JPH0558278B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a printed wiring board.

[Conventional technology]

In general, printed wiring boards are made by forming the required circuit pattern on an insulating substrate via a conductor.
It is constructed by incorporating required electronic components into this circuit pattern.

In order to assemble the electronic components onto the printed wiring board, the circuit pattern surface of the printed wiring board is immersed in a molten solder tank or jet solder tank while the electronic components are mounted on the printed wiring board. This is accomplished by attaching solder to the leads of the electronic component and the circuit pattern to electrically and mechanically connect them.

Furthermore, when soldering the circuit pattern and the lead of the electronic component, for example, a solder resist is applied to the entire surface of the circuit pattern except for the land portion to be soldered so that the solder adheres only to the connected parts of the two. However, as circuit patterns become smaller, the distance between adjacent circuits becomes narrower, and the distance between connecting lands with leads of electronic components also becomes narrower, which impairs the original function of the solder resist. There have been cases where a bridging phenomenon occurs between lands due to the soldering, and correction work is required.

Therefore, in order to prevent such solder bridging,
In order to prevent solder bridging, especially in areas where the land spacing is narrow, when manufacturing the printed wiring board, a conductor pattern is printed on the insulating substrate, and lands to be soldered are left on the surface on which the conductor pattern is formed. to form a first layer of soldering resistance layer on the entire surface,
In addition, a method is adopted in which a soldering resistance layer for preventing solder bridging is formed on the first layer soldering resistance layer to prevent solder bridging at least in areas where the land spacing is narrow. It has even been disclosed in Publication No. 54-41162.

[Problem that the invention seeks to solve]

However, the method of forming the first layer of soldering resistance layer and then forming a soldering resistance layer for preventing bridging on the first layer of soldering resistance layer is a method in which the soldering resistance layer of the first layer is Since the resistive layer is formed on the entire surface of the conductor pattern, leaving a land to be soldered, high alignment precision is required to leave the land to be soldered, and the solder of this first layer is required to be highly accurate. After the formation of the soldering resistive layer, a soldering resistive layer for bridging prevention is formed on the first layer of soldering resistive layer, so in addition to the alignment accuracy for leaving the land to be soldered, This method has drawbacks such as smearing of solder resist ink caused by screen printing when forming a soldering resistance layer on a land portion to be soldered.

Therefore, the present invention has been made in view of the above-mentioned drawbacks of the conventional solder resist, and enables implementation with rough matching accuracy compared to the matching accuracy when implementing the conventional solder resist, and prevents bleeding on the land portion. It is an object of the present invention to provide a method for manufacturing a printed wiring board that can implement a solder resist without any cracks and further improve the quality of a solder hunk in soldering between a land and a lead of an electronic component.

[Means for solving problems]

The method for manufacturing a printed wiring board of the present invention includes the steps of forming a conductive circuit pattern on an insulating substrate, applying a solder resist surrounding a land to be soldered in the circuit pattern, and applying a solder resist to the land and a resist surrounding the land. solder on the entire surface of the circuit pattern, leaving a portion with a diameter larger than the diameter of the land to be soldered and smaller than the outer diameter of the solder resist portion surrounding the land; This process consists of a step of applying a resist.

[Effect]

The present invention applies a solder resist that surrounds a land to be soldered on a circuit pattern surface, and then applies a solder resist to the entire surface of the circuit pattern, thereby reducing difficulty in alignment accuracy and improving workability. It is possible to apply an accurate solder resist without relying on high alignment accuracy, prevent the solder resist from bleeding to the land portion, and increase the height of the solder resist by applying the solder resist that surrounds the land to be soldered. , it is possible to eliminate variations in soldered parts and improve quality stability.

〔Example〕

Embodiments of the method for manufacturing a printed wiring board of the present invention will be described below with reference to the drawings.

(First Example) FIG. 1 is a partial plan view of a printed wiring board showing a first example of the method for manufacturing a printed wiring board of the present invention.

In the drawings, reference numeral 1 denotes an insulating substrate, on one side of which a circuit pattern 2 made of a conductor is formed.

The circuit pattern 2 can be formed by etching the copper foil of a copper-clad laminate or by other conventionally known methods.

Thereafter, a solder resist 6 is applied to surround each land 4 to which the lead of an electronic component provided at the end of each circuit 3 of the circuit pattern 2 is connected.

