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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Modeling of digital manufacturing of electronics production and product quality assurance</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>G I Korshunov</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>A A Petrushevskaya</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Ciberphisic systems and control high school, Peter the Great St. Petersburg Polytechnic University (SPB STU)</institution>
          ,
          <addr-line>29, Polytechnicheskaya St., Saint-Peterburg, Russian Federation, 195251</addr-line>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>State Autonomous Educational Institution of Higher Education "Saint-Petersburg State University of Aerospace Instrumentation" (SUAI)</institution>
          ,
          <addr-line>ul. Bolshaya Morskaya, 67, lit. A, St. Petersburg, Russian Federation, 190000</addr-line>
        </aff>
      </contrib-group>
      <fpage>150</fpage>
      <lpage>159</lpage>
      <abstract>
        <p>Intensive development of digital production in accordance with the concept of "Industry 4.0" is the most important direction of innovative development. The main elements of the concept are being introduced into the production of electronic products in demand in all spheres of human activity. To create new objects that represent the concept of "Industry 4.0", it is necessary to introduce technological innovations in the electronics industry. This is achieved by solving urgent problems of analyzing the system properties of the means of production and ensuring product quality. Therefore, the purpose of the article is to ensure the quality of electronic products on the basis models and techniques for analyzing the means and processes of electronics production. To achieve the goal, the development of digital production is considered within the framework of a structural, functional and information description. The resulted modeling results of stages a manufacture life cycle have allowed to estimate reached level of production quality at perfection of subsystems of automatic installation of printedcircuit boards.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The existing technologies for the automatic installation of printed circuit boards are constantly
evolving, but the equipment remains composition consistent with the basic structure. Continuous
improvement and miniaturization of the electronic component base puts forward new requirements for
equipment. Quality assurance is achieved by improving the characteristics of equipment, but the
influence the "human factor" and the lack of consideration the mutual influence of the parts the
production line remain factors of uncertainty in the production process.</p>
      <p>Intellectual solutions in the field of inter-machine communications (M2M) play a special role in the
development of IoT. This is the largest segment of the IoT market, connected with the integration of
Internet things and "small" ad hoc IoT with larger systems. Introducing the elements of the "Industry
4.0" concept has opened new opportunities for ensuring the quality of electronic products both on the
basis of more and more complete "digitization" of production, and at transition to a full digital life
cycle of production.</p>
      <p>In article on the basis of world tendencies and own experience it is offered to introduce elements of
the concept "Industry 4.0" step by step, on the basis of the analysis of means and processes of
electronics production within the framework of structural, functional and information description.
Solving the problems of system analysis and developing models for improving production efficiency
and modeling processes created the necessary methodological basis for ensuring the quality of
products.
2. Structures of the technological line of automatic assembly of printed circuit boards
The necessary functional organization and the possibility of its building up with technological
innovations are the basis for choosing the option of the structure of the automatic circuit board
assembly line, presented as a system. Technical re-equipment is a key factor for the formation of more
competitive production. It is aimed at improving the consumer properties of the produced products
that make up its quality, as well as increasing the technological flexibility of the production process.
The process of re-equipment of production is continuous, and therefore, after analyzing the results of
introducing technological innovation, a transition to the stage of monitoring the state of production
takes place. Thus, the process of technical re-equipment is cyclical, beginning with the discovery of a
discrepancy between the actual parameters of the facility (fixed productive assets), new requirements
and norms, technical conditions and quality indicators determined by the market, and ending with the
decision to develop and implement a specific technical re-equipment project.</p>
      <p>
        Here it is appropriate to use the idea of creating a new product on the basis structure that is not new
and is reduced to the tasks of forming options and choosing the optimal ones. In [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], the intuitive
"structural" approach to creating a new product is presented as the selection of some basic minimum
set of tools for the subsequent enhancement of functionality in order to perform increasingly complex
tasks.
      </p>
      <p>
        The basic structures are functionally necessary (FNS) and functionally-sufficient (FSS) structures.
Definition [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. The structure of the SFS is designated as a functionally necessary structure (SFN),
designed to perform a defined class of the same purposes, functions, tasks, in which there is no kind of
redundancy, and the minimum values of quality indicators from a given set forming an integral quality
criterion (IQC) are achieved:
      </p>
      <p>IQC:= Qi, SFNSS; QiFNS=QiFNS: i, QiFNSQi.</p>
      <p>
        Functionally-sufficient structures (FDS) are characterized by the presence of some redundancy,
which is permissible within the limits of given constraints, in this connection, the study of structures
based on the coefficients of significance of its constituent elements, presented in [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], acquires great
importance.
