A Study of Solder Paste Rheology for The Alternative Assembly and Reflow Technology (AART) Process

1998 ◽  
Vol 515 ◽  
Author(s):  
S.T. Murthy ◽  
D. Manessis ◽  
K. Srihari ◽  
G.R. Westby
Keyword(s):  
Yield Stress ◽  
Printed Circuit Board ◽  
Shear Thinning ◽  
Circuit Board ◽  
Print Quality ◽  
Solder Paste ◽  
Assembly Process ◽  
Pcb Assembly ◽  
Plated Through Hole ◽  
Through Hole

ABSTRACTSolder paste performance related properties such as stencil print quality, viscosity, thixotropy, and slump resistance are of great importance in the pre-reflow stages of the electronics assembly process. This paper focuses on the study of the rheological behavior of solder paste and its correlation to process performance during the various steps of the Alternative Assembly and Reflow Technology (AART) process. This technology aims to integrate the Printed Circuit board (PCB) assembly process for both through hole and surface mount components. Four solder pastes were considered in this study and their rheological characteristics were identified through flow and oscillation tests. The oscillation tests provided the linear viscoelastic characteristics of solder paste whereas the flow tests revealed information on the yield stress as well as the degree of shear-thinning and thixotropy of the solder paste. Pastes with high elastic properties and yield stress exhibited good hot slump resistance. Furthermore, extensive shear thinning of the paste facilitated the filling of the Plated-Through-Hole (PTH) sites. Recommendations are provided for tailoring the properties of a solder paste to meet the needs of the AART process.

Thermal Model of Printed Circuit Board Plated-Through Hole under One-Sided Heating Conditions

2021 ◽  
Vol 26 (5) ◽  
pp. 426-431
Author(s):  
V.A. Sergeev ◽  
◽  
A.M. Khodakov ◽  
M.Yu. Salnikov ◽  
◽  
...  
Keyword(s):  
Quality Control ◽  
Thermal Resistance ◽  
Thermal Model ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Thermal Models ◽  
Printed Circuit ◽  
Plated Through Hole ◽  
Through Hole

Thermal methods of quality control of the plated-through hole (PTH) of printed circuit board (PCB) are based on thermal models. However, known thermal models of PTH take no account of heat transfer to PCB material thus not allowing for PTH heat characteristic tying up with adhesion quality. In this work, an axisymmetric thermal model of a single-layer PCB PTH under one-sided heating conditions is considered. It was shown that the ratio of the temperature increments of the upper (heated) and lower end of the PTH in the considered range of heating power does not depend on the power level. A linear thermal equivalent scheme of the PTH has been proposed, which includes the longitudinal thermal resistance of the PTH metallization, de-termined by the parameters and quality of the metallization layer, the thermal resistance, which determines the convection heat exchange between the ends of the PTH with the adjacent PCB surface and the environment, and the thermal resistance of the area of the PCB material adjacent to the PTH, depending on the quality of the metallization adhesion and the PCB dielectric. Thermal equivalent circuit parameters determined by the ratio of the temperature increment of the upper and lower ends of the PTH and their difference can serve as the basis for the development of a nondestructive inspection procedure for PTH quality control by way of its unilateral heating, for example, by a laser beam.

Modeling of Errors Counting System for PCB Soldered in the Wave Soldering Technology

2014 ◽  
Vol 874 ◽  
pp. 139-143 ◽  
Author(s):  
Jacek Pietraszek ◽  
Aneta Gądek-Moszczak ◽  
Tomasz Toruński
Keyword(s):  
Quality Assurance ◽  
Experimental Design ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Counting System ◽  
Printed Circuit ◽  
Pcb Assembly ◽  
Wave Soldering ◽  
Soldering Technology ◽  
Through Hole

PartnerTech provides printed circuit board (PCB) assembly on request. Wired elements are assembled in through-hole technology and soldered on the wave soldering machine. The PCB with inserted elements is passed across the pumped wave of melted solder. Typically this process is accompanied by some class of defects like cracks, cavities, wrong solder thickness and poor conductor. In PartnerTech Ltd. another type of defects was observed: dispersion of small droplets of solder around holes. Quality assurance department plans to optimize the process in order to reduce the number of defects. In the first stage, it was necessary to develop a methodology for counting defects. This paper presents experimental design and analysis related to this project.

Fatigue Analysis of a Ceramic Pin Grid Array Soldered to an Orthotropic Epoxy Substrate

1991 ◽  
Vol 113 (2) ◽  
pp. 138-148 ◽  
Author(s):  
J. Lau ◽  
R. Subrahmanyan ◽  
D. Rice ◽  
S. Erasmus ◽  
C. Li
Keyword(s):  
Thermal Expansion ◽  
Solder Joint ◽  
Normal Stress ◽  
Printed Circuit Board ◽  
Thermal Stresses ◽  
Circuit Board ◽  
Thermal Expansion Mismatch ◽  
Stress Strain ◽  
Plated Through Hole ◽  
Through Hole