This solder resist 6 is applied by screen printing using ordinary solder resist ink, and has an inner diameter and width that are the same as the outer diameter of each land 4 or slightly larger than the outer diameter as shown in FIG.
This is carried out by forming an annular solder resist 6 of about 0.5 mm.

Therefore, between each land 4 and each annular solder resist 6, a gap 7 is formed between the inner and outer spans.

In addition, each land 4 and each annular solder resist 6
In the annular solder resists 6 of adjacent lands 4, the overlapping portions 6a are formed by the same annular portions.

Further, after forming the solder resist 6 surrounding each land 4, a solder resist 8 is applied to the entire surface of the circuit pattern 2, leaving each land 4, thereby manufacturing the printed wiring board 10.

The solder resist 8 applied to the entire surface of the circuit pattern 2 has a diameter larger than the outer diameter of each land 4 in each land 4 portion, and leaves a portion with a smaller diameter than the outer diameter of each annular solder resist 6. It is something that is given.

Therefore, according to such an embodiment, circuit pattern 2
The annular solder resist 6 is applied before the solder resist 8 is applied to the entire surface of the circuit pattern 2, and the annular solder resist 6 in the circuit pattern 2 only needs to be aligned in that part. The alignment work can be simplified, and the annular solder resist 6 on each land 4 can be formed without variation due to the simplification of the alignment work.

Furthermore, as shown in the figure, by providing a gap 7 between the outer diameter of the land 4 and the inner diameter of the annular solder resist 6, each of the above-mentioned effects can be further improved.

In addition, when an electronic component lead (not shown) is inserted into the electronic component lead insertion hole 9 of each land 4 and soldered, the annular solder resist 6 surrounding each land 4 As the solder height increases due to the upward movement, each land 4
It is possible to prevent solder bridging between the two.

Furthermore, after the formation of each annular solder resist 6 on each land 4, when forming the entire surface solder resist 8 except for each land 4, in particular, the difference between each land 4 and each annular solder resist 6 is In this regard, each land 4 in screen printing when applying the solder resist 8 is applied leaving a portion larger in diameter than the outer diameter of each land 4 and smaller in diameter than the outer diameter of each annular solder resist 6. This further simplifies the task of aligning with
In addition to making the work on the solder resist 8 itself easier and more accurate, it is also possible to prevent the solder resist ink from bleeding onto each land 4 portion.

(Second Embodiment) FIG. 2 is a partial plan view of a printed wiring board showing a second embodiment of the method for manufacturing a printed wiring board of the present invention.

In the case of such an embodiment, the method of forming the solder resist 6 on each land 4 is different from that of the first embodiment.

That is, in the first embodiment, the solder resist surrounding each land 4 is an annular solder resist 6.
However, in the case of such an embodiment, a hole 60 having a diameter slightly larger than the outer diameter of each land 4 was formed.
This is done by applying a solder resist 60 having a rectangular outer diameter and surrounding each land 4, leaving the area a.

Therefore, other methods are the same as those in the first embodiment, and the same components in the figures are designated by the same numbers and their explanations will be omitted.

Note that the outer shape of the solder resist 60 is not limited to a rectangle, and may be implemented in various shapes according to the design.

Further, the same effects as in the first embodiment can be obtained in this second embodiment.

Furthermore, in the first and second embodiments, an embodiment for each land 4 of a portion was described;
Needless to say, solder resists 6 and 60 are applied to all the lands to be soldered in the circuit pattern 2.

〔Effect of the invention〕

According to the present invention, the solder resist for the land to be soldered in the circuit pattern can be easily and
It has the effect of being able to apply the solder resist accurately, simplifying the alignment work of applying the solder resist to the entire surface leaving the lands to be soldered, and preventing bleeding on the land portions at that time.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view of a printed wiring board showing a first embodiment of the method for manufacturing a printed wiring board of the present invention, and FIG. 2 is a partial plan view of a printed wiring board showing a second embodiment of the same. be. 1...Insulating board, 2...Circuit pattern, 3...
Circuit, 4... Land, 6, 8, 60... Solder resist, 7... Gap, 9... Insertion hole, 10...
printed wiring board.

Claims (1)

[Claims] 1. A step of forming a conductor circuit pattern on an insulating substrate, and a step of applying a solder resist surrounding the lands to be soldered in the circuit pattern while forming a gap between each of the lands and the resist surrounding the lands. , a step of applying a solder resist to the entire surface of the circuit pattern, leaving a portion having a diameter larger than the diameter of the land to be soldered and smaller in diameter than the outer diameter of the solder resist portion surrounding the land. manufacturing method.