      </p>
      <p>
        The [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] standards and other known examples [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] use a line that meets the requirements of IPC and
SMEMA for electrical and mechanical compatibility as a functionally necessary structure.
Modern industrial technologies require the creation of a competitive basic hardware structure, which is
an integration platform for the Internet of things and ensures the acquisition, storage, processing,
visualization of data and their integration at all levels of the enterprise. The M2M platform of the
electronics manufacturing enterprise will contain universal device drivers on all production facilities
of the enterprise, allowing to connect any industrial or custom Iot device under the encoded
connection of "foggy computing". The use of low-bandwidth channels will ensure the security of the
transmission of commercial secrets of the enterprise.
      </p>
      <p>To create an integration platform for the Internet of things, it is necessary to build an ontology of
the enterprise and databases, which are the detailing of work at all stages of the enterprise's life cycle
from the stage of purchasing components to shipping to customers, and using the Design for
Manufacturing (DFM) concept to take a set of measures to define possible risks and problematic parts
that could adversely affect the production process. Using the tools of the DFM will allow to ensure the
elimination of inconsistencies in accordance with the requirements of IPC standards during the
implementation of the phase. One of the most important tasks for detailing processes and creating
knowledge bases of an enterprise is the disclosure of uncertainties. However, the correctly executed
modeling process does not remove the uncertainty, but contributes to the understanding and
management of complex risks, as well as the analysis of their consequences.</p>
      <sec id="sec-1-1">
        <title>Technological innovation М2М</title>
      </sec>
      <sec id="sec-1-2">
        <title>Database</title>
        <p>Paste
(SPI)
Parametric model of the
process, means of storage
and processing of large
data, accessible user
interface.</p>
        <p>Provides both
twodimensional and
threedimensional control of
paste application.</p>
      </sec>
      <sec id="sec-1-3">
        <title>Provides the storage of</title>
        <p>models of standards, the
process of identifying
defects and minimizing the
number of false failures.
Allows you to store all
found defects and confirm
them before changing the
work program. If there are
conflicting monitoring
results, the disputable
parameters are displayed on
the screen.</p>
        <p>The knowledge base
integrates databases, data
on technological operations
and materials, allows
finding the necessary
information. Contains a
systematic list of defects
for different stages of
production, an interface for
entering new data by the
user.</p>
      </sec>
      <sec id="sec-1-4">
        <title>Device Drivers, Internet of</title>
        <p>Things.
3D-inspection is realized due
to the proven method of
projecting strips, as a result
of which a three-dimensional
image is formed. Recognition
of three-dimensional images
occurs with further
mathematical processing.
Digital model of the
standard.</p>
      </sec>
      <sec id="sec-1-5">
        <title>Means for presenting specific</title>
        <p>and fuzzy knowledge in a
given domain, ontology.</p>
        <p>The introduction of technological innovations provides new functional and information support
provided by the concept "Industry 4.0" using the elements of the concept of M2M, DFM, BOM,
IDidentifiers. Examples of functional and information support of technological innovations are given in
table 1.</p>
        <p>The structures of the subsystems, including M2M and the knowledge base, are shown in fig.
Presented basic structure of interaction of elements of the concept "Industry 4.0".</p>
      </sec>
      <sec id="sec-1-6">
        <title>Quality assurance</title>
      </sec>
      <sec id="sec-1-7">
        <title>Correction of technologies based on quality control.</title>
        <p>Correction of
materials and
finalization of
products of
technologies
based on quality
control.</p>
      </sec>
      <sec id="sec-1-8">
        <title>Ensures</title>
        <p>compliance with
quality standards.
Continuous
quality
improvement
based on
parametric
model,
descriptions
under
uncertainty.</p>
        <p>a
fuzzy
or</p>
        <sec id="sec-1-8-1">
          <title>Identifier (ID)</title>
        </sec>
        <sec id="sec-1-8-2">
          <title>Identifier (ID)</title>
        </sec>
        <sec id="sec-1-8-3">
          <title>Identifier (ID)</title>
        </sec>
      </sec>
      <sec id="sec-1-9">
        <title>Equipment 1</title>
        <p>Equipment 2</p>
      </sec>
      <sec id="sec-1-10">
        <title>Equipment 3</title>
      </sec>
      <sec id="sec-1-11">
        <title>Equipment 4</title>
      </sec>
      <sec id="sec-1-12">
        <title>Controller</title>
      </sec>
      <sec id="sec-1-13">
        <title>Database</title>
        <p>
          The questions of the formalized description of the given quality indicators and the integral quality
criterion are considered in [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ] and other works and are not presented here. Features of the construction
of models, methods and criteria applied to the introduction of technological innovation require special
study. This is due to the fundamental uncertainty of innovation processes. Thus, the solution of the
quality assurance problem in this case involves the use models and methods for uncovering
uncertainties.
