SU1433707A1 - Paste for soldering mounted radio components of radioelectronic equipment - Google Patents

Abstract

The invention relates to pas; ike, in particular, to the composition of a paste for soldering mounted elements of electronic equipment, and can be used in electronics and instrument making both in the manufacture of electronic products and in their installation in equipment. The goal is to increase the percentage of yield of elements during installation, the quality and reliability of contact assemblies and products by lowering the reflow temperature and increasing the plasticity of the tinned layer. The paste contains indium-cadmium solder powder as a solder powder, and dipentene tetrabromide as an additional active component of the flux in the following ratio of components, wt%: indium 34-53; cadmium 35-50; rosin 0.7-1.0; tri-ethanolamine 10.7-14.2; tetrabromide dipentene 0.6-0.8. The paste has a lower melting point and when installing the C 2-12 thread resistors, it allows to increase the yield by 40% and the stability of the contact during operation by 5-10 times. 1 tab. with to

Description

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The invention relates to soldering, to the composition of the paste for soldering-mounted elements of electronic equipment, and can be used in electronics and instrument making both in the manufacture of electronic products (IET) and in their installation into equipment.

The solder paste is a mixture of powdered solder and organic binder, which includes the flux. Solder pastes can be applied to the treated surface by screen printing or using special dispensing devices. Then, parts covered with a solder paste, which has a glue-up, with its ability, are mounted with hinged elements, after which the paste is melted.

The purpose of the invention is to increase the percentage of yield of elements during installation, quality and reliability of contact assemblies and products by lowering the reflow temperature and increasing the plasticity of the tinned layer.

The paste contains components in the following ratio, wt.%: Indium34-53

Cadmium 35-50

Rosin 0.7-1.0

Triethanolamine 10.7-14.2

Tetrabromide

dipentene 0.6-0.8.

The choice of indium-cadmium solder powder is determined by the goal of achieving high plasticity of the melted paste, which is especially necessary for attaching parts to surfaces with different CTE. and with a low adhesive strength of contacts mounted mounted-elements. : The ratio of indium to cadmium in a paste provides a melting point of the paste, which does not affect the characteristics of the soldered products, and at the same time allows the products to be operated at maximum operating temperatures (125 ° C).

The development of plasticity, the relatively low reflow temperature and the correspondingly high reliability of the solder joints are a consequence of the combination of the indium and cadmium ratios with a neutral activator, tetrabro-MIDOM dipentene, in the composition of the paste for soldering.

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five

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five

0

five

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five

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five

the amount of rosin in the solution of triethanolamine.

The reliability of paired connections is assessed by the most critical example — the relative change in the resistance value of resistors C2-12 after prolonged (56 days) exposure to high humidity (93 ± 5%, 40 ° C). This type of testing allows one to evaluate both the strength properties of the formed steam unit and the susceptibility to corrosion associated with the aggressiveness of the flux that forms part of the paste.

When installing resistors with the help of a prototype paste, the values of / R / R reach 6j5%, while when mounted with a paste of the proposed composition, these changes do not exceed 0.9%.

Indium-cadmium solder is produced by fusing indium and cadmium in a porcelain crucible taken in the required ratio. In order to prevent oxidation, the soldering of the components is performed under a layer of charcoal. First, the more fusible component, indium, is melted, then cad is introduced into the melt.

Indium-cadmium solder powder is obtained by dissolving molten solder at a pressure of 2-3 atm in inert gas. The dispersion of the powder is in the range of 2- 60 µm.

The paste is prepared as follows.

First, rosin is dissolved in tri- (ethanolamine at 60-80 ° C), then tetrabromide dipentene is added at a temperature of 40-50 seconds with stirring, after which the solder powder is added, ensuring uniform paste.

Examples of the paste with the main characteristics: the melting temperature, the plasticity of the layer, the percentage of yield of the products (assemblies B19 with resistors C2-12) and the average value of the change in resistance after the legs legs and moisture are shown in the R table.

As follows from the data of: g, in the table, the positiv7 and 1 e ||) effect - an increase in plasticity, a decrease in the melting temperature of the plastics and the provision of high reliability of the solder joint - is achieved from within the limits specified: g: о ci .uMieiiHKi with a prototype hardness of a slo.

reduced from 22 to 10 kg / mm, the reflow temperature - from 280 to. The percentage of usable products output by the example of mounting resistors C2-12 is 2 times. At the same time, the stability of the parameters of elements under climatic influences is also significantly increased.

