,基于Kriging代理模型及改进PSO能有效地优化变模温成型工艺,降低了翘曲变形量,对于生产应用有指导意义。

差温轧制6063/7072铝合金复合板有限元模拟及翘曲影响因素

高能量密度动力电池的发展对液冷板提出了高安全、高性能制造要求,针对传统“冲压-钎焊”工艺焊合可靠性低、界面抗冲击性差等缺点,本工作提出“差温轧制-吹胀”新工艺以制备结合良好、界面质量高的6063/7072铝合金液冷板。但异质金属的轧制易形成翘曲缺陷,导致后续吹胀工艺无法正常进行,因此亟需研究轧制液冷板的翘曲机理及其影响规律。本工作通过ANSYS/LS-DYNA有限元仿真和实验相结合的方式,研究了其差温轧制过程中的翘曲行为及其机理,分析了工艺参数对翘曲曲率的影响规律。结果表明:轧制方向的应力不协调导致6063铝合金板相对7072铝合金板需产生更大形变以达到应力平衡,轧制方向的应力差可以用来表征6063/7072铝合金液冷板的翘曲情况;提高轧制压下率、增大轧制温度差以及减小6063铝合金板厚度比例可有效降低液冷板的翘曲曲率,从而提高液冷板成形精度;实验与仿真的翘曲曲率相对误差小于5.58%,表明本研究的有限元模型准确可靠;通过差温轧制实验得到了6063/7072铝合金复合板,表明差温轧制复合板技术方案可行,为液冷板的高性能制造提供了有效途径。

充电桩装饰盖的成型设计和多目标优化

针对交流装饰盖产品的开发,进行注塑成型仿真设计。首先,识别出装饰盖存在注塑压力和变形翘曲量过大的问题;其次,从结构、浇口位置、工艺参数多种方式,逐步对压力和变形翘曲实行多目标优化;最后,试模验证注塑优化方案的可行性。研究得到:由于主壁厚1.5 mm,过薄,导致压力和翘曲变形问题,调整主壁厚到3 mm,注塑压力可以成型,同时变形值变小;继续调整浇口位置,变形值进一步降低,最后优化工艺参数,得到总变形值为2.02 mm,达到装配要求。本研究方法为交流充电桩注塑成型的优化提供了一定的指导。

三维集成堆叠结构的晶圆级翘曲仿真及应用

随着先进电子封装产品对低成本和高性能的需求不断提高,三维集成技术以其传输速度快、功耗低、封装尺寸小、系统集成度高等优势,逐渐成为一个主流研发方向。三维集成封装通常采用晶圆级制造技术,由于半导体制造工艺及三维结构设计的复杂性,加之晶圆尺寸增大、厚度减小等发展趋势,使得有效控制晶圆翘曲以保证产品良率和可靠性面临着更大挑战。针对12英寸晶圆的典型三维集成结构,采用有限元仿真分析方法,研究多层薄膜堆叠产生的晶圆翘曲。对临时键合、晶圆减薄、晶圆键合及解键合等不同晶圆制造工艺中的翘曲变化进行了模拟计算,并选取关键工艺及设计参数进行评估与优化。通过对比实际产品的测量结果验证了仿真模型的合理性,运用仿真方法为产品设计提供了参数选择的指导依据。

基于FCBGA封装应用的有机基板翘曲研究

有机基板作为IC封装的重要载体,其制造材料的特性对封装工艺的稳定性及可靠性有重要影响。针对倒装芯片球栅阵列(FCBGA)有机基板在再流焊过程中的翘曲问题,使用热形变测试仪研究了不同尺寸和芯板厚度的有机基板在再流焊过程中的共面性及形变情况,研究FCBGA有机基板的翘曲行为。针对大尺寸FCBGA有机基板在再流焊过程中的翘曲问题,从脱湿、夹持载具以及再流焊曲线优化等方面提出改善措施,为FCBGA有机基板的封装应用提供参考。