        </p>
        <p>However, an analysis the uncertainties associated with the risks of quality reduction can be
supplemented by models and methods for analyzing new opportunities. Such opportunities arise when
introducing technological innovations, and their effectiveness can be estimated quantitatively.
3. Functional description and mathematical model of the basic production structure
Technical re-equipment is a key factor for the formation more competitive production. It is aimed at
improving the consumer properties of the produced products, which make up its quality, and also to
increase the technological flexibility of the production process.</p>
        <p>For the phased introduction of technological processes in digital electronics production, it is
necessary to create databases for Solder Paste Inspection (SPI), Automated Optical Inspection (AOI)
and an integrated database of all production processes. To create an intellectual software system, it is
required to write computer programs based on fuzzy logic and allow the machine to make a decision
on its own, which increases the productivity of the manufacturing process for the manufacture of
electronic products. When developing the model of the production process, it is required to perform
the operational detailing of the technological process. Using databases, it is easier to find and select
the necessary production design tools for the phased development of electronic products. The creation
of such software is determined by the insufficient degree of elaboration of the questions of modeling
the production process in the framework of the creation of innovative technological systems
implemented within the framework of the "Industry 4.0" concept.</p>
        <p>The urgency of production of innovative electronics, its miniaturization and import substitution
leads to the need to develop a process production model, as well as new methods for modeling
technological processors to improve their quality.</p>
        <p>
          The mathematical model of processes based on Markov chains was proposed in [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ]. To model the
processes in this paper we use the Kolmogorov equations. On the basis of this model are all the
probabilities of states as a function of time, the volume of the batch produced and the intensity of the
equipment loading. In terms of quality, these probabilities determine the estimates of non-conforming
products when performing individual operations and final marriage. For a detailed presentation of the
production process and subsequent interpretation of operations in a formalized form, modeling is used
in the iThink program.
        </p>
        <p>On the basis of the state graph of the production process are all the probabilities of states as a
function of time. To this end, Kolmogorov's equations are formulated and solved, the differential
equations in which the unknown probabilities are the probabilities of states.</p>
        <p>The production process for the serial production of the electronics batch consists seven steps,
shown in figure 3.
subsequent state Sk+1 the transition probability is the same and is equal to i.</p>
        <p>To determine single-channel final probabilities, the Kolmogorov system of equations is used:
 pn1  nypn  0
 p0  yp1  0

 L

 pk 1 ky pk k 1 ypk 10, k 2, n1

 L</p>
      </sec>
      <sec id="sec-1-14">
        <title>The normalization equation for the system is:</title>
        <p>Solution of the system
n  0 a!</p>
        <p> , pk  p0kk! , k 1,n
where
  </p>
        <p>y
- this is the volume of the produced batch (or this can be the intensity of the loading of equipment)
p f 7  pn  p0 nn!
where pf7 - the probability of inconsistency at the end of the production process (for single-channel
final probabilities).</p>
        <p>According to the formulated equation, the probability of a marriage is equal to the probability pn
Kolmogorov's system of equations for multichannel total probabilities:
(2)
(3)
(4)
(5)
(6)</p>
      </sec>
      <sec id="sec-1-15">
        <title>The normalization equation for the system is:</title>
        <p>nm (8)
 p 1
k0 k</p>
        <p>To solve the equation, it is necessary to introduce an additional coefficient . The coefficient will
be a measure of the load per stage.</p>
        <p>  n  ny (9)</p>
        <p>The solution of the Kolmogorov system of equations is expressed in terms of the probability of
system downtime p .</p>
        <p>0
Probability of marriage is the probability that the system is in a state Snm</p>
        <p>Pfail  pnm  p0 nm nn (12)
n!