Thermal stresses and strains in the solder joints and plated-through-hole (PTH) copper pads/barrels of a pin-grid array (PGA) assembly under thermal cycling conditions have been determined in the present study. There are two major systems of thermal stresses/strains acting at the solder joint and copper. One is the transverse shear and vertical normal stress/strain due to the local thermal expansion mismatch between the pin, solder, copper, and FR-4. The other is the horizontal normal stress/strain due to the global thermal expansion mismatch between the ceramic PGA and the FR-4 printed circuit board (PCB). The effects of the local thermal expansion mismatch on the reliability of solder joint and PTH copper have been determined using a 3-D orthotropic-elastoplastic finite element method. The effects of the global thermal expansion mismatch on the reliability of solder joint and PTH copper have been determined by fatigue experiments. Fatigue life of the solder joint and PTH copper was then estimated based on the calculated strains and the fatigue data on solders and coppers.

TEM Analysis of Printed Circuit Board Copper Foil

1980 ◽  
Vol 38 ◽  
pp. 408-409
Author(s):  
Ron Anderson ◽  
Roger Wild
Keyword(s):  
Copper Foil ◽  
Printed Circuit Board ◽  
Stress Test ◽  
Thermal Exposure ◽  
Circuit Board ◽  
Tem Analysis ◽  
Plated Through Hole ◽  
Columnar Grain ◽  
Test Requirements ◽  
Through Hole

Approximately two years ago, electro-deposited (ED) copper foil cracking was noticed when testing relatively high density, highly stressed multilayer boards (MLBs) to the rigid 55()°F thermal stress test requirements of MIL-P-55640 and eventually MIL.-P-551 IOC. This ED copper foil cracking is basically caused by severe plated through hole (PTH) bending forces caused by the large difference in thermal expansions between the copper PTH barrel and the epoxy glass resin within the multilayer board at high soldering lemperatures. The severity of the copper foil cracking would be dependent on the basic thermal mismatch of MLB materials; the severity of thermal exposure; the specific design impacts; and the mechanical properties of the copper foil. Copper foil cracks develop circumferentially around the PTH barrel within the relatively weak columnar grain boundaries of the ED copper foil. Generally, cracks occur quite close (within 2 mils) of the PTH barrel wall with cracking or fracturing being more dominant on the first and last internal foil layers within the board.

Stereoimaging Determination of Strains in Surface Mounted Components and Plated Through Holes Resulting from Thermal Cycung

1991 ◽  
Vol 226 ◽  
Author(s):  
David L. Davidson
Keyword(s):  
Printed Circuit Board ◽  
High Spatial Resolution ◽  
Circuit Board ◽  
Depth Of Field ◽  
Scanning Microscope ◽  
Printed Circuit ◽  
Plated Through Hole ◽  
Microelectronic Components ◽  
Through Hole

AbstractThe experimental mechanics of microelectronics components requires high spatial resolution measurements that are best obtained by using the scanning microscope because of the high spacial resolution and depth of field obtained using this instrument. This paper describes how measurements made from photographs taken in the scanning electron microscope have been used successfully to determine the strains which develop due to differences in coefficient of thermal between various parts of microelectronic components. Results are presented for thermal strains in the solder joints of a surface mounted component and in a printed circuit board plated through hole.

scholarly journals An intelligent approach for improving printed circuit board assembly process performance in smart manufacturing

2020 ◽  
Vol 12 ◽  
pp. 184797902094618
Author(s):  
Vincent WC Fung ◽  
Kam Chuen Yung
Keyword(s):  
Printed Circuit Board ◽  
Circuit Board ◽  
Smart Manufacturing ◽  
Process Performance ◽  
Solder Paste ◽  
Assembly Process ◽  
Printed Circuit Board Assembly ◽  
Printed Circuit ◽  
Circuit Board Assembly ◽  
Solder Paste Printing

The process of printed circuit board assembly (PCBA) involves several machines, such as a stencil printer, placement machine and reflow oven, to solder and assemble electronic components onto printed circuit boards (PCBs). In the production flow, some failure prevention mechanisms are deployed to ensure the designated quality of PCBA, including solder paste inspection (SPI), automated optical inspection (AOI) and in-circuit testing (ICT). However, such methods to locate the failures are reactive in nature, which may create waste and require additional effort to be spent re-manufacturing and inspecting the PCBs. Worse still, the process performance of the assembly process cannot be guaranteed at a high level. Therefore, there is a need to improve the performance of the PCBA process. To address the aforementioned challenges in the PCBA process, an intelligent assembly process improvement system (IAPIS) is proposed, which integrates the k-means clustering method and multi-response Taguchi method to formulate a pro-active approach to investigate and manage the process performance. The critical process parameters are first identified by means of k-means clustering and the selected parameters are then used to formulate a set of experimental studies by using the multi-response Taguchi method to optimize the performance of the assembly process. To validate the proposed system, a case study of an electronics manufacturer in the solder paste printing process was conducted. The contributions of this study are two-fold: (i) pressure, blade angle and speed are identified as the critical factors in the solder paste printing process; and (ii) a significant improvement in the yield performance of PCBA can be achieved as a component in the smart manufacturing.

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