A Repeatable and Reliable Rework Process for Lead-Free Fine Pitch BGA’s

2005 ◽  
Author(s):  
Deepak Manjunath ◽  
Satyanarayan Iyer ◽  
Shawn Eckel ◽  
Purushothaman Damodaran ◽  
Krishnaswami Srihari
Keyword(s):  
Primary Objective ◽  
Lead Free ◽  
Process Window ◽  
Solder Paste ◽  
Ball Grid Arrays ◽  
Joint Reliability ◽  
Fine Pitch ◽  
Pros And Cons ◽  
Free Solder ◽  
Rework Process

Fine pitch leadless components, such as Ball Grid Arrays (BGAs) and Chip-Scale Packages (CSPs), are increasingly used in modern day circuitry to aid miniaturization. Assembling these surface mount components using lead-free solder pastes has been a subject of interest for the past several years. Reworking a BGA is complicated as the solder joints are hidden underneath the component. The process window available for the rework process is very narrow and there are number of other critical factors, which complicate and affect the repeatability of the rework process. Consequently, the primary objective of this research endeavor is to develop a reliable and a repeatable process to rework lead-free fine pitch BGAs. The process steps to rework a BGA are component removal, site redressing, solder paste/flux deposition, component replacement and reflow. This experimental study evaluates a number of alternatives for several rework process steps during the course of developing a reliable and repeatable rework process. Two alternatives for site redressing namely, (i) copper wick with soldering iron, and (ii) vacuum de-soldering methods are evaluated. Similarly the application of solder paste versus gel flux is compared. A localized reflow method for replacing the component at the SRT machine is developed and it is compared with forced convection in reflow oven. The pros and cons of using the two reflow methods and the effect of multiple reflows on solder joint reliability is discussed in the paper. A reliability study was conducted on the samples and the results are presented to compare the various alternatives.

Super Fine Lead-Free Solder Powder for Fine Pitch Bump Applications

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 001016-001038
Author(s):  
Ryuji Uesugi ◽  
Hironori Uno ◽  
Masayuki Ishikawa ◽  
Akihiro Masuda ◽  
Hiroki Muraoka ◽  
...  
Keyword(s):  
Chemical Reduction ◽  
Fine Powder ◽  
Lead Free ◽  
High Yield ◽  
Solder Paste ◽  
Fine Pitch ◽  
Solder Bumps ◽  
Wet Chemical ◽  
Free Solder ◽  
Near Future

We have successfully developed super fine lead-free and low alpha solder powder, which contains more than two elements by the method of wet chemical reduction. The size (D50) of super fine powder is around 2–3 micrometer to meet finer pitch assembly in the near future. This new method made it available to synthesize various compositions of solder powder like Sn-Ag, Sn-Cu, Sn-Ag-Cu, etc. Also, this method achieves very high yield compared to a gas atomization method. A solder paste for printing method composed of the fine solder powder has a superior printing ability because of the unique powder shape. The powder shows anisotropic shape, and it can make printed figure excellent after printing without bridge and coplanarity issues for finer pitch applications. With our super fine solder paste, we will be ready for <100um pitch of solder bumps which will come in a few years. Furthermore, the super fine powder is applied to the Cu pad pre-coat. The solder paste for pre-coat composed of the super fine powder shows an excellent coverage and solders flatness on the outer pad after reflow.

Influence of assembly parameters on lead-free solder joints reliability in Package-on-Package (PoP) technology

2015 ◽  
Vol 27 (3) ◽  
pp. 98-102 ◽  
Author(s):  
Janusz Sitek ◽  
Wojciech Stęplewski ◽  
Kamil Janeczek ◽  
Marek Kościelski ◽  
Krzysztof Lipiec ◽  
...  
Keyword(s):  
Solder Joints ◽  
Accelerated Aging ◽  
Lead Free ◽  
Process Window ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Materials Selection ◽  
Content Type ◽  
Free Solder ◽  
Component Assembly

Purpose – The purpose of this paper is to evaluate the influence of assembly parameters on lead-free solder joints reliability in Package-on-Package (PoP) Technology and demonstrate factors important for this issue. Design/methodology/approach – Two types of soldering materials and three different assembly procedures were used for assembly of PoP system. The reliability properties of assembled PoP systems were investigated using accelerated aging and periodic resistance measurements of daisy-chain solder joints systems. The purpose of such approach was to determine which soldering material (flux or solder paste) as well as which assembly process parameter (dipping depth of upper component in soldering material), would provide better reliability properties of the solder joints in the PoP system. Findings – It was stated that both selected flux and solder paste dedicated to assembly of PoP systems can be utilized in soldering of PoP applications. More reliable PoP systems applications require larger attention regarding materials selection and assembly parameters. It is recommended 50 per cent dipping depth of ball’s height into soldering material during upper PoP component assembly for more reliable applications. For less demanding PoP systems, the process window from 30 up to 70 per cent is acceptable. All observed failures after thermal shocks occurred in upper PoP components. Originality/value – This paper explains how materials and assembly parameters have influence on lead-free solder joints reliability in PoP systems. Especially, influence of process window for dipping procedure of upper components balls into soldering material was presented.

scholarly journals Eco-Friendly Lead-Free Solder Paste Printing via Laser-Induced Forward Transfer for the Assembly of Ultra-Fine Pitch Electronic Components

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3353
Author(s):  
Marina Makrygianni ◽  
Filimon Zacharatos ◽  
Kostas Andritsos ◽  
Ioannis Theodorakos ◽  
Dimitris Reppas ◽  
...  
Keyword(s):  
High Resolution ◽  
Form Factors ◽  
Circuit Board ◽  
Lead Free ◽  
Process Conditions ◽  
Solder Paste ◽  
Electronic Components ◽  
Successful Operation ◽  
Fine Pitch ◽  
Forward Transfer

Current challenges in printed circuit board (PCB) assembly require high-resolution deposition of ultra-fine pitch components (<0.3 mm and <60 μm respectively), high throughput and compatibility with flexible substrates, which are poorly met by the conventional deposition techniques (e.g., stencil printing). Laser-Induced Forward Transfer (LIFT) constitutes an excellent alternative for assembly of electronic components: it is fully compatible with lead-free soldering materials and offers high-resolution printing of solder paste bumps (<60 μm) and throughput (up to 10,000 pads/s). In this work, the laser-process conditions which allow control over the transfer of solder paste bumps and arrays, with form factors in line with the features of fine pitch PCBs, are investigated. The study of solder paste as a function of donor/receiver gap confirmed that controllable printing of bumps containing many microparticles is feasible for a gap < 100 μm from a donor layer thickness set at 100 and 150 μm. The transfer of solder bumps with resolution < 100 μm and solder micropatterns on different substrates, including PCB and silver pads, have been achieved. Finally, the successful operation of a LED interconnected to a pin connector bonded to a laser-printed solder micro-pattern was demonstrated.

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

Study of a Low Cost Reballing of BGA Method with Lead-Free Solder Paste

2019 ◽  
Vol 14 (1) ◽  
pp. 651-657
Author(s):  
Talita Mazon ◽  
Guilherme E. Prevedel ◽  
Egont A. Schenkel ◽  
Marcio T. Biasoli
Keyword(s):  
Low Cost ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Free Solder
Sign in / Sign up

Export Citation Format

Share Document