- the probability of inconsistency at the end of the production process (for multi-channel final
probabilities).</p>
        <p>Thus, on the basis of modeling, the proposed universal model makes it possible to determine the
probability of the appearance of defective products at the end of the production process and all the
probabilities of states as a function of time.</p>
        <p>For the gradual introduction of technological innovations in the model, it is possible to introduce
the stages and values of parameters for a particular production.</p>
        <p>For definiteness, as an example, consider a model that describes the limiting probabilities of all
states of stages on the basis of a detailed description of the interaction of production process links.</p>
        <p>The model consists of seven elements of the production process, namely:
1. loading operation of circuit boards and components,
2. solder printing operation,
3. solder paste inspection,
4. operation of component placement,
5. oven operation,
6. operation of lasermarking,
7. operation of automatic optical inspection.</p>
        <p>Managed manufacturing process of manufacturing electronics in the package of structural
mathematical modeling is presented in figure 4.</p>
        <p>Consider the ordered set of states of production of electronics S1, S2, S3, S4, S5, S6, S7.</p>
        <p>Transitions can only be carried out sequentially, i.e. from the state 1 and 2 and vice versa in the
event of a marriage. All transient flows translate the production process along the arrows with the
corresponding intensities: ak,k+1 or ak+1,k.</p>
        <p>In accordance with the model constructed in iThink, algebraic equations for limiting probabilities
of states of the production process are compiled and solved (the equations are made up of the
possibility of transition from each previous state to the next).</p>
        <p>When solving Kolmogorov's differential equations, the probabilities of states are:</p>
        <p>For S1 12 p1 21 p2 (13)
 56 p5  65 p6

 67 p6  76 p7

 76 p7  67 p6
The normalization equation for the system has the form:
p  p  p  p  p  p  p 1
1 2 3 4 5 6 7
(25)
(26)</p>
        <p>When analyzing the yield of suitable products, the state of the production stage is Sk , transition of
the system from the previous state Sk in the following has the form Sk 1 , transition Sk into a state of
inappropriate production is Sk1 .</p>
        <p>The solution of the system of equations has the form:</p>
        <p>
          Thus, the obtained values of the probabilities are refined in comparison with the general model,
since they take into account the features of the interaction of the links representing the stages of
production.
4. Mathematical model of production with introduction of technological innovations
As the initial model, we will examine the stages of the production process, using the control effect, the
human factor presented in Figure 4. The model is a further development (figure 3) and differs by the
justified introduction of direct and the elimination of unrealized feedbacks for the subsequent
introduction of technological innovations. For certainty, the operations (CA3, CA7) performed by a
person are presented. This state corresponds to the standard [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ].
(27)
(28)
(29)
(30)
(31)
(32)
(33)
        </p>
        <p>The introduction of technological innovations is carried out by replacing successive
interoperational links with the enlarged operators presented by CA3, CA7. During the implementation
of CA3, CA7 replaced with M2M and M2M SPI-OAI (figure 5). These operators correspond to the
basic structure (figure 2).</p>
        <p>The management of the production process is replaced by an intelligent control system. The
intellectual system is a fuzzy controller with the ability to introduce or exclude the necessary
conditions for the operation of the production process.</p>
        <p>The operation of the systems is the inter-machine interaction.</p>
        <p>The intellectual self-learning system is implemented in two stages:
 checking the solder paste,
 automatic optical inspection operation.</p>
        <p>One of the elements of assessing the quality of products at the stage "testing solder paste" can be:
 coating the area with solder paste;
 filling the volume of the stencil;
 compliance with the shape of the hole;
 the presence of jumpers.</p>
        <p>In the event that one of the indicators deviates from the predetermined satisfying limits, the system
transfers the mounted PCB to the nonconformity state and independently decides on taking corrective
actions to eliminate the nonconformity.</p>
        <p>Creation of a detailed process model of the manufacturing process (figure 5) of the electronics
manufacture, which has an open architecture that allows it to expand to solve new problems and use a
single intellectual, self-learning information support built on the basis of the fuzzy logic apparatus,
forming the "knowledge base" of the enterprise in which the all results and knowledge obtained as a
result of the enterprise's activities will reduce the possible production risks associated with human
skim factor and reduce the number of defective products.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>5. Conclusion</title>
      <p>The new models proposed in the article provide a description of the simple structures of the production
process and the transition to technological innovations introduced in these systems. Innovations M2M
and M2M SPI-OAI are elements of the concept "Industry 4.0", allowing to reduce the possible
production risks associated with the human factor and reduce the amount of defective products. When
developing models, the mathematical apparatus of the Kolmogorov equations was used to determine
the limiting probabilities as a function of time and the means of structural mathematical modeling
iThink.</p>
      <p>
        These models allow to estimate the proportion of nonconforming products and final marriage and
to provide ever higher quality in the implementation of technological innovations. The accumulation
of experimental data in databases and the subsequent creation of a knowledge base creates the
conditions for uncovering uncertainties, assessing risks and opportunities identified [
        <xref ref-type="bibr" rid="ref10 ref11 ref6 ref7 ref8 ref9">6 -11</xref>
        ]. For this it
is supposed to use soft calculations and fuzzy logics in the ontological knowledge base with a frame
structure. Compliance with quality requirements is initially described in fuzzy categories using
piecewise linear membership functions in the tolerance field, the type of which is specified in the
learning process. Integration of information from elements of digital production and operational
knowledge in the knowledge base will ensure the quality of electronics products and minimize the
human factor.
      </p>
    </sec>
  </body>
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