PCB拼板问题相关研究综述

印刷线路板或印制电路板(Printed Circuit Board,PCB)是工业上重要的电子器件和现代电子信息设备中不可或缺的基础部件,从手机到大型航天装备,几乎所有的电子产品都需要用到PCB电路板。随着工业4.0大数据时代的到来,云计算、物联网的演变与普及,作为"电子产品之母"的PCB产业将成为整个电子产业链中坚实的基础力量。我国PCB生产企业目前主要采用Genesis或CAM350,两者都是由国外开发的软件产品,国内还没有同类产品。基于此,对PCB拼板问题的相关研究进行综述,以此为后续开发奠定基础。

Modeling of Micropores Drilling Force for Printed Circuit Board Micro-holes Based on Energy Method

The quality of printed circuit board(PCB)micro-hole processing directly determines the stability of the inner and outer circuit connections.Micro-hole drilling technology is a typical method for PCB micro-hole processing.The problem of optimal control of its drilling force is one of the main factors affecting the quality of micro-hole machining.To address this problem,the thrust forces and torques in PCB drilling were first modeled and analyzed,and the corresponding prediction models were established.The drilling force analysis was carried out through the micro-hole drilling experiment,the specific cutting energy under different feed rates was calculated,the influence of the size effect was clarified,and the accuracy of the prediction model was verified.The result shows that during the drilling of glass fiber cloth,changes in the material removal mechanism are induced as the feed per revolution is varied.When the feed per revolution is less than the tool edge radius,the glass fiber is not cut by the main cutting edge,but is crushed and broken.When the feed per revolution is greater than the radius of the tool edge,the glass fiber is cut by the main cutting edge.At the same time,the established analytical model can accurately reflect the influence of the size effect on the drilling torque in PCB micro-hole drilling,and the error is within 10%.This method has certain practical application value in controlling PCB micro hole processing quality.

黑龙江省主要排放源非故意产生多氯联苯的时空异质性分布特征

在确定黑龙江省非故意产生多氯联苯(UP-PCBs)主要排放源为水泥行业、钢铁烧结、炼焦工业及热电站(煤)的基础上,利用1949—2014年黑龙江省4类主要排放源UP-PCBs的排放量为111 538 g,约占全国总排放量的0.86%。UP-PCBs的总排放量与GDP值呈显著相关(R=0.980,P=0.000)。水泥行业、钢铁烧结及焦炭生产UP-PCBs排放均呈现由缓慢增加到快速增长,达到峰值后随之降低的波动趋势。2001—2014年UP-PCBs排放呈现较大的空间波动性,排放量增长率最低的城市为鹤岗(呈现负增长)、伊春、牡丹江和七台河;哈尔滨、齐齐哈尔、牡丹江、大庆和绥化UP-PCBs排放对总排放量的贡献率超过5%。

DEM:Deep Entity Matching Across Heterogeneous Information Networks

Heterogeneous information networks,which consist of multi-typed vertices representing objects and multi-typed edges representing relations between objects,are ubiquitous in the real world.In this paper,we study the problem of entity matching for heterogeneous information networks based on distributed network embedding and multi-layer perceptron with a highway network,and we propose a new method named DEM short for Deep Entity Matching.In contrast to the traditional entity matching methods,DEM utilizes the multi-layer perceptron with a highway network to explore the hidden relations to improve the performance of matching.Importantly,we incorporate DEM with the network embedding methodology,enabling highly efficient computing in a vectorized manner.DEM's generic modeling of both the network structure and the entity attributes enables it to model various heterogeneous information networks flexibly.To illustrate its functionality,we apply the DEM algorithm to two real-world entity matching applications:user linkage under the social network analysis scenario that predicts the same or matched users in different social platforms and record linkage that predicts the same or matched records in different citation networks.Extensive experiments on real-world datasets demonstrate DEM's effectiveness and rationality.

溶剂调控Pd/C催化多氯联苯高效加氢脱氯

采用沉积沉淀法制备了5%Pd/C催化剂,研究了溶剂体系对其催化4-氯联苯(4-CBP)加氢脱氯的影响,建立了正丁醇-水两相溶剂体系,实现了高浓度电容器油(主要为多氯联苯(PCBs))的高效加氢脱氯降解.结果表明,相对比非质子溶剂,醇类等质子溶剂对加氢脱氯反应更加有利.水的加入对异丙醇-水均相溶剂和有机-水两相溶剂中Pd/C催化4-CBP加氢脱氯均有明显的促进作用,而且在正丁醇-水(1:3,V/V)两相溶剂体系中可以在90min内实现4-CBP加氢脱氯的完全转化,而且催化剂可以重复使用8次以上.在该溶剂体系中,10g/L的含PCBs电容器油在Pd/C催化下可以在360min内完全加氢脱氯生成联苯.

异质多元多层印制电路板精密孔机械加工

孔是实现印制电路板层间互联及电子元器件装配的核心组成单元,机械钻孔是印制电路板制孔的主要方法。要在印制电路板上进行高密集度孔群的连续可靠、高质量、高一致性和高稳定性加工非常困难,涉及的异质多元多层复合材料机械加工理论复杂,也对加工刀具、加工技术提出了严峻挑战。从机械加工的角度归纳了典型印制电路板分类、组成结构与热力学特性,并提出其机械钻孔加工面临的难点;从材料变形与断裂、钻削热、钻削力与扭矩、孔创成机理、刀具失效机制五个方面,总结了典型印制电路板钻削理论的最新进展,综述了印制电路板用钻头设计、钻孔加工工艺和钻削过程检测技术的研究现状,从印制电路板微孔钻削加工理论、微细刀具优化设计、低温介质辅助钻削加工与孔质量无损检测方面指出了现有研究存在的问题,并结合新一代高端印制电路板发展趋势与孔制造需求,提出了未来印制电路板孔加工研究应重点关注的方向。