Accordingly, outside the specified intervals, the goal is not reached. For example, when the minimum value is reached (indium content 30%) with a slight decrease in the reflow temperature, the service quality becomes unsatisfactory, respectively, the percentage of usable products is at the level of the prototype.

When the In content is exceeded (60%, the melting temperature becomes comparable to the operating temperature, which is unacceptable. In addition, the high content of indium-cadmium solder powder (92%) leads to a sharp deterioration in the printing properties of the paste, as a result of which the samples with resistors could not be manufactured and tested.

The introduction of tetrabromide dipentene into the paste in the specified interval ensures the achievement of high quality service and high stability of products under operating conditions, including at high humidity.

Thus, the proposed paste has a lower melting point and hardness of the layer, which, when mounting a number of elements (

For example, the thread resistors C2-12) allows to increase the yield by 40% and the stability of the contact with eq, 4R

sploation (decreases 5-10 times) to

The composition, due to the reduced rosin content and the use of more neutral activators in the composition of the flux, provides for better washing of the flux after the paste melts, which, in turn, has a positive effect on the quality and reliability of the products.

Formula of invention

Solder paste for mounted electronic equipment, containing fine powdered solder, triethanolamine and rosin, characterized in that, in order to increase the percentage of yield of components during installation, the quality and reliability of contact nodes and products by lowering the reflow temperature and increasing the ductility of the tinned layer, the paste additionally contains dipentene tetrabromide, and as a solder, indium cadmium solder in the following ratio of components, wt.%:

Indium

Cadmium

Rosin

Tetraethanolamine

Tetrabromide

dipentene

34-53

35-50

0.7-1.0

10.7-14.2 0.6-0.8

4353ЗA, О

433550.0

----

-, -

0,80,71,0

12,510,714,2

60

thirty

32

50

2, 17.0

52

33

2.0

1.0

10.0

0.7

185

ten

83

0.6

160

85

0.2

0.15,

h: 0.05-0.4 0, G5-0.9

,

Printing properties Choir Chorus

Visual assessment of the quality of the laid layer Ex.

Ex.

0.8

0.5

1.0

135

230

18

0.5 0.5

280 22

81

40

45

-.

.

0.3-4.2

3jl, 0.5-6.5

Not Chorus. satisfied

Pleased

Ex.

Not pleased

satisfied

Choir,

Claims (1)

Claim Paste for soldering mounted components of electronic equipment, containing fine powder solder, triethanolamine and rosin, characterized in that, in order to increase the percentage of suitable elements during installation, the quality and reliability of contact nodes and products by reducing the melting temperature and increasing the plasticity of the tinned layer, paste additionally contains dipentene tetrabromide, and indium as cadmium solder as a solder in the following ratio of components, wt.%: Indium 34-53 Cadmium 35-50 Rosin 0.7-1.0 Tetraethanol amine 10.7-14.2 Tetrabromide dipentene 0.6-0.8 The content of components, wt.% ₅ and characteristics Example I Example 2 Example 3 Beyond values Prototype one 2 3 four £ Indium 43 53 34.0 60 ^thirty - Cadmium 43 35 50,0 32 fifty - Tin - - - - - 52 Lead - - - - - ³³ Silver - - - - - 2.0 Rosin 0.8 0.7 1,0 0.5 2.0 1,0 Triethanolamine 12.5 10.7 14.2 7.0 17.0 10.0 eleven Food sales ............... 7 .......! tables ί one 9 3 π <· ¹ Carboxylic acid - - - - - 1,0 Dipentene tetrabromide 0.7 0.6 0.8 0.5 1,0 - Cyclohex— zero *** Pine oil lo - - - - - 0.5 Reflow Temperature Op. paste, C 185 160 210 135 230 280 Microhardness of the tinning layer, kg / mm ² 10 9 12 8 eighteen 22 The output of suitable B19 blocks with resistors C2-12 after mounting with solder paste 83 85 81 40 45 The relative change in the value of resistance after tests for moisture resistance -, / " 0.2 0.1-0.6 0.15 0.05-0.4 0.25 0.15-0.9 B0 0.3-4.2 3.5._ _ 0.5-6.5 Printed Properties Choir Chorus. Choir Not satisfied Choir Satisfied Visual assessment of the quality of the tinned layer Ex Ex. Satisfied Not satisfied Choir